Bulletin of the ,, British Museum (Natural History) LIBRARY , Zoology series Vol 44 1983 British Museum (Natural History) London 1983 Dates of publication of the parts No 1 27 January 1983 No 2 24 February 1983 No 3 31 March 1983 No 4 28 April 1983 No 5 26 May 1983 No 6 30 June 1983 ISSN 0007-1 498 Printed in Great Britain by Henry Ling Ltd, at the Dorset Press, Dorchester, Dorset Contents Zoology Volume 44 Page No 1 Observations on the systematics of the genus Difflugia in Britain (Rhizopoda, Protozoa). By Colin G. Ogden 1 No 2 Miscellanea Cirolana cranchi Leach, 1818 (Crustacea: Isopoda: Cirolanidae) redescribed, with notes on its distribution. By N. L. Bruce & Joan Ellis 75 Valettieta, a new genus of deep-sea amphipod (Gammaridae: Lysia- nassidae) with descriptions of two new species from the North Atlantic Ocean. By Roger J. Lincoln & Michael H. Thurston . . . .85 Three new genera of misophrioid copepods from the near-bottom plankton community in the North Atlantic Ocean. By G. A. Boxshall 103 Larval development of British prawns and shrimps (Crustacea: Decapoda: Natantia) 4. Palaemon (Palaemon) serratus (Pennant, 1777) and functional morphology of swimming. By A. A. Fincham . T ...... 125 The larval development of the Angular Crab, Goneplax rhomboides (Linnaeus) (Decapoda: Brachyura). By R. W. Ingle & P. F. Clark 163 The larval and first crab stages of three Inachus species (Crustacea: Decapoda: Majidae); a morphological and statistical analysis. By Paul F. Clark 179 No 3 A review of the Euplotidae (Hypotrichida, Ciliophora). By Colin R. Curds & Irene C. H. Wu 191 No 4 The Opthalmotilapia assemblage of cichlid fishes reconsidered. By Peter Humphry Greenwood . . . . . 249 No 5 Osteology, genitalia and relationships of the Acanthodactylus (Rep- tilia: Lacertidae). By E. N. Arnold 29 1 No 6 Morphological studies on some Difflugiidae from Yugoslavia (Rhi- zopoda, Protozoa). By Colin G. Ogden & Andjelija Zivkovic . 341 Bulletin of the British Museum (Natural History) Observations on the systematics of the genus Difflugia in Britain (Rhizopoda, Protozoa) Colin G. Ogden Zoology series Vol 44 No 1 27 January 1983 The Bulletin of the British Museum (Natural History), instituted in 1949, is issued in four scientific series, Botany, Entomology, Geology (incorporating Mineralogy) and Zoology, and an Historical series. Papers in the Bulletin are primarily the results of research carried out on the unique and ever-growing collections of the Museum, both by the scientific staff of the Museum and by specialists from elsewhere who make use of the Museum's resources. Many of the papers are works of reference that will remain indispensable for years to come. Parts are published at irregular intervals as they become ready, each is complete in itself, available separately, and individually priced. Volumes contain about 300 pages and several volumes may appear within a calendar year. Subscriptions may be placed for one or more of the series on either an Annual or Per Volume basis. Prices vary according to the contents of the individual parts. Orders and enquiries should be sent to: Publications Sales, British Museum (Natural History), Cromwell Road, London SW7 5BD, England. World List abbreviation: Bull. Br. Mus. nat. Hist. (Zool.) Trustees of the British Museum (Natural History), 1983 The Zoology Series is edited in the Museum's Department of Zoology Keeper of Zoology : Dr J. G. Sheals Editor of Bulletin : Dr C. R. Curds Assistant Editor: Mr C. G. Ogden ISSN 0007- 1 498 Zoology series Vol 44 No 1 pp 1-73 British Museum (Natural History) Cromwell Road London SW7 5BD Issued 27 January 1983 Observations on the systematics of the genus Difflugia in Britain (Rhizopoda, Protozoa). F GENERAL 28 JANW83 ^4L Colin G. Ogden Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD Contents Synopsis Introduction Materials and methods Systematic descriptions Pyriform and elongate species . . . . Pointed species or those with protruberances . Ovoid or spherical species Compressed species Discussion References Index . 1 1 2 2 2 27 45 59 66 69 73 Synopsis Detailed descriptions of the shell structure in thirty-eight species of Difflugia are given, and further information on one species which has been redescribed in an earlier report (Ogden & Fairman, 1979) is included. Two new species, Difflugia hiraethogii and D. stoutii, are described, and other systematic changes include the following new combinations: D. cylindrus (Thomas, 1953), D. lacustris (Penard, 1899), D. microclaviformis (Kourov, 1925), D. microstoma (Thomas, 1954), D. parva (Thomas, 1954), D. tennis (Penard, 1890), D. tricornis (Jung, 1936), D. venusta (Penard, 1902) and D. distenda nom, nov., D. gassowskii nom, nov., D. paulii nom. nov., D. rotunda nom. nov. Seventeen of these redescriptions are new records for the British Isles. The structure of the shell is discussed and the patterning of the organic cement which binds the particles together is shown to be a useful taxonomic character. Introduction The taxonomy of specimens belonging to the genus Difflugia is based mainly on differences in size and shape of the agglutinated shells constructed by these animals. Comparison of cytoplasmic features are either difficult or impossible because most of it is encased by the shell which is often opaque. Differences in the shell features have resulted in about three hundred named species, varieties and forms being currently attributed to the genus. This proliferation of species is due to a combination of the lack of good diagnostic features and inadequate descriptions. The problem is clearly shown in the only comprehensive survey of the genus, based on African specimens, by Gauthier- Lievre and Thomas (1958). In this work the authors had difficulties with several groups of individuals which shared common features, and as a result, about half of the 129 species described were designated as varieties or forms. Some earlier studies (Ogden, 1979, 1980; Ogden & Fairman, 1979) were con- cerned with the variation of specimens having a pyriform shell, and the surface Bull. Br. Mus. nat. Hist. (Zool.)44 (1): 1-73 Issued 2 7 January 1983 2 C. G. OGDEN ultrastructure as revealed by the scanning electron microscope. The results showed that there was usually a limited variation in size, shape and composition of the shell within a species, whilst in some instances the patterning of the organic cement which binds the particles together was a reliable specific character. The present account uses the experience gained from these previous studies to extend the examination of shell structure in Difflugia, and to establish specific features for ten of the varieties of Difflugia oblonga listed by Gauthier-Lievre and Thomas (1958). Thirty nine species are described, of which some are new records for the British Isles. Some 600 specimens have been examined and over 3000 micrographs representing different aspects of the shells are retained in the Protozoa Section, Department of Zoology as part of the study collection. Materials and methods Samples have been collected from several localities in England and Wales during the last four years. The material gathered varied from mosses, water plants including the substrate associated with the roots, and clumps of algae. Type of habitat ranged from areas of bog, banks of streams and small ponds in the New Forest, Lake District and North Wales to the dykes and rivers of Norfolk and Suffolk. Information relating to locality, date and type of sample is given with the description of each species as several have been found in more than one habitat. Specimens of Difflugia were selected by searching through small isolates of material in a petri dish. Specimens were extracted using a glass micropipette, washed in several transfers through distilled water, and then individual shells were manipulated with a single-hairbrush onto a small drop of Araldite on a previously cleaned cover slip. When about twenty specimens were positioned on each cover slip it was glued with Araldite onto a standard aluminium stub. In a few instances the very small delicate specimens collapsed before or during manipulation, this problem was overcome by transferring the washed specimens in a small drop of water onto cleaned cover slips and allowing it to dry. Prepared stubs were coated evenly with gold or gold/palladium, using a conventional sputter coating device, and examined in a Cambridge Stereoscan SI 80 operating at lOkV. The results were recorded on Ilford HP5 film. Systematic descriptions In a previous review (Gauthier-Lievre & Thomas, 1958) of the genus the species were divided into ten groups, namely; lobed, collared, compressed, urceolate, globose, ovoid- globose, elongate, acute angled, horned and pyriform, but no particular significance was attached to these groupings. However, it does show the diversity of shell shape that has been included in the genus. Similarly in this report the species have been grouped together, the pyriform and elongate species are described first, followed by those which are pointed or have aboral protruberances, then the ovoid or spherical and finally the two compressed species. Pyriform and elongate species Difflugia bryophila (Penard, 1 902) Jung, 1 942 Difflugia pyriformis var. bryophila Penard, 1 902 Difflugia oblonga var. bryophila (Penard, 1902) Gauthier-Lievre & Thomas, 1958 DESCRIPTION. The shell is brown, pyriform, with the sides usually tapering evenly to the aperture (Figs, la & d), although the occasional specimen may be slightly mis-aligned or DIFFLUGIA IN BRITAIN Fig. 1 Difflugia bryophila: a, lateral view of shell with large particles obscuring the basic outline x780; b, apertural view x760; c, portion of shell surface showing the distribution of organic cement (arrowed) x 5100; d, lateral view of specimen with typical basic outline x440; e, detail of organic cement x 24 000. 4 C. G. OGDEN Table 1 Range of measurements (in um) of pyriform specimens. Number of specimens Species Length (L) Breadth (B) Diameter of aperture (d) B/L d/L 3 D. minutissima 7-14 6-10 2-3 11 D. pulex 28-43 21-30 7-10 0-78 + 0-10 0-26 ±0-04 19 D. pristis 33-42 21-31 10-13 0-6910-08 0-3110-03 3 D. glans 67-74 44-50 19-22 36 D. manicata 60-88 37-54 12-20 0-61+0-04 0-20 + 0-02 25 D. tenuis 60-87 37-50 17-27 0-57 + 0-06 0-30 + 0-03 7 D. linearis 96-108 32-38 12-13 0-35 + 0-02 0-12 + 0-01 21 D. gassowskii 91-120 45-55 16-21 0-50 + 0-05 0-18 + 0-02 39 D. bryophila 83-141 49-67 16-22 0-55 + 0-07 0-17 + 0-02 36 D. petricola 96-124 61-84 20-31 0-65 + 0-06 0-23 + 0-03 *(47) (D. petricola) (108-151) (72-99) (25-36) (0-62+0-05) (0-22 + 0-02) 4 D. paulii 119-130 48-54 19-23 0-40 ±0-01 0-17 + 0-01 38 D. lanceolata 108-155 56-92 22-32 0-51 ±0-05 0-20 + 0-02 6 D. parva 131-162 61-80 19-27 0-51+0-Q4 0-17 + 0-02 23 D. lacustris 140-231 63-94 26-42 0-41+0-04 0-18 + 0-02 22 D. cylindrus 186-264 91-130 34-49 0-53 + 0-05 0-21+0-02 46 D. viscidula 165-284 116-215 46-89 0-75 + 0-09 0-3010-04 *measurements quoted from an earlier report (Ogden & Fairman, 1979) have a large particle obscuring the even-tapering (Fig. la). It is composed mainly of a mixture of small to medium pieces of quartz and the occasional diatom frustule or siliceous flagellate cyst. In common with most rough, thick shells, organic cement is seen infrequently (Fig. Ic), it appears as an open network, with a mesh about 350-450 nm in diameter. The walls of the mesh are not pronounced but blend with the matrix, the mesh openings are often covered by inner strands of cement which appear to form a smaller mesh (Fig. le). The aperture is circular and surrounded by small particles (Fig. Ib), in several of the specimens examined small flagellate cysts had also been incorporated to give an irregular margin. MEASUREMENTS (in um). See Tables 1 and 2. MATERIAL EXAMINED Specimens were collected from samples of Sphagnum moss gathered at Mately Bog, Lyndhurst, New Forest, Hampshire in March, 1980 and at Mynnd Hiraethog, Denbigh, Clwyd, North Wales in August, 1980. GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Belgium (Chardez & Gaspar, 1976; Couteaux, 1969), British Isles (Cash el al, 1919), Chile (Jung, 1942), Congo (Chardez, 1964), Czechoslovakia (Rosa, 1957), France (Thomas, 1954), Gambia (Decloitre, 1947), Germany (Jung, 1936), Roumania (Godeanu et al., 1973), Russia (Kourov, 1925), Spain (Gracia, \912a), Switzerland (Penard, 1902), Tunisia (Gauthier- Lievre & Thomas, 1958), West Africa (Decloitre, 1948). REMARKS. This description is in good agreement with Penard (1902) who stated that the sides were rather straight and that it was formed of stones which were usually large and angular. Amongst the sample from Matley Bog were specimens of Pontigulasia which were indistinguishable in size and shape from those of D. bryophila. Observations of the former specimens by optical microscopy to determine the presence of an inner diaphragm, the distinguishing generic character for Pontigulasia, are often difficult. However, detailed examination by scanning electron microscopy showed that, unless the apertural opening is blocked, it was easy to identify the inner diaphragm and that additionally there are differ- ences in their organic cement patterns (a review of the genus Pontigulasia is in preparation). DIFFLUGIA IN BRITAIN 5 The random selection of these specimens from the sample gave a ratio of 3 : 1 in favour of D. bryophila. Difflugia cylindrus (Thomas, 1953) comb. nov. Difflugia oblonga var. cylindrus Thomas, 1953 DESCRIPTION. The shell is usually opaque, cylindrical, tapering evenly from the aboral region to the aperture (Fig. 2a). It is composed mainly of medium to large pieces of quartz with the occasional diatom frustule on the rough surface, but the latter are seldom incorporated into the thick structure. Small areas of organic cement in the form of a network are seen infrequently (Fig. 2d). Each mesh of the network is between 300-500 nm in diameter, has thick walls and is covered by a thin perforated layer of cement, the pores of which are evenly distributed and are about 30 nm in diameter (Figs. 2e & f)- The aperture is irregular in both outline and composition, being roughly circular and usually surrounded by small particles but often incorporating medium particles that produce a jagged margin (Fig. 2b & c). MEASUREMENTS (in um). See Tables 1 and 2. MATERIAL EXAMINED. Specimens were collected from a sample of aquatic plants taken at the banks of the River Brett, near Hadleigh, Suffolk in August, 1979. GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Austria (Laminger, 19736, 1975, 1976), Belgium (Chardez, 1980; Chardez & Caspar, 1976), Congo (Chardez, 1964), France (Thomas, 1953, 1954; Thomas & Mabille, 1956), Germany (Voeltz-Hohn, 1971), Ivory Coast (Gauthier-Lievre & Thomas, 1958), Morocco (Gauthier-Lievre & Thomas, 1958), Poland (Moraczewski, 1965). REMARKS. This species was initially described by Thomas (1953) as a new variety of D. oblonga, he also listed what he considered to be previous descriptions of this variety under the general descriptions of D. oblonga given by earlier workers. These are not repeated here, but suggest that this variety may be found throughout Europe. The shape, structure and size of the shell, together with the distinct patterning of the organic cement matrix as described above, are considered to be good specific characters sufficient to warrant the raising of this variety to species rank. Difflugia gassowskii nom. nov. Difflugia pyriformis longicollis Gassowsky, 1936 Difflugia longcollis (Gassowsky, 1936) Ogden & Hedley, 1980 DESCRIPTION. The shell is pyriform, with a distinct short neck about one-third of the body length, and a rounded aboral region (Fig. 3a). It is rough and composed of small to medium angular pieces of quartz, small areas of organic cement are sometimes seen between particles (Fig. 3b). The cement is in the form of a network, the mesh of which is about 400-550 nm in diameter and the walls 125-200 nm thick, each mesh enclosure has a covering with small perforations about 50 nm in diameter (Fig. 3c). The aperture is circular. MEASUREMENTS (in um). See Tables 1 and 2. MATERIAL EXAMINED. Specimens were collected from samples of Sphagnum moss gathered at Holmsley Lodge, Burley, New Forest, Hampshire in March, 1980 and at Clocaenog Forest, Denbigh, Clwyd, North Wales in August, 1980. GEOGRAPHICAL DISTRIBUTION. Belgium (Chardez, 1980; Couteaux, 1969), British Isles (Ogden & Hedley, 1980), Germany (Voeltz-Hohn, 1971), Netherlands (Hoogenraad & Groot, 1940a), Nigeria (Gauthier-Lievre & Thomas, 1958), Poland (Moraczewski, 1961, 1965), Roumania (Godeanu et al, 1973), Russia (Gassowsky, 1936), Spain (Gracia, 1972a; Margalef, 1955). C. G. OGDEN Fig. 2 Difflugia cylindrus: a, lateral view x450; b, side view of aperture to illustrate the irregular margin x770; c, apertural view x410; d, shell surface with areas of organic cement (arrowed) x4200; e, typical arrangement of organic cement network x 8700; d, detail of organic cement x 27 000. DIFFLUGIA IN BRITAIN Fig. 3 Difflugia gassowskii: a, lateral view x810; b, shell surface with small areas of organic cement x 7600; c, detail of organic cement network x 24 000. REMARKS. This species has been redescribed recently (Ogden & Hedley, 1980), but is included here on two counts, the added detail of the organic cement and the change of name. The name D. longicollis was used initially by Ehrenberg (1854) to describe specimens which now are not considered to belong to the genus Difflugia, nevertheless, under the Rules of Zoological Nomenclature the name is preoccupied. I am grateful to Dr. E. G. Merinfeld, Dalhousie University, Halifax, Nova Scotia, for drawing my attention to this point. ENTYMOLOGY. This species is named after Dr G. N. Gassowsky who first described it from the Kareliens Lakes. Difflugia glansPenard, 1902 DESCRIPTION. The shell is dark, elongate ovoid, tapering towards the aperture and evenly rounded aborally (Fig. 4a). It is composed mainly of small to medium pieces of quartz, C. G. OGDEN a Fig. 4 Dijjlugia glans: a, lateral view x 1400; b, detail of small unidentified cyst x3000; c, apertural view x 1000; d, portion of shell surface showing the close packing of particles x 3500. packed closely together with only a minimum amount of organic cement visible (Fig. 4d). A small cyst, of unknown origin, is seen adhering to the surface of the illustrated specimen (Fig. 4b), otherwise the outline is usually well denned. The aperture is circular and surrounded by both small and medium particles (Fig. 4c). MEASUREMENTS (in um). See Tables 1 and 2. MATERIAL EXAMINED. Specimens were collected from a sample of water plants taken at the DIFFLUGIA IN BRITAIN 9 banks of the River Brett, near Hadleigh, Suffolk in August, 1979 and a gathering of Sphagnum moss from Mynnd Hiraethog, Clwyd, North Wales in August, 1980. GEOGRAPHICAL DISTRIBUTION. Austria^ (Laminger, 19736), Congo (Chardez, 1964), Czechoslovakia (Rosa & Lhotsky, 1971; StSpanek, 1952), Germany (Jung, 1936; Schonborn, 1962), Italy (Grandori & Grandori, 1934; Rampi, 1950), Russia (Kourov, 1925). REMARKS. This species has not been widely reported, which may be because it falls within the range of three more common species namely, D. penardi, D. manicata and D. rubescens. It differs from these three species in being a distinct ovoid shape, from D. rubescens in being dark and not transparent — although Penard's description of a thin, fragile shell for D. glans does not seem compatible with a dark structure which usually suggests that it is robust and strong — and from D. penardi and D. manicata in aperture size and shape. Difftugia lacustris (Penard, 1 899) comb. nov. Difflugia pyriformis var. lacustris Penard, 1899 Difflugia oblonga var. lacustris Cash & Hopkinson, 1 909 DESCRIPTION. The shell is transparent or hyaline, elongate, cylindrical or slightly pyriform (Figs. 5a & b). It is composed of small to medium pieces of quartz, diatom frustules and small siliceous flagellate cysts blended together to form a thin structure intermediate between smooth and rough. Only small areas of organic cement occur at the junction of the shell components (Fig. 5d). The cement is in the form of thick-walled rings, between 700-800 nm in diameter, perforated with either three or four holes, 120-160 nm in diameter, which gives these units a similar shape to a button (Fig. 5e). The cement may occasionally be seen either as rings with a slight indentation or as a network of joined rings. When organised as a network the walls of individual rings may be fused together but the typical button-like form are usually seen at the edges. The aperture is usually circular and surrounded by small particles so that the margin is smooth (Fig. 5c). MEASUREMENTS (in um). See Tables 1 and 2. MATERIAL EXAMINED. Specimens were collected from three samples in the same locality, aquatic plants at the edge of a pond in Burley, and two gatherings of Sphagnum from opposite banks of a small stream at Holmsley Lodge, Burley, New Forest, Hampshire in March, 1980. GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Argentina (Dioni, 1970; Lena & Zaidenwerg, 1975), Austria (Laminger, 19736 1974, 1975), Belgium (Chardez, 1980; Chardez & Gaspar, 1976; Oye, 1953), British Isles (Cash & Hopkinson, 1909), Congo (Chardez, 1964; Gauthier-Lievre & Thomas, 1958), Czechoslovakia (Stepanek, 1967), France (Thomas, 1954; Thomas & Mabille, 1956), Germany (Jung, 1936; Schonborn, 1962a & b), Guatemala (Laminger, 1973a), Italy (Rampi, 1950), Ivory Coast (Gauthier-Lievre & Thomas, 1958), Mexico (Laminger, 1973a), Morocco (Gauthier-Lievre & Thomas, 1958), Poland (Moraczewski, 1961, 1965), Roumania (Godeanu et al., 1973), Russia (Kourov, 1925), Switzerland (Penard, 1902), United States of America (Laminger etal., 1979;Wailes, 1912). REMARKS. The specimens described here agree well with the original description (Penard, 1899)— shell long, cylindrical, larger in the rear, rarely with a small constriction of the neck— and those given later by Penard (1902) and Cash & Hopkinson (1909). Nevertheless, it would appear that these earlier descriptions were based on groups of similar specimens, hence Penard's reference to a constriction of the neck and the diverse illustrations provided by Cash & Hopkinson. As a result of the latter diagrams, two specimens were tentatively identified as D. lacustris in a previous publication (Ogden, 1980). Additional specimens to 10 C. G. OGDEN Fig. 5 Difflugia lacustris: a, lateral view x 450; b, alternative view of same specimen (a.) to illustrate the uniform shape x280; c, apertural view x500; d, shell surface showing the distribution of organic cement x 5800; e, detail of organic cement network x 24 000. DIFFLUGIA IN BRITAIN 1 1 the two mentioned above have been examined and are clearly seen to differ from D. lacustris, they are now referred to D. linearis (see below). The present account shows that D. lacustris has a well denned shape and a distinctive patterning of organic cement which are considered sufficient to designate this a distinct species. Difflugia lanceolata Penard, 1 890 DESCRIPTION. The shell is yellow or hyaline, lanceolate, tapering from the widest diameter situated about two- thirds of the body-length from the aperture, to give a clean outline that is rounded aborally and evenly angled towards the aperture (Fig. 6a). It is composed of small to medium flattish pieces of quartz and some flat diatom frustules so arranged that the shell is thin and smooth, the surface frequently appearing as though it had been polished, a feature that often permits easy identification. An angular piece of quartz may occasionally protrude from the surface but these are uncommon and limited to one or two in any one shell. As the shell components are usually arranged so that they are in close contact with each other there are no large areas of organic cement, nevertheless, a network of small rings of organic cement may be seen between these particles (Figs. 6d, e, f)- The rings are 240-300 nm in diameter and have a distinct wall about 1 50-200 nm in thickness with a smooth membrane over the mesh. When several rings fuse to form a sheet the thick wall is still usuallv apparent. The aperture is circular and well defined because the rim has a thin covering of organic cement (Figs. 6b & c). Variation appears to be limited to cigar-shaped specimens which have almost parallel sides, one such specimen is illustrated by Ogden & Hedley (1980). MEASUREMENTS (in um). See Tables 1 and 2. MATERIAL EXAMINED The majority of specimens came from a sample of Sphagnum moss collected close to a small stream at Holmsley Lodge, Burley, New Forest, Hampshire, a few came from a similar sample on the opposite bank where they were equally abundant, both samples were taken in March, 1 980. GEOGRAPHICAL DISTRIBUTION. Argentina (Vucetich, \913a, /?), Austria (Laminger, 1972c), Belgium (Chardez, 1961; Oye, 1953), Brazil (Green, 1975), British Isles (Cash & Hopkinson, 1909; Ogden & Hedley, 1980), Canada (Decloitre, 1965), China (Decloitre, 1965), Congo (Chardez, 1964), Czechoslovakia (Opravilova, 1974), France (Thomas, 1954; Thomas & Mabille, 1956), Germany (Schonborn, 1975), Hungary (Gal, 1969), Java (Bartos, 1963a), Morocco (Gauthier-Lievre & Thomas, 1958), Poland (Golemansky, 1970; Moraczewski, 1961, 1965), Roumania (Godeanu et al, 1973), Sudan (Gauthier-Lievre & Thomas, 1958), Switzerland (Penard, 1902), Venezuela (Grospietsch, 1975), West Africa (Decloitre, 1965), United States of America (Decloitre, 1965). REMARKS. The organic rim surrounding the aperture is shared with one other pyriform species of Difflugia, namely D. rubescens where the cement is in the form of tooth-like projections (see PI. 66 in Ogden & Hedley, 1980). The only other species of which we are aware that has an organic rim is D. oviformis, but this was transferred to a new genus Netzelia by Ogden, 1979. D. lanceolata is characterized by its uniform size and outline. Difflugia linearis (Penard, 1 890) Gauthier-Lievre & Thomas, 1958 Difflugia oblonga var. linearis Penard, 1890 Difflugia lacustris in Ogden, 1980 DESCRIPTION. The shell is transparent, flask-shaped or elongate pyriform, having a long thin neck with parallel sides and a slightly swollen, rounded aboral region (Fig. 7 a). The surface is sometimes slightly uneven because of projecting particles, but generally it has a regular 12 C. G. OGDEN Fig. 6 Difflugia lanceolata: a, lateral view x 930; b, apertural view x 760; c, side view of aperture to illustrate the thin covering of organic cement around the rim x 1500; d, shell surface with small isolates of organic cement x4400; c, small rings of organic cement between particles x 7600; f, detail of organic cement x 24 000. DIFFLUGIA IN BRITAIN 13 Fig. 7 Difflugia linearis: a, lateral view x950; b, apertural view x!200; c, portion of shell surface showing areas of organic cement (arrowed) x 14 000; d, detail of organic cement X 24 000. outline. It is composed of a mixture of flattened pieces of quartz, small whole, flat diatom frustules, fragments of flattish frustules, small siliceous shell plates and round flagellate cysts. Small areas of organic cement, in the form of a network with an open mesh, are occasionally seen (Fig. 7c), The open mesh has a diameter of about 300 nm and walls 100 nm thick (Fig. 7d). In appearance, the openings of the mesh suggest that it may have been covered at some time and has subsequently been broken, but only the examination of further specimens will establish its normal condition. The aperture is circular and usually surrounded by small particles (Fig. 7b). MEASUREMENTS (in um). See Tables 1 and 2. MATERIAL EXAMINED. Specimens were collected from Sphagnum moss gathered at Holmsley 14 C. G. OGDEN Lodge, Burley, New Forest, Hampshire on two occasions, May, 1978 and March, 1980, and at Myndd Hiraethog, Denbigh, Clwyd, North Wales in August, 1980. GEOGRAPHICAL DISTRIBUTION. Austria (Laminger, 19736, 1975), Belgium (Chardez, 19616), British Isles (Ogden, 1980), Bulgaria (Golemansky, 1967), Congo (Chardez, 1964), France (Thomas, 1954), Germany (Penard, 1890), Ivory Coast (Gauthier-Lievre & Thomas, 1958), Nepal (Laminger, 19726), Roumania (Godeanu et at, 1973). REMARKS. The initial description of this species (Penard, 1890) was brief, and relies mainly on the diagrams. The scarcity of subsequent reports may be due to this inadequate description or the difficulty in finding this species, which by being thin, long and transparent Fig. 8 Difflugia manicata: a, lateral view x 1300; b, apertural view x 1 100; c, and d, detail of organic cement with the ill-defined inner structure (arrowed) x 30 000. DIFFLUGIA IN BRITAIN 15 Fig. 9 Difflugia minutissima: a, lateral view to show the arrangement of flattish particles x 6700; b, detail of aperture x 10 000; c, latero-apertural view x4900. makes it unusually elusive. Two specimens described earlier (Ogden, 1980) and tentatively identified as Difflugia lacustris, because of their similarity to the description given by Cash & Hopkinson (1909) and especially to one figure (PI. XIX Fig. 1), are now redescribed as D. linearis. Additional specimens, plus the benefit of being able to compare these with specimens of D. lacustris (see p. 9), allows the former identification to be rectified and show that D. linearis is a distinct species. Difflugia linearis can be differentiated from other pyriform species by its distinctive flask-like shape, thin, transparent shell and small aperture. 16 C. G. OGDEN Difflugia manicata Penard, 1 902 DESCRIPTION. The shell is yellow or brown, pyriform, tapering evenly and gradually from a rounded aboral extremity towards the aperture (Fig. 8a). The surface is rough and composed mainly of small to medium pieces of quartz, although the occasional specimen may have large particles added. Small areas of organic cement are seen infrequently, due to the close packing of the shell material, but when present they appear either as strands or as pores in a matrix (Fig. 8c). These pores are about 300 nm in diameter and have an ill-defined inner structure which appears to have smaller pores about 1 30 nm in diameter (Figs. 8c & d). The aperture is circular and surrounded by a distinct pattern of small particles (Fig. 8b). MEASUREMENTS (in um). See Tables 1 and 2. MATERIAL EXAMINED. Specimens were collected from samples taken at three sites, Sphagnum moss gatherings at Holmsley Lodge, Burley, New Forest, Hampshire in March, 1980 and Mynnd Hiraethog, Clwyd, North Wales in August, 1980, and from aquatic plants taken at the banks of the River Brett, near Hadleigh, Suffolk in August, 1979. GEOGRAPHICAL DISTRIBUTION. Austria (Laminger, 1971, 1972c), Belgium (Chardez, 196 \b\ British Isles (Cash el al, 1919; Ogden & Medley, 1980), Congo (Stepanek, 1963), Italy (Grandori & Grandori, 1934), Poland (Moraczewski, 1965; Pateff, 1926, 1927), Switzerland (Penard, 1902). REMARKS. Although this species was thought to be uncommon by Cash, Wailes & Hopkinson (1919), it is suggested that this has been one of the overlooked species and that it will probably be found as one of the most commonly distributed. The wide range of habitat already reported, lake, river and Sphagnum moss would appear to support this opinion. Difflugia minutissima Penard, 1904 Sexangularia minutissima (Penard, 1 904) Deflandre, 1931 DESCRIPTION. The shell is transparent, elongate or ovoid, rounded aborally and tapering slightly towards the aperture (Figs. 9a & c). It is composed of thin flattish pieces of quartz, and the occasional diatom frustule, which are arranged so that they overlap, but the result is still a fragile structure. Only small strands of organic cement have been seen at some junctions. The aperature is basically circular, any variation is usually due to the irregular arrangement of particles around the opening (Fig. 9b). MEASUREMENTS (in urn). See Tables 1 and 2. MATERIALS EXAMINED. Specimens were collected from a sample of Sphagnum moss gathered at Mynnd Hiraethog, Clwyd, North Wales in August 1980. GEOGRAPHICAL DISTRIBUTION Switzerland (Penard, 1904) REMARKS. This species appears to be known only from the initial description (Penard, 1 904), although Deflandre (1931) using Penard's description suggested that it should be transferred to the genus Sexangularia Awerintzew, 1906. The main features of this latter genus are 'chitinous shell, with or without the addition of extraneous particles; polygonal in transverse section, most often hexagonal'. At present it is considered that these features are insufficient to differentiate this genus from Difflugia, and therefore refer the included species to Difflugia-D. minutissima Penard, 1904; D. parvula (Awerintzew, 1906) and D. polydera Deflandre, 1931. The specimens described here were found adhering to extraneous particles when prepared by air-drying and because of this it is not possible to examine them in transverse section, DIFFLUGI A IN BRITAIN 17 nevertheless, they do not appear to be polygonal. The value of this feature in relation to a fragile shell is questionable, especially as Penard's observations would have been carried out on specimens under a cover slip, which would allow a degree of compression. The specimens share similar dimensions to those given by Penard for D. minutissima and are so designated. Difflugia parva (Thomas, 1954) comb. nov. Dijjlugia oblonga var. parva Thomas, 1954 DESCRIPTION. The shell is pyriform, tapering evenly from the swollen and rounded aboral third, to the aperture for the remaining two-thirds (Fig. lOa). It is composed mainly of a mixture of small to medium pieces of quartz, often with the addition of two or three large pieces. Organic cement is seen between particles usually as a series of single units (Fig. 1 Oc), which may overlap but are seldom fused to form a network. Each unit is a ring about 650-750 nm in external diameter, 300-380 nm internal diameter, with walls about 150 nm thick. A small mesh covers the inner portion of each ring (Fig. lOd). The aperture is circular and surrounded mainly by small particles (Fig. lOb). MEASUREMENTS (in urn). See Tables 1 and 2. MATERIAL EXAMINED. Specimens were collected from Sphagnum moss gathered at Matley Bog, Lyndhurst, New Forest, Hampshire in March, 1980; Mynnd Hiraethog, Denbigh, Clwyd, North Wales in August, 1980 and aquatic plants from a pond at Hurley, New Forest, Hampshire in March, 1980. GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Argentina (Lena & Zaidenwerg, 1975), Austria (Laminger, 19736), Belgium (Chardez, 1980; Chardez & Caspar, 1976; Couteaux, 1969), Bulgaria (Golemansky, 1967), France (Thomas, 1954; Thomas & Mabille, 1956), Germany (Schonborn, 1965; Voeltz-Hohn, 1971), Ivory Coast (Gauthier-Lievre & Thomas, 1958), Poland (Golemansky, 1970; Moraczewski, 1965), Venezuela (Grospietsch, 1975). REMARKS. There have been several reports of D. oblonga var. parva since Thomas (1954) described his new variety, although size was the only diagnostic feature used and illustrated (PI. Ill, Fig. 1) by him to differentiate this variety from D. oblonga. The figure given also shows the difference in shell composition, described below as a specific feature. This variety is considered as a distinct species from Z>. oblonga because of its clean outline, relatively smooth surface and detailed cement pattern. Difflugia paulii nom. nov. Difflugia oblonga var. elongata Oye, 1953 DESCRIPTION. The shell is transparent, slim and elongate, tapering evenly from just anterior of the mid-body region towards the aperture, the even-tapering is more apparent in Fig. lib whereas the upper side of Fig. 1 la has a misleading hump, the posterior region is slightly swollen, curving sharply and smoothly at the extremity (Fig. 1 la). It is composed of flattish pieces of quartz to give a smooth appearance, with small areas of organic cement often apparent as part of the matrix (Fig. lie). The cement is in the form of small perforated cones about 600 nm in diameter, the perforations being about 100-1 50 nm in diameter (Fig. 1 Id). The aperture is circular and surrounded by small pieces of quartz (Fig. 1 Ib). MEASUREMENTS (in nm). See Tables 1 and 2. MATERIAL EXAMINED. Specimens were collected from a sample of Sphagnum moss gathered at Mynnd Hiraethog, Denbigh, Clwyd, North Wales in August, 1980. 18 C. G. OGDEN Fig. 10 Difflugia parva: a, lateral view x 710; b, apertural view x 790; c, shell surface showing areas of organic cement x 9800; d, detail of organic cement x 30 000. DIFFLUGIA IN BRITAIN J V * ,. f '^ t RS- .y .-.!'*^i-J*'..3L'^L » .-, Fig. 11 Difflugia paulii: a, lateral view x800; b, apertural view x790; c, portion of shell surface x 4600; d, detail of organic cement x 1 5 000. GEOGRAPHICAL DISTRIBUTION. Austria (Laminger, 19736), Belgium (Oye, 1953), Congo (Gauthier-Lievre & Thomas, 1958), Spain (Gracia, 19720). REMARKS. This species has been described on two occasions, from Belgium by Oye (1953) and from Africa by Gauthier-Lievre & Thomas (1958). Oye (1953) stated that these specimens were slender in comparison with D. lacustris, and considered that this feature and the limited grains of quartz in the shell was sufficient to warrant a new variety. Gauthier- Lievre and Thomas (1958) agreed with this earlier description and designation. Of the more elongated pyriform species, D. paulii in body length appears to occupy a position mid-way between D. linearis and D. lacustris, the present work shows that it is distinct from these two species in outline, elemental composition and patterning of the 20 C. G. OGDEN organic cement, in addition, it can be differentiated from D. linearis by the size of the aperture (Table 1). ETYMOLOGY. This species is named after Dr Paul van Oye whose original description was based on specimens from a pond in Belgium. DifflugiapetricolaCash, 1909 This species has been redescribed recently by Ogden & Fairman (1979). It is reported here only to demonstrate the regularity of dimensions between specimens from different localities, see Tables 1 and 2, because these are often used as taxonomic features. MATERIAL EXAMINED. Specimens were collected from Sphagnum moss gathered at two sites, Holmsley Lodge, Burley, New Forest, Hampshire in March, 1980 and Mynnd Hiraethog, Denbigh, Clwyd, North Wales in August, 1980. Dijflugia pristis Penard, 1902 DESCRIPTION. The shell is brown or opaque, ovoid, tapering from the mid-body position towards the aperture and gracefully curved aborally (Fig. 12a). It is thin, smooth and composed of flattish pieces of quartz (Fig. 1 2a-c) or infrequently including flat pieces of diatom frustule. The particles are packed closely together and only small connections of organic cement are visible (Figs. 12d & e). The aperture is circular with a regular margin (Fig. 12b). MEASUREMENTS (in urn). See Tables 1 and 2. MATERIAL EXAMINED. Specimens were collected from samples of Sphagnum moss gathered at Holmsley Lodge, Burley, New Forest, Hampshire in May, 1978 and at Myndd Hiraethog, Denbigh, Clwyd, North Wales in August, 1980. GEOGRAPHICAL DISTRIBUTION. British Isles (Cash & Hopkinson, 1909), Czechoslovakia (Stepanek, 1967), Hungary (Varga, 1963), Italy (Grandori & Grandori, 1934), Java (BartoS, 1963a), Poland (Moraczewski, 1965), Roumania (Godeanu et al, 1973), Switzerland (Penard, 1902). REMARKS. Cash and Hopkinson (1909) considered their specimens to be in good agreement with Penard's (1902) description, except for the absence of refractive particles that made the shell appear opaque or black. This they attributed to the difference in habitat of their samples, the former being found amongst floating vegetation in clear water and Penard's from a muddy lake bottom. Some differences in size have been reported since Penard who gave 45-65 um as the range of length, Cash and Hopkinson gave 60-65 um, whilst more recently Varga (1963) found specimens measuring 44-48 um in length. The specimens reported here are smaller than any previously described, although in all other respects agree with Penard's description. The main features that distinguish D. pristis from D. pulex are the darker colour and the more regular shape. A single larger specimen, 56 um long, 31um wide, aperture 10 um in diameter, with the typical pyriform shape (Fig. 13a & b) was found in the sample from Wales. This is reported here as being questionably D. pristis (?), being atypical in having a definite neck, the discovery of more specimens may result in a more accurate identification. This specimen is similar to those identified by Cash & Hopkinson (1909) as (?) D. pulex which they described as being 'oval, tapering suddenly to a short neck'. DIFFLUGIA IN BRITAIN 21 J Fig. 12 Difflugia pristis: a, lateral view x2400; b, apertural view x2400; c, alternative view of specimen shown in a., to illustrate regular ovoid shape x 1700; d and e, portions of shell surface with small connections of organic cement (arrowed) x 9300 and x,14J)00. 22 C. G. OGDEN a Fig. 13 Difflugia pristis (?): a, lateral view to show distinct neck x 860; b, apertural view x 1 600. Difflugia pulex Penard, 1902 Difflugia minuta minor Godeanu, 1972 DESCRIPTION. The shell is transparent, elongate or ovoid (Figs. 14a & d). It is composed mainly of a mixture of small thin pieces of flat quartz and pieces of diatom frustule, often with whole frustules or round flagellate cysts adhering to the surface (Figs. 14a-e). The arrangement of these particles is such that only small strands of organic cement are visible. The aperture is usually circular (Fig. 14c) but may vary due to the arrangement of the surrounding particles (Fig. 14b). MEASUREMENTS (in urn). See Tables 1 & 2. MATERIAL EXAMINED Specimens were collected from samples of Sphagnum moss gathered at Subberthwaite, Broughton in Furaess, Cumbria in June 1979 and at Mynnd Hiraethog, Denbigh, Clwyd, North Wales in August, 1980. GEOGRAPHICAL DISTRIBUTION Argentina (Lena & Zaidenwerg, 1975), Australia (Playfair, 1918), Austria (Laminger, J9736), Belgium (Chardez, 19616), British Isles (Cash & Hopkinson, 1909), Congo (Stdpanek, 1963), Czechoslovakia (Stepanek, 1967), Germany (Schonborn, \962a & b), Italy (Grandori & Grandori, 1934; Rampi, 1950), Java (BartoS, 1963a), Netherlands (Hoogenraad & Groot, 1940), Roumania (Godeanu et al, 1972), Spain (Gracia, 19726), United States of America (Laminger et al, 1979), West Africa (Decloitre, 1948). REMARKS. Penard's original description stated that the shell was-' pyriform, with or without narrowing of the mouth, chitinoid, slightly yellow, covered with small scales or particles of amorphous silica, plates, sufficiently transparent to examine the contents' and that specimens rarely exceeded 30 urn in length. Cash & Hopkinson (1909) described specimens between 65-70 urn in length that they tentatively identified as D. pulex, but on the basis of both Penard's and the present description it is now suggested they should be reassigned. The description of D. minuta minor given by Godeanu (1972), shell colourless circular in cross section but with an irregular outline because of added quartz particles and a circular aperture, is so similar to that of D. pulex that it must be considered a synonym. The range of measurements given are also similar to those quoted here (see Table 1 ). Although Penard gave 30 urn as the maximum length for this species, in the described sample two specimens were just in excess of 40 urn and two 30 urn, but in all other respects were similar to the smaller specimens, and all are considered to represent D. pulex. DIFFLUGIA IN BRITAIN Fig. 14 Difflugia pulex: a, lateral view x 1800; b, apertural view of specimen with irregular apertural opening x 1300; c, apertural view of specimen (a.) with circular aperture x 1500; d, lateral view of specimen mainly made of flattish particles x 1600; e, shell surface showing mixture of flat components x 5 100. 24 C. G. OGDEN Difflugia tenuis (Penard, 1 890) comb. nov. Difflugia pyriformis var. tenuis Penard, 1890 Difflugia oblonga var. tenuis Wailes & Penard, 1911 DESCRIPTION. The shell is usually transparent, cylindrical or slightly pyriform, composed of a mixture of mainly small to medium pieces of angular quartz, but with an occasional large particle added (Figs. 15a & b). Sometimes additional particles give a pointed outline to the aboral region, instead of the usual rounded contours. Organic cement is seen frequently as single units between shell components (Fig. 15d), and occasionally in small patches where these units are in a network with a mesh diameter of 350-400 nm and walls 180-220 nm thick (Fig. 1 5e). The mesh surface is characterised by a thin, usually central, inner ring about 1 50-200 nm in diameter (Fig. 15e). The aperture is roughly circular, often having an irregular outline because of the mixture of particles surrounding it (Fig. 1 5b). One specimen with projections similar to the rigid 'filament' structures described by Penard (1890), occurred in the present sample (Fig. 15c). These projections usually arise from a common base, on the surface of the quartz particles, and vary in size and number (Fig. 16a). The projections are about 250 nm in diameter and may be up to 7 um in length, as many as fifteen have been seen sharing a common base (Fig. 1 6b). On the present evidence they seem to be rosettes of bacterial rods rather than the parasitic organisms suggested by Penard (1890). MEASUREMENTS (in urn). See Tables 1 and 2. MATERIAL EXAMINED. Specimens were collected from Sphagnum moss gathered at Holmsley Lodge, Burley, New Forest, Hampshire in March, 1980 and Mynnd Hiraethog, Denbigh, Clwyd, North Wales in August, 1980. GEOGRAPHICAL DISTRIBUTION Argentina (Dioni, 1970), British Isles (Cash et al, 1919), Germany (Penard, 1 890), Poland (Golemansky, 1970), Venezuela (Grospietsch, 1975). REMARKS. Although the specimens described here are a little longer than those reported by Penard (1890) they are otherwise in good agreement with his description. This species has been identified previously on only a few occasions, but this may be due to its being mistaken for the more common species in this size range, for example D. penardi and D. rubescens. There remains the question of specific biological requirements, food, temperature, pH etc., which may be the reason why although the site at Holmsley has been sampled regularly for five or six years, March 1980 was the first time that this species has been seen there and then it appeared in significant numbers. This species is distinguished by its shape, size of aperture and the pattern of the organic cement. Difflugia viscidula Penard, 1 902 DESCRIPTION. This species has been redescribed recently by Ogden & Hedley (1980) but is reported again with some additional information. The shell is opaque, pyriform or elongate ovoid, aborally it is usually rounded (Fig. 17a) but may occasionally be pointed. It is composed of a mixture of different sizes of angular quartz, with organic cement seen infrequently as part of the surface matrix. The cement appears as single units squashed together so that they are adjacent or overlap (Fig. 1 7c). The aperture is circular and usually surrounded by small particles which give it a characteristic well-defined outline (Fig. 17b). The illustrated aperture has a cyst plug, which although broken at one edge has in general a smooth surface, suggesting that it is mainly organic but reinforced by particles of quartz. About 10% of the examined specimens had an apertural cyst plug. MEASUREMENTS (in um). See Tables 1 and 2. DIFFLUGIA IN BRITAIN 25 Fig. 15 Difflugia tennis: a, lateral view x 1000, b, apertural view x780; c, specimen with 'filament-like' structures projecting from the surface x 780; d, shell surface showing small areas of organic cement x 8 100; e, detail of organic cement network x 24 000. 26 C. G. OGDEN Fig. 16 Difflugia tennis: a, portion of shell surface to show distribution of 'filament-like' structures x2500; b, rosette of 'filaments', tentatively identified as bacterial rods x 7000. MATERIAL EXAMINED Specimens were collected from a sample of Sphagnum moss gathered at Holmsley Lodge, Burley, New Forest, Hampshire in March, 1980. GEOGRAPHICAL DISTRIBUTION. Argentina (Boltovskoy & Lena, 1974), Austria (Laminger, 1971), British Isles (Ogden & Hedley, 1980), Germany (Schonborn, \962a, 1965, 1975), Java (BartoS, 1963a),Roumania(Godeanu^0/., 1973), Switzerland (Penard, 1902). REMARKS. The present material extends the measurements we gave previously (Ogden & Hedley, 1980) to encompass those given by Penard (1902). There remains the problem of priority of names for these specimens because Penard (1902) described two distinct species, namely D. lemani Blanc, 1892 and D. viscidula sp. nov., which he differentiated mainly on size; the former being 50-85 um long (three individuals were 100-200 um) and the latter 180-260 um long. When he later found (Penard, 1905) that he had used incorrect measure- ments for D. lemani he suggested that D. viscidula should be regarded as a synonym. However, this proposal left his description of specimens under the name D. leman /-Penard, 1902 p. 249, without a proper designated name. They were divided into two series, the first slim, between 75-85 um long and the second wider, but smaller about 50 urn long. It would appear that no subsequent report has rectified this situation, and it would seem that now is too late to change this because of the proliferation of species that have since been described and fall within the size range of the earlier description. Furthermore, it appears that Blanc's (1892) original description of D. lemanii might contravene Article 8 of the International Code of Zoological Nomenclature, because when first issued it would seem that it was not available by purchase or free distribution. There are no records of this publication in either this Museum's Libraries nor in the British Library, although I have recently obtained a photocopy from the Universitaire Lausanne. In Blanc's initial description of D. lemanii the shell dimensions varied as follows: body length between 180-310 um, breadth 130-150 um. and the aperture diameter was given as 1 lOum, it had a cylindrical body with almost parallel sides and the composition was such that it was friable and delicate. These measurements are in good agreement with Penard's 180-260 um body length for D. viscidula, and those given here in Table 1 except for the diameter of the aperture, this latter feature is given as being equal to about half the breadth of the shell by Penard (1905). The diameter of the aperture and the pyriform rather than cylindrical shape of the body are considered sufficient to differentiate the present specimens and those of Penard (1902, 1905) from D. lemanii Blanc, 1892. This therefore leaves Penard's designated name of D. viscidula as valid and the specimens described here are so named. DIFFLUGIA IN BRITAIN 27 Fig. 17 Difflugia viscidula: a, lateral view x410; b, detail of aperture which is blocked by a cyst plug x 1000; c, detail of organic cement x 13 000. Pointed species or those with protruberances Difflugia amphoralis Cash & Hopkinson, 1 909 DESCRIPTION. The shell is transparent, squat pyriform with the aboral extremity tapering evenly to a point (Figs. 19a & b). It is composed mainly of medium pieces of quartz with small pieces mixed and so arranged to produce an intermediate smooth surface. Organic cement is seen in small patches between particles (Fig. 19d) and appears as rings fused to linearis I \gassowskii/ \ bryophila I V petricola Fig. 18 Diagrams of pyriform and elongate species to illustrate the basic, outline based on measurements given in Table 2. Table 2 Average dimensions of pyriform specimens listed in Table 1 and illustrated in Fig. 18. Species Length Breadth Diameter of aperture D. minutissima 9 7 3 D. pulex 32 25 8 D. pristis 37 25 11 D. glans 71 46 20 D. manicata 77 47 16 D. tennis 77 44 23 D. linearis 100 35 12 D. gassowskii 102 50 18 D. bryophila 108 58 19 D. petricola 111 72 25 D. paulii 126 50 21 D. lanceolata 128 64 25 D. parva 149 75 24 D. lacustris 183 78 34 D. cylindrus 211 112 45 D. viscidula 217 161 66 DIFFLUGIA IN BRITAIN 29 Fig. 19 Difflugia amphoralis: a, lateral view x850; b, lateral view to show even aboral tapering x 500; c, apertural view x 760; d, shell surface showing areas of organic cement x 4500; e, detail of organic cement network x 24 000. 30 C. G. OGDEN form a network, each mesh of which is about 380-450 nm internal diameter and the raised walls are 130 nm thick, a smooth membrane covers each enclosure (Fig. 19c). The circular aperture is surrounded by a small rim of mainly small particles to give a poorly defined border (Figs. 19a,b&c). MEASUREMENTS (in urn). A single specimen: body length 109, breadth 62, diameter of aperture 28. MATERIAL EXAMINED. The specimen was found in Sphagnum moss gathered at Holmsley Lodge, Burley, New Forest, Hampshire in March, 1980. GEOGRAPHICAL DISTRIBUTION. British Isles (Cash & Hopkinson, 1909), Tashkent (Pashintowa, 1929). REMARKS. The structure of the shell in the present specimen differs from the original (Cash & Hopkinson, 1909) by being composed mainly of quartz particles, rather than 'amorphous (?siliceous) scales'. However, it should be noted that the specimens described by Leidy (1879) and quoted as synonyms of this species by Cash & Hopkinson (1909) are also composed mainly of 'quartz sand'. Difflugia bicruris Gauthier-Lievre & Thomas, 1958 DESCRIPTION. The shell is elongate ovoid, the sides being almost parallel with a slight tapering towards the aperture and the aboral extremity, the latter is rounded and has two small, equally spaced, protruberances or horns (Figs. 20a & c). It is composed of medium to large pieces of angular quartz, with some small particles being used in shaping the horns (Fig. 20d). The surface is rough but patches of organic cement are seen to form part of the shell matrix (Fig. 20e). Organic cement is arranged in the form of a regular network whose mesh has a diameter of about 300-350 nm and the distance between each enclosure is about 300 nm (Fig. 20f). The aperture is circular and surrounded by an even arrangement of small particles (Fig. 20b). MEASUREMENTS (in um). Two specimens: body length 202-207, breadth 95-1 1 5, diameter of aperture 4 1-5 8. MATERIAL EXAMINED. Specimens were collected from aquatic plants taken at the banks of the River Brett, near Hadleigh, Suffolk, in August, 1979. GEOGRAPHICAL DISTRIBUTION Ivory Coast (Gauthier-Lievre & Thomas, 1958), Poland (Golemansky, 1970). REMARKS. Slight differences exist between the present specimens and those described by Gauthier-Lievre & Thomas (1958). They have slightly larger general body measurements, although the proportions are directly comparable, and the horns are reduced in length, 20 urn here compared with 30-33 um in the African specimens. Nevertheless, the descriptions are in good agreement showing that D. bicruris is distinctly ovoid with two aboral spines or horns. Difflugia distenda nom. nov. Difflugia acuminata var. inflata Penard, 1899 DESCRIPTION. The shell is transparent, pyriform with the aboral extremity acutely curved towards a small central tubular horn (Fig. 2 la), although the extent of the angle may be less acute in a few specimens. It has an intermediate smooth surface and thickness, being composed mainly of small to medium pieces of quartz, with occasional diatom frustules added. Areas of organic cement are sometimes seen in the shell matrix as a network (Fig. 21c), with a mesh 350-400 nm in diameter and walls 150-200 nm thick (Fig. 21d). The DIFFLUGIA IN BRITAIN Fig. 20 Difflugia bicruris: a, lateral view illustrating the two aboral horns x 420; b, apertural view x400; c, alternative lateral view with aboral horns not easily seen x430; d, detail of aboral horn x2500; e, portion of shell surface showing distribution of organic cement x2700; f, detail of organic cement network x 25 000. C. G. OGDEN Fig. 21 Difflugia distenda: a, lateral view to show small aboral horn x430; b, apertural view x350; c, shell surface showing large areas of organic cement x2400; d, detail of organic cement network x 1 1 000. aperture is circular and usually surrounded by an even arrangement of small particles (Fig. 21b). MEASUREMENTS (in urn). Based on ten specimens: body length 217-270, breadth 109-135, diameter of aperture, 58-64; B/L 0-53 ±0-04, d/L 0-26 ±0-02. MATERIAL EXAMINED. Specimens were collected from a sample of Sphagnum moss gathered at Holmsley Lodge, Burley, New Forest, Hampshire in March, 1980. DIFFLUGIA IN BRITAIN 33 GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Austria (Laminger, 1971, 19736), Belgium (Chardez, 196 la), British Isles (Cash & Hopkinson, 1909), Congo (Chardez, 1964; Gauthier-Lievre & Thomas, 1958), France (Deflandre, 19626; Thomas & Mabille, 1956), Gabon (Gauthier-Lievre & Thomas, 1958), Ivory Coast (Gauthier-Lievre & Thomas, 1958), Mexico (Laminger, 19736), Morocco (Gauthier-Lievre & Thomas, 1958), Poland (Golemansky, 1970; Moraczewski, 1965), Switzerland (Penard, 1902), Tashkent (Pashintowa, 1967). REMARKS. The variations of D. acuminata, and its twelve varieties has recently been illustrated by Chardez (1961). More recently it has been shown (Ogden, 1979) that D. acuminata Ehrenberg, 1838 has a distinctive elongate shape and an apparently unique organic cement pattern. Specimens described as var. inflata differ from this species in shape, size and organic cement pattern, the former is clearly demonstrated when the measurements are expressed as ratios, the comparable ratios for D. acuminata are B/L 0-36 ±0-03 and d/L 0-1 5 ±0-03 (Ogden, 1979). The specimens described here agree well with Penard's (1899, 1902) original descriptions, and the differences from D. acuminata are considered sufficient to warrant specific designation. Our normal practise is to raise the variety name to specific rank, but on this occasion it is impracticable as the terminology inflata has been used several times in connection with specimens of Difflugia, for example D. curvicaulis var. inflata Decloitre, 1951. ETYMOLOGY The specific name has been selected to reflect the inflated condition of the shell (L. distenda = swell out). Difflugia labiosa Wailes, 1919 Difflugia amphora Leidy 1879 of Penard, 1901; 1902 & 1905 DESCRIPTION. The shell is opaque or dark brown, ovid or elongate ovoid, tapering from the mid-body region sharply to the rounded or pointed aboral extremity and more gradually towards the aperture (Fig. 22a). It is relatively thick and composed of quartz pieces so arranged that small particles fill the interstices between the larger pieces which form a mainly smooth surface (Fig. 22d). Organic cement is seen infrequently but is in the form of a network, each mesh being about 250-350 nm in diameter and is usually covered by a smooth membrane (Fig. 22e). The aperture is roughly circular but is sinuous with as many as six or seven undulations or lobes (Fig. 22b). It is slightly recessed into the main body, as though it was surrounded by a groove, the margin or lips, are thin and bordered by tiny particles of quartz. (Fig. 22b & c). MEASUREMENTS (in um). Based on five specimens: body length 150-21 1, breadth 112-158, diameter of aperture 50-63. MATERIAL EXAMINED. Specimens were collected from aquatic plants taken at the banks of the River Brett, near Hadleigh, Suffolk in August, 1979. GEOGRAPHICAL DISTRIBUTION. Austria (Laminger, 1971, 1975), Belgium (Chardez, 1980), British Isles (Cash et al, 1919; Ogden & Hedley, 1980), Czechoslovakia (Ertl, 1965; Stepanek, 1952, 1967), France (Thomas, 1954; Thomas & Mabille, 1956), Germany (Grospietsch, 1958; Schonborn, 19620, & 6), Netherlands (Hoogenraad & Groot, 1940), Poland (Moraczewski, 1961, 1965), Russia (Kourov, 1925), South Africa (Oye, 1931), Switzerland (Penard, 1902), Venezuela (Deflandre 1926a; Grospietsch, 1975). REMARKS. There has been some confusion over the correct name for this species, most recent authors using D. amphora Leidy, 1879, basing their identifications on the description given by Penard (1902). However, this name is preoccupied as it was used by Ehrenberg (1854, 1872) to describe a specimen which is no longer considered to be a species of Difflugia. It 34 C. G. OGDEN •? • ** v fc:4-^"""X- . Fig. 22 Difflugia labiosa: a, latero-apertural view to show arrangement of particles x 580; b, apertural view illustrating the undulations or lobes x470; c, lateral view of aperture to show slight groove and small particles on margin x990; d, portion of shell surface showing the close packing of particles x 1 300; e, detail of organic cement x 24 000. DIFFLUGIA IN BRITAIN 35 follows that the later reports by Leidy (1874, 1879) default for the same reason. The latter report being more confusing by quoting D. amphora as a synonym of D. urceolata, whilst giving a figure of D. ureceolata var. amphora. Wailes (in Cash et ai, 1919) noted these earlier reports and proposed the new name D. labiosa, giving Penard's (1901 , 1902, 1905) reports as synonyms. Earlier, Cash & Hopkinson (1909) had suggested that part of Leidy 's (1879) description of/), urceolata var. amphora was a synonym of their new species D. amphoralis. The specimens described here are in good agreement with Penard (1902) who gave a range of body lengths 150-270 urn, but usually about 200-210 urn, and Wailes who suggested that it was a rare species from his single 265 um long specimen. This species is distinct in its ovoid-conical shape plus the lobed aperture with distinct margin and recessed base. Difftugia mamillaris Penard, 1 893 DESCRIPTION. The shell is colourless or hyaline, ovoid elongate, swollen or arched in the mid-region but tapering at both extremities, to give a rounded protruberance aborally and gradually near the aperture to give a slightly pronounced neck (Fig. 23a). Irregularities in general shape are not uncommon, for example one specimen although tapered did not have an aboral protruberance, whilst another (Fig. 23c) tapered markedly from the mid-body region. It is composed mainly of small to medium pieces of quartz so arranged that the larger particles tend to be in the mid-body region whilst the extremities have the smaller particles, overall it usually produces an intermediate thickness of a single layer and a relatively smooth outline. Organic cement occurs in small patches as a network, which has walls about 80-1 30 um thick between each mesh but sometimes 230 um thick at junctions. Each mesh is about 250nm in diameter and is covered by a smooth membrane which is distinct in having three or four small white spots on the surface of each enclosure (Figs. 23d & e). The aperture is circular, composed of small particles, and roughly finished so that the margin appears uneven or serrated (Fig. 23b). MEASUREMENTS (in um). Based on twenty-three specimens: body length 93-111, breadth 54-72, diameter of aperture 23-3 1 . MATERIAL EXAMINED. Specimens were collected from a sample of aquatic plants taken at the banks of the River Brett, near Hadleigh, Suffolk in August, 1979. GEOGRAPHICAL DISTRIBUTION. Austria (Laminger, 1975), Congo (Chardez, 1964), Czechoslovakia (St6panek, 1967), Germany (Grospietsch, 1957), Switzerland, (Penard, 1901), Venezuela (Grospietsch, 1975). REMARKS. This species was initially described by Penard (1893) and redescribed in more detail by the same author (Penard, 1 902). The present specimens are in good agreement with the latter description, including measurements which gave the body length as being generally between 90-110 um with a few large specimens up to 130 um long. More recently, Grospietch (1957) has shown a similar regularity in size of specimens from Lake Maggiore, giving length 90-1 13 um and breadth 48-63 urn. Penard (1902) suggested that this species was rare in Swiss Lakes, and this appears to be the case in other localities judging by its reported incidence. Nevertheless, if the two recent reports (Grospietch, 1957 and the present) are used as indicators, it would appear that when present this species is usually abundant. D. mamillaris is distinct in outline, even though the thin structure may be subject to distortion, and the unusual organic cement pattern. Difftugia microdaviformis (Kourov, 1925) comb. nov. Difflugia oblonga var. microdaviformis Kourov, 1925 DESCRIPTION. The shell is brown, pyriform with a distinct aboral protruberance (Fig. 24a). It 36 C. G. OGDEN w^S, * a Fig. 23 Difflugia mamillaris: a, lateral view x 1 100; b, apertural view x 790; c, lateral view of irregular shaped shell x 440; d and e, detail of organic cement network, note the small white spots in each enclosure which is a regular feature x 24 000. DIFFLUGIA IN BRITAIN Fig. 24 Difflugia microclaviformis: a, lateral view x 230, b, apertural view x 530; c, shell surface illustrating the arrangement of particles and organic cement x2600; d, detail of organic cement network, note the regular distribution of small pores in each enclosure x 33 000. is composed of small to medium pieces of quartz, some flattish diatom frustules, and a network of organic cement is often seen as part of the shell matrix (Fig. 24c). The result is a smooth surface and a well defined outline. The mesh of the organic cement has a diameter of 300 nm with walls 150nm thick, and a smaller network, with pores about 30 nm in diameter, covers each mesh enclosure (Fig. 24d). The aperture is circular and surrounded by small particles (Fig. 24b). 38 C. G. OGDEN MEASUREMENTS (in um). Based on two specimens: body length 202-206, breadth 88-89, diameter of aperture 27-28. MATERIAL EXAMINED. Specimens were collected from a sample of Sphagnum moss gathered at Holmsley Lodge, Burley, New Forest, Hampshire, in March, 1980. GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Argentina (Vucetich, 1978), Austria (Laminger, 19736), Congo (Gauthier-Lievre & Thomas, 1958), France (Thomas, 1954), Ivory Coast (Gauthier-Lievre & Thomas, 1958), Mexico (Laminger, 1973a), Roumania (Godeanu et al, 1973), Russia (Kourov, 1925), Spain (Gracia, 1972a). REMARKS. This species when initially described (Kourov, 1925) had a body length not greater than 185 urn, whereas Gauthier-Lievre & Thomas, 1958 gave dimensions similar to those given here. It is redescribed to show its marked similarity to D. claviformis, lack of material prevents a complete comparison and the identification must be treated as tentative. D. microclaviformis appears to differ from D. claviformis (see Ogden, 1979) in size and possibly the organic cement pattern. Difflugia molesta Penard, 1902 DESCRIPTION. The shell is brown, ovoid or ovoid-elongate, sometimes with a small apertural collar and arched aborally (Fig. 25a). It is composed of a mixture of quartz particles and diatom frustules, the former usually being predominant. Organic cement is seen as a network between particles, either as part of the shell matrix or occasionally at junctions. The rings that form the network are about 650-750 nm internal diameter with the dividing wall being 100-1 50 nm thick, a second thin, inner wall lies close to the main wall and in the illustrated specimen the covering membrane is either holed or figured (Fig. 25c). The aperture is roughly circular, irregular in outline, and mainly surrounded by small particles (Fig. 25b). MEASUREMENTS (in um). Based on four specimens: body length 106-114, breadth 61-87, diameter of aperture 28-43. MATERIAL EXAMINED. Specimens were collected from Sphagnum moss gathered at Holmsley Lodge, Burley, New Forest, Hampshire in March, 1980 and Mynnd Hiraethog, Denbigh, Clwyd, North Wales in August, 1980. GEOGRAPHICAL DISTRIBUTION. Roumania (Godeanu et al, 1973), Russia (Kourov, 1925), Switzerland (Penard, 1902). REMARKS. These specimens are tentatively identified here as D. molesta, the query arising due to their similarity with D. amphoralis. Of the four specimens examined, the smallest (Fig. 25a) bears the closest resemblance being slim, with a small aperture and differing in the absence of a pointed aboral protruberance. The three broader specimens have a wider aperture, a narrow neck and are arched aborally. In addition, there are differences in the organic cement patterns between the two species, but altogether there is insufficient information to satisfactorily resolve the problem. Difflugia tricornis (Jung, 1936) comb. nov. Difflugia elegans forma tricornis Jung, 1936 DESCRIPTION. The shell is pyriform, with a slight broadening near the aperture, and is characterised by three, evenly spaced, aboral spines (Fig. 26a). The surface is rough and mainly composed of a mixture of medium and large pieces of angular quartz, the spines have medium particles at their wide bases but small particles are used progressively as they taper to a point. Small areas of organic cement are seen between the particles (Fig. 26c), usually in the form of a regular network (Fig. 26d), having a mesh between 350^00 nm internal DIFFLUGIA IN BRITAIN 39 Fig. 25 Difflugia molesta: a, lateral view x910; b, apertural view x740; c, detail of organic cement to show arrangement of rings and figured centre x 24 000. diameter and dividing walls about 1 50 nm thick although at some junctions there are larger areas. The aperture is circular and surrounded by an irregular assortment of particles (Fig. 26b). MEASUREMENTS (in um). One specimen: body length 1 16, breadth 82, diameter of aperture 40. 40 C. G. OGDEN Fig. 26 Dijjlugia tricornis: a, lateral view to show the three equally spaced aboral spines x 690; b, apertural view x 530; c, portion of shell surface showing small areas of organic cement x2300; d, detail of organic cement network x 14 000. MATERIAL EXAMINED. The specimen was collected from aquatic plants taken at the banks of the River Brett, near Hadleigh, Suffolk in August, 1979. GEOGRAPHICAL DISTRIBUTION. Germany (Jung, 1936), Sudan (Gauthier-Lievre & Thomas, 1958). REMARKS. In the earlier descriptions (Jung, 1936; Gauthier-Lievre & Thomas, 1958) the specimens resembled D. elegans except for the three aboral spines which were stated to be randomly placed, although Jung (1936) cited Penard's figures referring to much smaller animals. Differences in the shape and structure of D. elegans examined recently by the DIFFLUGI A IN BRITAIN 41 author (Ogden, 1979; Ogden & Hedley, 1980) have been confined to the size and structure of the single aboral spine or horn, whilst the body length was usually of a standard size 110-160 jim. The present specimen has three, equally spaced, aboral spines and the body breadth is markedly wider, features that are considered sufficiently different from D. elegans to warrant a specific designation. The earlier reports are placed, with reservations, in synonymy. Difflugia ventricosa Deflandre, 1926 DESCRIPTION. The shell is colourless, elongate, with a slight swelling in the aboral half of the body which then tapers to a sharp point (Fig. 27a). It is composed of a mixture of quartz, diatom frustules and flagellate cysts to give a thin, irregular surface. Organic cement is frequently seen between particles in the form of a network (Fig. 27c), made of rings about 600-680 nm in diameter with walls 1 80-250 nm thick (Fig. 27d). In some instances the rings are fused and appear to have lost or merged their walls (Fig. 27e). The aperture is circular and usually surrounded by small particles (Fig. 27b). MEASUREMENTS (in urn). Two specimens: body length 177-199, breadth 64-66, diameter of aperture 30-3 1 . MATERIAL EXAMINED. The specimens were collected from a sample of Sphagnum moss gathered at Holmsley Lodge, Burley, New Forest, Hampshire in March, 1 980. GEOGRAPHICAL DISTRIBUTION. Belgium (Chardez, 1973), Congo (Gauthier-Lievre & Thomas, 1958), France (Thomas & Mabille, 1956), Ivory Coast (Gauthier-Lievre & Thomas, 1958), Venezuela (Deflandre, 1926a). REMARKS. A redescription of D. ventricosa has recently been given by Chardez (1973) who compared it with other species having a pointed aboral extremity. It is interesting to note that he made no comparison with D. venusta, although from the description given here (below) there would seem to be some similarities. The tabulated measurements given by Chardez (1973) from earlier descriptions, are in good agreement with the exception of those given by Thomas & Mabille (1956). This species is distinct in having a thin, elongate outline which is sharply pointed aborally. Difflugia venusta (Penard, 1902) comb. nov. Difflugia pyriformis var. venusta Penard, 1902 Difflugia oblonga var. venusta (Penard, 1902) Cash & Hopkinson, 1909 DESCRIPTION. The shell is pale yellow or hyaline, cylindrical, gradually swelling from the aperture for about two-thirds of the body length to the broadest diameter and then tapering sharply in the last third to the bluntly pointed apex (Fig. 28a & b). It is composed mainly of small to medium pieces of quartz and diatom frustules arranged to give a relatively regular, intermediate smooth, outline apart from the occasional addition of a larger angular piece of quartz or diatom frustule. Small areas of organic cement are sometimes visible as a thick walled network with a covered mesh (Fig. 28d), but more often as thick walled rings about 450-600 nm in diameter and walls 150-220 nm (Fig. 28c). The aperture is usually circular and surrounded by small particles that give it an irregular margin (Fig. 28c). MEASUREMENTS (in um). Based on three specimens: body length 174-188, breadth 68-76, diameter of aperture 30-32. MATERIAL EXAMINED. Specimens were collected from a sample of Sphagnum moss gathered at Holmsley Lodge, Burley, New Forest, Hampshire in March, 1980. GEOGRAPHICAL DISTRIBUTION. Argentina (Dioni, 1970), Belgium (Chardez & Caspar, 1976), 42 C. G. OGDEN . a Fig. 27 Difflugia ventricosa: a, lateral view to illustrate tapering of aboral spine x 520; b, apertural view x 760; c, shell surface showing small areas of organic cement x4700; d, detail of organic cement network of rings x 24 000; e, organic cement network with fused rings x 28 000. DIFFLUGIA IN BRITAIN 43 Fig. 28 Difflugia venusta: a and b, lateral views to show sharp tapering of aboral region x570 and x340; c, apertural view x590; d, shell surface showing distribution of organic cement x 9200; e, detail of organic cement network x 24 000. 44 C. G. OGDEN mamillaris / \ amphoralis Fig. 29 Diagrams of pointed species or those with protruberances to illustrate the basic outline, based on measurements given in Table 3. DIFFLUGIA IN BRITAIN 45 Table 3 Average dimensions of pointed species or those with protruberances used to give basic outlines illustrated in Fig. 29 Species Length Breadth Diameter of aperture D. mamillaris 103 65 27 D. amphoralis 109 62 32 D. molesta 110 73 37 D. tricornis 116 82 40 D. labiosa 183 132 55 D. venusta 179 71 31 D. ventricosa 188 65 30 D. microclavi- formis 204 88 27 D. bicruris 205 106 50 D. distenda 230 122 60 France (Thomas, 1954), Haute Volta, W. Africa (Gauthier-Lievre & Thomas, 1958), Switzerland (Penard, 1902). REMARKS. The present specimens agree well with the descriptions given by Penard (1902), Cash & Hopkinson (1909) and Gauthier-Lievre & Thomas (1958) who considered it a variety of D. pyriformis/oblonga, although the shells described by Cash & Hopkinson (1909) were slimmer than those reported here and by Gauthier-Lievre & Thomas (1958). This species is distinct in the graceful outline with bluntly pointed aboral extremity and shell structure. Ovoid or spherical species Difflugia ampullula Playfair, 1918 DESCRIPTION. The shell is hyaline, ovoid and circular in cross section (Fig. 30a). It has a medium thickness and is composed mainly of small to medium pieces of quartz, arranged to give a clean outline with a smooth surface. Small areas of organic cement in the form of a network, are often seen as part of the shell structure (Fig. 30d). The mesh of the network is small about 300-350 nm in diameter with thin walls 50-100 nm thick, and an even smaller distinctive network covering each mesh enclosure (Figs. 30e & f)- The aperture is circular, surrounded by a slightly raised collar of small particles, and the edge of the collar is often irregular (Figs. 30b & c). MEASUREMENTS (in urn). Range of 39 specimens: body length 54-95, breadth 35-72, diameter of aperture 16-29. MATERIAL EXAMINED. Specimens were collected from aquatic plants taken at the banks of the River Brett, near Hadleigh, Suffolk in August, 1979. GEOGRAPHICAL DISTRIBUTION. Australia (Playfair, 1918). REMARKS. The specimens described here differ slightly from the original description (Playfair, 1918) in the absence of a 'minute, pointed apiculate process' on the aboral extremity. However, this process was reported as being present sometimes, and as there is otherwise good agreement between the two reports, the specimens are designated as D. ampullula. 46 C. G. OGDEN Fig. 30 Difflugia ampullula: a, lateral view x 1000; b, latero-apertural view of aperture to illustrate the small collar x 1200; c, apertural view x 770; d, portion of shell surface to show the arrangement of particles and organic cement x5000; e, detail of shell surface x7700; f, small area of organic cement network, note that each enclosure has an inner network x 25 000. DIFFLUGIA IN BRITAIN 47 Dijflugia angulostoma Gauthier-Lievre & Thomas, 1958 DESCRIPTION. The shell is transparent, spherical and composed mainly of diatom frustules (Fig. 3 la & b). The particles are packed close together with many overlapping, to give a rough surface. Organic cement is seen infrequently as small strands between particles (Fig. 3 Ic). The aperture is usually circular (Fig. 3 la), but it may have irregularities depending on the arrangement of surrounding diatom frustules. Two groups of specimens with identical shell features but differing dimensions were examined, the 'a' specimens are from all four listed localities and 'b' specimens are from Three Shires Stone only. * MEASUREMENTS (in urn) body diameter of length breadth aperture B/L d/L 8 specimens 'a' 40-56 40-48 18-23 0-94 ±0-06 0-42 ±0-06 8 specimens 'b' 60-82 50-73 28-51 0-87±0-09 0-56±0-05 MATERIAL EXAMINED. Specimens were collected from samples of Sphagnum moss gathered at four localities: Cranes Moor in May, 1977, Holmsley in May, 1978 both in the New Forest, Hampshire; Three Shires Stone, Wrynose Pass and Lanthwaite, both in Cumbria, June, 1979. GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Argentina (Vucetich, \913a & b), Congo (Gauthier-Lievre & Thomas, 1958). REMARKS. This species was described by Gauthier-Lievre & Thomas (1958), from specimens found in Algeria, who considered that it differed from D. minuta by the large size of the aperture, quoted as being about one-third of the breadth in diameter, and the covering diatoms. Both sets of the present specimens, 'a' and 'b', agree well with this description, having a large aperture about half the breadth diameter and are composed of diatoms. The 'b' specimens share almost similar dimensions to D. angulostoma, the latter having a body length 60-95 um and aperture 30-45 um, whereas the 'a' specimens are generally smaller. The difference in size between specimens 'a' and 'b' is more apparent when the ratios d/L are compared, such differences are usually significant. However, lack of similar data from the original description of D. angulostoma does not allow a comparison to be made. In the absence of this information and the otherwise similarity of the two groups of specimens, they are both designated as D. angulostoma. Dijflugia decloitrei Godeanu, 1972 Difflugia levanderi Playfair, 1918 (in part) Difflugia acuminata Levander, 1 894 (in part) DESCRIPTION. The shell is transparent, ovoid, tapering evenly from the mid-body position towards the aperture and aboral extremity, there is the suggestion of a collar near the aperture due to the tapering ending prior to the apertural opening (Fig. 32a). In some specimens there is an apparent lateral compression, but it is usually slight and probably related to the fragility of the structure. It has a well defined outline, and the arrangement of flattish pieces of quartz give it a smooth surface. A network of organic cement is seen at most junctions of these particles (Fig. 32c). The mesh is about 280-350 nm in diameter and the walls 350 nm thick (Fig. 32d). The aperture is circular with often a rugged outline due to the placement of the flattish particles (Fig. 32b). MEASUREMENTS (in |im). Based on ten specimens: body length 77-95, breadth 39-55, diameter of aperture 20-27. C. G. OGDEN Fig. 31 DiJJlugia angulostoma: a, apertural view x 1600; b, lateral view, note the covering diatom frustules x 1000; c, shell surface with strands of organic cement x 8700. MATERIAL EXAMINED. Specimens were collected from a sample of Sphagnum moss gathered at Myndd Hiraethog, Denbigh, Clywdd, North Wales in August, 1980. GEOGRAPHICAL DISTRIBUTION. Australia (Playfair, 1918), Germany (Levander, 1894), Roumania (Godeanu, 1972). REMARKS. Levander (1894) described four different forms of D. acuminata, one of which-type 'b'-was considered by Playfair (1918) to represent a distinct species., D. ievanderi. Both of these authors suggested that there were two sizes of these specimens, '110x60 and 70x40um', the larger being rough and 'stony' whilst the smaller were chitinous with small, scattered granules. Recent descriptions of D. Ievanderi, for example DIFFLUGIA IN BRITAIN 49 Fig. 32 Difflugia decloitrei: a, lateral view x 1 300; b, apertural view x 900; c, portion of shell to show arrangement of flat particles to give a smooth surface x2400; d, detail of organic cement network x 22 000. that given by Gauthier-Lievre & Thomas (1958) stated a range of body length of 85-140 ^m suggesting that these are the larger specimens of the earlier authors. The specimens described by Godeanu (1972) as D. decloitrei appear to be similar to the group of smaller specimens, having a similar structure and large aperture. Those described here are in good agreement with this latter description and share similar measurements; body length 62-86 breadth 40-56 and diameter of aperture 20-23 (Godeanu, 1972). In the absence of larger shells for comparison the present specimens are referred to D. decloitrei. 50 C. G. OGDEN Difflugia gramen Penard, 1 902 This species has recently been redescribed (Ogden, 1980), but is included here because the numbers examined allow a comparison of dimensions between specimens from different habitats and localities. Both samples were collected in August, 1979, from sites which are about fifty miles apart. Specimens 'A' were selected from a sample of algae and water plants in stationary water (see Ogden, 1980), specimens 'B' from aquatic plants at the banks of the River Brett, near Hadleigh Suffolk, which in summer is a slow moving, small watercourse. MEASUREMENTS (in urn). 'A' thirty-five specimens; 'B' forty-four specimens. body diameter of length breadth aperture B/L d/L d/B 'A' 89-117 70-112 23-39 0-96±0-07 0-34±0-04 0-36 + 0-03 'B' 61-97 42-75 18-33 0-77±0-07 0-32±0-04 0-43 ±0-04 avg. 4A' 98-8 94-3 33-6 avg. 'B' 78-7 60-5 26-2 REMARKS. In shell construction the 'A' specimens are larger, spherical and more regular, only one aperture not appearing typically trilobed. Whilst, 'B' specimens are ovoid and nine (about 20%) had four lobes or were irregular in outline. It is interesting to note that the common feature between these specimens is the ratio of the aperture to the body length. Difflugia masaruzzi Oye, 1958 DESCRIPTION. The shell is transparent, ovoid and composed of a mixture of flattish siliceous particles including some diatom frustules, to give a fragile structure with an irregular surface and outline (Fig. 33a). Organic cement is seen at some junctions (Fig. 33c), but there is a degree of overlapping with most particles. It appears as a network having a mesh of about 450-600 nm in diameter with walls 200 nm thick, each enclosure having a smaller network with a mesh about 90 nm in diameter (Fig. 33d). The aperture is circular, wide, usually with an irregular margin (Fig. 33b). MEASUREMENTS, (in um). Two specimens: body length 66-67, breadth 39^43, diameter of aperture 25. MATERIAL EXAMINED. Specimens were collected from a sample of aquatic plants taken from the edge of a pond at Burley, New Forest, Hampshire in March, 1980. GEOGRAPHICAL DISTRIBUTION. Congo (Oye, 1958), 'Costa Rica (Laminger, 1973a), Mexico (Laminger, 1973a). REMARKS. In the initial description of D. mazaruzii it was stated by Oye (1958) to be similar to D. rubescens and D. lucida, although it only shares a transparent shell with these two species. The present specimens agree well with his description of a shell having some large distinct particles attached, and an aperture devoid of a regular margin more or less wavy because parts of the shell extend to the edge. Two specimens formed the basis for the earlier report and were somewhat larger, 72 and 78 |im in body length, 44 and 55 um in breadth, 28 and 30 nm diameter of aperture. Although this species is similar in size to D. glans Penard, 1902 (see p. 7), it is distinct in having a transparent, fragile shell, wide aperture and a patterned organic cement. Difflugia mica Frenzel, 1892 DESCRIPTION. The shell is brown, spherical or ovoid with a shallow apertural collar (Fig. DIFFLUGIA IN BRITAIN 51 Fig. 33 Difjlugia masaruzii: a, lateral view x 1400; b, apertural view x 1 100; c, shell surface illustrating the distribution of organic cement x4200; d, detail of organic cement network x 26 000. 34a). It is composed of small flattish pieces of quartz (Fig. 34d), packed tightly together to form a strong structure with a smooth surface and positive outline. Only small strands of organic cement are visible between the particles (Fig. 34e). The aperture is circular and usually well defined by the collar, which has a thin, even layer of organic cement around it 52 C. G. OGDEN Fig. 34 Difjlugia mica: a, latero-apertural view showing the shallow collar x 1600; b, apertural view, note that the aperture is blocked by a cyst plugx 1 100; c, portion of apertural collar to illustrate the organic cement covering x3900; d, shell surface with close packing of particles x 3800; e, detail of organic cement x 24 000. DIFFLUGIA IN BRITAIN 53 (Figs. 34b & c). The illustrated specimen has a broken cyst membrane, made mainly of organic cement, just inside the apertural opening. MEASUREMENTS, (in um). Based on seven specimens: body length 44-58, breadth 36^9, diameter of aperture 12-1 8; B/L 0-81 ±0-10, d/L 0-31 ±0-05. MATERIAL EXAMINED. Specimens were collected from a sample of aquatic plants taken at the banks of the River Brett, near Hadleigh, Suffolk, in August, 1979. GEOGRAPHICAL DISTRIBUTION. Argentina (Frenzel, 1892), Germany (Schonborn, 1962a & b, 1965), Poland (Moraczewski, 1961, 1965); Roumania (Godeanu et al., 1973), Switzerland (Penard, 1902). REMARKS. This species was initially described as Difflugia sp. by Frenzel (1892), the specific name being added as a footnote (p. 135). In redescribing the species Penard (1902) used the name D. mica? Frenzel, the query has been dropped by subsequent authors and the name considered to be valid. Difflugia microstoma (Thomas, 1954) comb. nov. Difflugia globularis var. microstoma Thomas, 1954 DESCRIPTION. The shell is ovoid or subspherical, composed mainly of a mixture of small to medium pieces of flattish quartz and diatom frustules. The particles are arranged to give a relatively smooth outline (Fig. 35a), with the diatom frustules being in general additions to the main structure (Fig. 35d). The close packing of materials is such that only small strands of organic cement are seen (Fig. 35c). The aperture is circular and usually surrounded by a border of small particles (Figs. 35b & e). MEASUREMENTS (in um). Based on fifteen specimens: body length 76-105, breadth 63-83, diameter of aperture 1 8-29; B/L 0-79 + 0-07, d/L 0-26 ±0-03. MATERIAL EXAMINED. Specimens were collected from Sphagnum moss gathered at Holmsley Lodge, Burley, New Forest, Hampshire in July, 1978; March, 1980 and at Myndd Hiraethog, Denbigh, Clwyd, North Wales in August, 1980. GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), France (Thomas, 1954). REMARKS. Thomas (1954) considered when describing the variety D. globularis var. microstoma that it was similar to specimens of/), globulosa illustrated by Penard (1902, p. 258 Fig. 6), although he later (Gauthier-Lievre & Thomas, 1958) proposed both as synonyms of D. minuta Rampi, 1950. The examples of D. minuta described in this report show that D. microstoma is distinct in having a larger ovoid shell with a small aperture (compare ratios B/L and d/L, below), the latter feature also differentiates it from D. globulosa Dujardin, 1837. Difflugia minuta Rampi, 1950 DESCRIPTION. The shell is ovoid or spherical, composed mainly of small pieces of flattish quartz and the occasional fragment or diatom frustule (Fig. 36a). The particles are packed so closely, to give a robust structure, that organic cement is visible only as small strands (Fig. 36c). The aperture is small and often surrounded by a narrow lip of organic cement (Fig. 36d), the lip is not apparent in side view but makes the apertural opening distinct when viewed en face (Figs. 36b & d). MEASUREMENTS, (in um). Based on six specimens: body length 44-53, breadth 34-48, diameter of aperture 9-12; B/L 0-98 + 0-08, d/L 0-25 ±0-04. 54 C. G. OGDEN Fig. 35 Difflugia microstoma: a, lateral view of shell with smooth surface x980; b, apertural view x770; c, portion of shell surface with strands of organic cement x 13 000; d, lateral view of shell with added diatom frustules x 770; e, apertural view x 580. DIFFLUGIA IN BRITAIN 55 Fig. 36 DiJJlugia minuta: a, lateral view x 1400; b, apertural view x970; c, portion of shell surface showing close packing of particles x7700; d, detail of aperture to show narrow lip of organic cement x3700. MATERIAL EXAMINED. Specimens were collected from samples of Sphagnum moss gathered at three locations, Cranes Moor, in May, 1977; Holmsley, in July, 1978, both in the New Forest, Hampshire; Myndd Hiraethog, North Wales in August, 1980; and aquatic plants taken at the bank of a pond near Burley, New Forest in March, 1980. GEOGRAPHICAL DISTRIBUTION. Brazil (Green, 1975), Costa Rica (Laminger, 1973a), Germany (Schonborn, 1965), Italy (Rampi, 1950), Roumania (Godeanu £/ a/., 1973). REMARKS. The initial report (Rampi, 1950) of this species is brief, consisting of one figure and a few lines of description. These note that it has a globular shell made mainly of quartz particles and concludes that it differs from D. globulosa by its small size, length 53 um, breadth 48 urn. Unfortunately no dimensions for the aperture are given. The specimens referred to this species by Gauthier-Lievre & Thomas (1958) are all much larger than the measurements given by Rampi (1950), and are here considered to represent D. microstoma (see p. 53). D. minuta is considered a distinct species in having a circular shell composed mainly of quartz, with a small aperture surrounded by a narrow lip or rim of organic cement. 56 C. G. OGDEN Fig. 37 Difflugia rotunda: a, apertural view x270; b, lateral view x240; c, apertural view of specimen made mainly of quartz particles, note the regular outline of the aperture x290; d, portion of shell surface of 'diatom' specimen x 3300; e, shell surface of specimen made mainly of quartz x 2900. Difflugia rotunda nom. nov. Difflugia globularis var. sphaerica Chardez, 1956 DESCRIPTION. The shell is brownish, spherical or hemispherical, with the outline frequently distorted by the addition of large diatom frustules (Figs. 37a & b). The basic structure is made DIFFLUGIA IN BRITAIN 57 mainly of quartz (Fig. 37c), but diatom frustules or fragments of frustules, are often mixed with this in different proportions (Fig. 37b). This material is usually packed tightly together so that only small strands of cement are seen (Figs. 37d & e). The aperture is circular, sometimes slightly irregular, but usually surrounded by a shallow rim of small particles (Figs. 37a&c). MEASUREMENTS (in um). Based on sixteen specimens: body length 133-204, breadth 138-193, diameter of aperture 79-1 13; B/L 0-98 + 0-12, d/LO-55±0-07. MATERIAL EXAMINED. Specimens were collected from samples of Sphagnum moss gathered at Holmsley Lodge, Burley, New Forest, Hampshire in May, 1978; March, 1979; 1980 and Myndd Hiraethog, Denbigh, Clwyd, North Wales in August, 1980. GEOGRAPHICAL DISTRIBUTION. Argentina (Vucetich, \913a & b), Belgium (Chardez, 1956). REMARKS. In the original description of this variety, D. globularis var. sphaerica, Chardez (1956) noted that it differed in both size and diameter of aperture, the latter feature being about half the breadth, from his concept of/), globularis. According to Cash & Hopkinson (1909) the name globularis was used in error by Wallich (1864) for D. globulosa Dujardin, 1837. Nevertheless, these distinguishing features are used here to differentiate these specimens from other spherical species. Again a new name is proposed because the term sphaerica has been widely used for varieties in the terminology of this genus. ETYMOLOGY. The specific name has been chosen to reflect the shape of the shell (L. rotunda — round circular or orbicular). Difflugia stoutii sp. nov. DESCRIPTION. The shell is ovoid or ovoid elongate, composed of mainly small, flattish particles of siliceous material, including quartz, diatom frustules and shell plates from smaller testate amoebae (Figs. 38a & d). It is extremely fragile, several specimens having collapsed in preparation, and hence the apparent lateral flattening of the specimen shown in Fig. 38c. Organic cement is seen only as small threads due to the regular overlapping of the shell components (Fig. 38e). The aperture is roughly circular, small and appears to be recessed, but this latter feature may be due to structural fragility (Figs. 38b & d). MEASUREMENTS (in um). Based on four specimens: body length 47-59, breadth 33-36, diameter of aperture 9-12. MATERIAL EXAMINED. Specimens were collected from a sample of Sphagnum moss gathered at Myndd Hiraethog, Denbigh, Clwyd, North Wales in August, 1979. REMARKS. The present specimens are similar to three species recently described from Germany, namely D. stechtinensis Schonborn, 1962, D. sudiformis Schonborn, 1966 and D. szczepanskii Schonborn, 1965. They differ from the two former species in general dimensions, D. stechtinensis is almost spherical, with an aperturual diameter equal to half the body breadth, whilst D. sudiformis is an elongate, very slender species. D. szczepanskii is a slightly larger species but differs mainly in having an aperture size two-thirds of the body width. All three species are described as having a hyaline shell covered with a meagre scattering of particles. D. stoutii is distinct in having a fragile, elongate ovoid shell composed of flattish particles and a small aperture. ETYMOLOGY. This species is named after the late Dr John Stout in recognition of his contributions to recent advances in protozoology. Difflugia urceolata Carter, 1864 DESCRIPTION. The shell is opaque, ovoid or rotund, often having one or more irregular blunt 58 C. G. OGDEN Fig. 38 Difflugia stoutii: a, lateral view x 1 700; b, apertural view x 1 700; c, lateral view ot" specimen slightly compressed anteriorly x 1 100; d, latero-apertural view of ovoid specimen with slightly recessed aperture x 1 300; e, shell surface, note the overlapping of particles x 5800. DIFFLUGIA IN BRITAIN 59 aboral protruberances, and a pronounced apical rim or collar (Fig. 39a). The rim has a recurved appearance the edge of which is usually well denned (Figs. 39b & c), with an abundance of organic cement apparent as part of the rim matrix (Fig. 39e). The body is composed of small to medium particles of quartz, blended together so that the smaller particles and organic cement fill the gaps between the larger particles and give a relatively smooth surface. Diatom frustules or parts of them are occasionally included in the structure. Organic cement in the form of a network is seen as part of the matrix (Fig. 39d), the mesh has a diameter of about 240-290 nm with walls 100-180 nm thick (Fig. 39f). The aperture is usually circular (Fig. 39a). Variation in this species is not uncommon. Although usually limited to the presence or absence of aboral protruberances, an occasional deformed shell may be seen. The specimen illustrated here (Figs. 40a & b) has a depressed apical rim, malformed body and defined aboral protruberances are absent. MEASUREMENTS (in jim). Based on twenty-one specimens: body length 204-398, breadth 193-^26, diameter of aperture 87-198; B/LO-92±0-10,d/L 0-44 + 0-06. MATERIAL EXAMINED. Specimens were collected from samples of Sphagnum moss gathered at Holmsley Lodge, Burley, New Forest, Hampshire on several occasions, May, 1977; 1978 and March, 1980. GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Argentina (Boltovskoy & Lena, 1971, 1974; Dioni, 1970; Vucetich, 19730 & b), Australia (Playfair, 1918), Austria (Laminger, 1972c, 19736), Belgium (Chardez, 1960, 19616; Chardez & Gaspar, 1976), Brazil (Green, 1975), British Isles (Cash & Hopkinson, 1909; Ogden & Hedley, 1980), Chile (Decloitre, 1954), China (Decloitre, 1954), Congo (Chardez, 1964; Stepanek, 1963), Czechoslovakia (Stepanek, 1952), France (Deflandre 1962b; Thomas, 1954), Germany (Jung, 1936), Hungary (Bereczky, 1973), Italy (Grandori & Grandori, 1934), Java (Bartos, 1963a), Netherlands (Hoogenraad & Groot, 1940), Poland (Moraczewski, 1965), Russia (Kourov, 1925), Spain (Margalef, 1955), Sudan (Gauthier- Lievre & Thomas, 1 958), Switzerland (Penard, 1 902), United States of America (Laminger et al, 1979), Venezuela (Deflandre, 19260;Grospietsch, 1975). REMARKS. This is one of the most widely reported specimens ofDifflugia, probably due to its size and distinctive shape. However, variation in shell construction has led to the description of several varieties. Thomas (1954) used the presence of aboral protruberances to differentiate the variety olla Leidy, 1879; whilst Gauthier-Lievre & Thomas (1958) list four which differed in rim construction, namely lageniformis (Wallich), lageniformis forma minor forma nov., minor Deflandre and sphaerica Playfair; and more recently descriptions of specimens which differed in shape and material have produced two more-var. chayuensis Wang Jiagi, 1977 and forma subureceola Chardez & Gaspar, 1976. These reports of natural variation can have little value until they are thoroughly investigated, and the present specimens are therefore referred to D. urceolata. Compressed species Difftugia himethogii sp. nov. DESCRIPTION. The shell is light yellow or transparent, thin pyriform with a distinct neck or collar which often has parallel sides (Figs. 4 la & b). The neck region is made of angular quartz and usually has a rough appearance (Fig. 41b), whilst the remainder of the body is composed of small to medium pieces of flattened quartz and has a smooth appearance. Organic cement is frequently seen in small areas as part of the shell matrix (Fig. 4 Id). It is in the form of a network, made of fused rings each having an internal diameter of about 250-320 nm and walls 200-260 nm thick (Fig. 41e). The aperture is circular and surrounded by assorted particles of quartz to give it an irregular outline (Fig. 41c). 60 C. G. OGDEN Fig. 39 Dijjlugia urceolata: a, apertural view x 180; b, lateral view, note the apertural collar and small aboral protruberances x 260; c, part of apertural collar, note the well-defined edge of small particles x 790; d, portion of shell surface to illustrate the distribution of organic cement x 5600; e, detail of apertural collar shown in c. x 3700; f, detail or organic cement network x 1 5 000. DIFFLUGIA IN BRITAIN 61 Fig. 40 Difflugia urceolata specimen with a deformed shell; a, lateral view x 1 70; b, latero-apertural view x 1 60. Some of the examined specimens had cyst plugs in their apertural openings. These plugs varied from being either an uneven mixture of angular quartz (Fig. 42a) or flattish pieces (Fig. 42b), in both instances the sealing cement was similar to that binding the shell walls (Figs.42c&d). MEASUREMENTS (in jim). Based on twenty-six specimens: body length 137-171, breadth 87-1 37, depth 57-84 diameter of aperture 35-52; B/L 0-67 ±0-06, d/L 0-26 ±0-02. MATERIAL EXAMINED. Specimens were collected from a sample of Sphagnum moss gathered at Myndd Hiraethog, Denbigh, Clwyd, North Wales in August, 1980. REMARKS. This species is similar to two other compressed species namely, D. compresscf! and D. lingula Penard, 1911. Complications regarding the species D. compressa Carter, 1 864 should have been resolved by Cash & Hopkinson (1909) who suggested that from Carter's figures he was 'beyond question' referring to a species of Pontigulasia. Nevertheless, the name has been used subsequently to refer to compressed specimens of Difflugia, either as D. compressa or D. oblonga/pyriformis var compressa. Whether or not there are some genuine specimens of Difflugia amongst these descriptions is difficult to know, but the name compressa is preoccupied by Carter's description and is no longer valid, and most refer to much longer, broader specimens than those described here. The present specimens are distinct from D. lingula Penard, 1911 and D. lingula var regularis Gauthier-Lievre & Thomas, 1958 because these have a more rounded shape which tapers sharply from the mid-body region to the aperture, and D. lingula also has an aboral horn. D. hiraethogii can be recognised by its lateral compression, distinct circular collar and aperture. ETYMOLOGY. This species is named after the area of North Wales in which it was found. Difflugia lucida Penard, 1890 DESCRIPTION. The shell is transparent, ovoid, gracefully curved aborally but tapering more gradually towards the aperture to give a well defined outline (Fig. 43a), and laterally compressed (Fig. 43c). It is thin, smooth and composed mainly of flattish pieces of quartz with an occasional siliceous shell plate or diatom frustule added, these particles are usually arranged so that they meet but do not overlap. Small areas of organic cement, in the form of a network, are seen as part of the shell matrix (Fig. 43d). The network is often an arrangement 62 C. G. OGDEN Fig. 41 Dijjlugia hiraethogii: a, lateral view x 730; b, lateral view to illustrate the distinct circular neck and compressed body x430; c, apertural view x540; d, portion of shell surface showing small areas of organic cement x 3500; e, detail of organic cement x 1 3 000. DIFFLUGIA IN BRITAIN Fig. 42 Difflugia hiraethogii: a, detail of aperture with cyst plug composed mainly of angular quartz, organic cement at edges x 1 500; b, specimen with cyst plug composed mainly of organic cement x 1100; c, portion of cyst plug shown in b., note that the particles appear to be well embedded in organic cement x 3500; d, detail of organic cement of cyst plug x 1 7 000. of rings whose internal diameter is about 38(M80 nm with walls 95-125 nm thick (Fig. 43e). The aperture is elliptical and surrounded by irregularly arranged particles which give a rough outline to the immediate apertural region (Figs. 43a & b). Several presumably encysted specimens were present in the sample, and easily distinguished optically by the dark -appearance around the aperture. On detailed examination this dark area was seen to be a concentration of flat particles projecting from the apertural openings (Figs. 44a & b). MEASUREMENTS (in urn). Based on thirty-six specimens: body length 67-91, breadth 40-55, depth 23-37, diameter of aperture 23-29, depth of aperture 13-19. MATERIAL EXAMINED. Specimens were collected from a sample of Sphagnum gathered at Myndd Hiraethog, Denbigh, Clwyd, North Wales in August, 1980. GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Argentina (Vucetich, 1972), Austria (Laminger, 1972a, 19736, 1974, 1975), Belgium (Chardez, 19616; Couteaux, 1969), British Isles (Cash & Hopkinson, 1909), Bulgaria (Golemansky, 1967), Canary Isles (Gracia, 1965a & b), China (Bartos 19636), Congo (Chardez, 1964; Stepanek, 1963), Costa Rica (Laminger, 1973a), Czechoslovakia (Rosa, 1957; Stepanek, 1952, 1967), 64 C. G. OGDEN Fig. 43 Difflugia lucida: a, lateral view to illustrate basic outline x 1 300; b, apertural view x 1 100; c, view showing lateral compression and smooth surface x 840; d, part of shell surface with small areas of organic cement x 5900; e, detail of organic cement network x 23 000. DIFFLUGIA IN BRITAIN 65 Fig. 44 Difflugia lucida specimen with cyst plug, note the irregular arrangement of particles in the apertural opening: a, lateral view x620; b, apertural view x 1 100. angulostomai \ angulostoma minuta mica \ stout/ i / \ masaruziil \ decloitrei / \ ampullula Fig. 45 Diagrams of ovoid, spherical and compressed species to illustrate the basic outline, based on measurements given in Table 4. Note that D. rotunda and D. urceolata are drawn to the reduced scale. 66 C. G. OGDEN Table 4 Average dimensions of ovoid or spherical species and compressed species used to give basic outlines illustrated in Fig. 45 Species Length Breadth Diameter of aperture angulostoma a. 48 45 20 b. 68 58 38 minuta 45 44 11 mica 51 41 16 stoutii 53 34 11 masaruzii 66 41 25 decloitrei 79 45 24 ampululla 77 59 25 microstoma 91 72 23 rotunda 165 159 90 urceolata 314 283 143 lucida hiraethogii length 76 150 breadth depth 46 104 30 67 diameter of aperture 17x25 41 France (Thomas, 1954), Germany (Schonborn, 19620 & b\ Guatemala (Laminger, 19730), Hungary (Varga, 1963), Italy (Grandori & Grandori, 1943; Rampi, 1950), Java (Bartos, 19630; Hoogenraad & Groot, 19406), Mexico (Laminger, 19730), Morocco (Decloitre, 1961), Nepal (Laminger, 19726), Netherlands (Hoogenraad & Groot, 19400), Poland (Golemansky, 1970; Pateff, 1926), South Shetland Isles (Smith, 1972), Spain (Gracia, 1964), Switzerland (Penard, 1902). REMARKS. Some differences in dimensions are worth noting from earlier descriptions; Penard (1 890) gave a range of body length 50-70 um, but later stated that specimens ranged between 50-60 and rarely greater than 65 um (Penard, 1902), Cash & Hopkinson quoted 60-80 um, whilst Gauthier-Lievre & Thomas (1958) suggested that there might be three groups (a) 44-50 (b) 55-70 (c) 83-90. In the present group of specimens only seven are outside of the range 70-80 um and they are remarkable for their similarity. This species is distinct in having a well defined shape and by being evenly compressed. Discussion One of the main difficulties encountered in trying to identify specimens ofDifflugia is due to the irregular shape of the shell. It is a problem shared with other agglutinate species of protozoa, such as the foraminifera. In general most species have a regular basic outline, which may be altered by either natural variation or obscured by the addition of extraneous material. Both natural and additional variation are probably related to the composition of the shell, fragile shells being more likely to be influenced by disturbances in the environment during or after construction, whilst robust shells may be so encrusted by particles that any resemblance of a specific shape is lost. Fragile shells are usually made of small particles arranged in a single layer and often have organic cement as a major component of the shell matrix. In some species a smooth surface composed of flattish particles is constructed, for example D. mamillaris, where variation in DIFFLUGIA IN BRITAIN 67 general shape is frequently seen especially in the aboral region (see Fig. 23). Nevertheless, in a species with a similar surface but different shape, D. lanceolata which is rounded rather than pointed in the aboral region, there is a relatively constant shape. In the present report a third of the specimens of D. mamillaris differ from the basic outline given in Fig. 29, whilst all of the specimens of D. lanceolata agree with the outline in Fig. 1 8. Although robust shells are usually made of angular quartz which do not lend themselves to being arranged in a regular manner, if enough specimens of a species is present in a sample it is possible to illustrate a basic outline. The problems of subsequent recognition of such species from the basic outline is complicated when the diagnostic feature is obscured by the arrangement of particles. For instance the diagnostic feature may be the presence of a neck, but if this is hidden it may be identified incorrectly. Amongst species with this type of shell, examples of specimens incorporating a single large particle with similar dimensions to the whole shell have been observed and a not infrequent sight is to see two similar shells united. In these latter instances the shell is usually of similar size and composition, but these are not necessarily species of Difflugia but can be other agglutinate forms like Pontigulasia (pers. observation). To assist in resolving the question of what represents the basic outline in the species described here, three sets of line drawings are provided (Figs. 18, 29, 45) which are based on the average dimensions of the specimens examined. In the previous studies on pyriform species of Difflugia it has been suggested (Ogden, 1979) that measurements are useful in distinguishing species, with the body length and diameter of aperture perhaps being the more stable dimensions. However, it was emphasised that these features alone are not usually sufficient to warrant specific diagnoses. The problem of using dimensions as a diagnostic character is that they may be valid for a proportion of species in a genus, but do not hold for all especially in the present instance with a genus supposedly comprised of over three hundred species. Possibly this is best illustrated by the variability in size exhibited within a species of testate amoebae, the smallest often being reported as half the size of the largest, which does not pose problems of identification when the body length is under 80 um, but for those of larger dimensions the difference between 200 jim and 400 urn can often be interpreted as representing two separate species. The extreme example is as we have noted previously (Ogden & Fairman, 1979) the range of measurements quoted for the body length of D. oblonga, 60-580 um, which is so variable that it could embrace most of the genus or almost all of the described testate amoebae. Nevertheless, there are examples of consistent dimensions within a species, for instance those of D. lanceolata and D. mamillaris described here are in good agreement with previously published results (Penard, 1902; Grospietsch, 1957). The regularity of body length in D. lanceolata is such that over 87% of the specimens fall within a range of ± 10% of the average value given in Table 2, whilst in D. mamillaris 96% fall within the same range. Ovoid or spherical specimens of Difflugia present the same problem. In certain cases groups of similar species may only be distinguished by dimensions, for example D. anchlora, D. gramen and D. lobostoma (see Ogden, 1980) which may represent a phylogenetic series. Whilst is other cases, like the D. globulosa/globularis species complex, size variation is so great that it is difficult not to include any ovoid or spherical specimen between 50-1 50 um in this complex. Part of the difficulty is illustrated by the two groups of specimens described here as D. angulostoma (p. 47), where the shells are identical in construction and essentially they share the same shape, but there are differences in dimensions especially the diameter of the aperture. It is possible to separate some of these small spherical species using the latter feature in addition to other differences, as shown in the descriptions of D. minuta, D. mica and D. microstoma (see p. 53, p. 50 & p. 53). Structural differences in basic outline as mentioned earlier are mainly related to shell components and deformities, the former concerns the choice of materials and will be dealt with later, but the latter using D. urceolata as an example may be due to its large size. Perhaps it is easier to understand if one considers that in all probability the shell components are not cemented together until the final shape 68 C. G. OGDEN has been moulded by cytoplasmic movements. As this process takes about sixty minutes in a small siliceous species (Ogden, 1981), it will probably take considerably longer in a larger animal, during which time in a natural environment there is a continual motion and hence a possibility of disruption. The result of such a disturbance may produce the shell illustrated in Fig. 40, sufficiently different from normal but not enough for the animal to abhort and discard the shell prior to the final stiffening of the cement. Studies on clonal cultures of both siliceous and proteinaceous species (Ogden, 1981 & pers. observations) show that variation in dimensions are small, differences outside the norm usually being attributed to abnormal development and even here it is usually below 5%. Such abnormal development is thought to be associated with cultural differences and not a frequent natural occurrence. One feature of siliceous species behaviour which may explain some changes in dimensions, is the occasional production of a shell having a double complement of shell plates (Hedley & Ogden, 1973). However, this results in an increase in volume of an ovoid structure, which means that the enlargement in body length is probably no greater than a third. At present there are only two reports (Jennings, 1916, 1937) on the development of Difflugila corona in the laboratory. Both have shown that there can be some variation in shell construction and until further observations are available on other species of Difflugia, the question of shell size and composition as diagnostic features will remain a subject of speculation. Mention has already been made in the literature of differences in shell construction and the three categories which are readily identified, robust, intermediate and fragile (Ogden, 1980). But the choice of materials, other than a comment (Ogden, 1980) on the influence of pH, has not been discussed. That a system of choice is available to the animal is clearly demonstrated by the composition of certain shells. For example, D. minutissima, D. lanceolata, D. mamillaris and D. decloitrei all use flattish pieces of quartz, in some instances small flat particles of diatom frustules may be substituted, but the components used appear to be restricted in size and thickness. The function of the cytoplasm to identify and select these particles may appear to be extreme. Nevertheless, it can be measured against the ability of siliceous testate amoebae to hold each shell plate during shell construction, place it in position so that there is an even amount of overlap between plates and in some specimens manipulate spines into definite positions (Ogden, 1981). This selectivity is not restricted to flat particles, but probably includes the choice of diatoms or angular particles, as well as mixtures of all types in the composition of Difflugia shells. An additional factor that influences the choice of particles is undoubtedly the structure and extent of organic cement in the shell matrix. It has already been suggested (Ekert & McGee-Russell, 1974) that the organic cement which binds the shell particles together in Difflugia lobostoma imparts both strength and flexibility to the structure. This may seem obvious from the different type of shells constructed by these animals, but it has an importance related to the material used. For instance, when the cement becomes part of the surface matrix, usually in species with flat particles, it is found at each facet as part of the shell wall. The strength of the shell is then directly related to the tenacity of the cement at these junctions. Furthermore, in species where there is some overlapping of particles the cement is interwoven with the material and can be likened to the structure of a brick wall, in which the strength is dramatically increased by the combination of bricks and mortar beyond the strength of the individual materials assessed on their own. The importance of the organic cement in shell structure is easily demonstrated by treating a robust individual with either a chelating agent or concentrated sulphuric acid, in each case within a short time it is reduced to a small residue of particles. Strength is not directly due to the composition of the acid mucopolysaccharide material that forms the basic organic cement, but to the properties of this material. It has already been shown that inorganic elements incorporated with this type of material in the proteinaceous shells of testate amoebae (Hedley et al, 1976; pers. observ.) DIFFLUGIA IN BRITAIN 69 and areanceous foraminifera (Hedley, 1963) are thought to strengthen the shell. Some specimens of Difflugia have been examined by X-ray microanalytical techniques (pers. observ.), and found to have a significant amount of ferrous iron associated with areas of organic cement. This probably accounts for the reports of yellow or brown specimens, the degree of colouration being proportional to the amount of inorganic elements bound to the organic cement. There is no doubt that the density of this colouration in proteinaceous specimens can be used as a measure of the degree of reinforcement that the inorganic elements impart to the structure, newly formed shells being light coloured and fragile, whilst older shells are dark and strong. This measure can probably be applied to agglutinate forms as well. The differences in the network structure of the organic cement are harder to understand, especially as the examination is limited to surface detail. A need for porosity in some of the individual organic cement units is puzzling. If they are definite pores to the interior of the shell they might function as pressure valves for aqueous interchange, because often when the animal is moving or feeding the apertural opening is completely blocked by cytoplasmic extrusions. Such a scheme could ensure that the internal volume unoccupied by cytoplasm is not isolated and allowed to stagnate. Alternatively it may be associated with the hardening process by inorganic elements. This process seems to be directly related to the environment and the chemical composition of the cement, the activities of the animal apparently having no effect on this association. The strengthening process has some degree of justification because the pores often seen between individual proteinaceous units is newly-formed, light coloured, shells ofArcella, are not seen in older darker specimens. Examination of the walls of such specimens show that they are thick and stronger, the implication being that the inorganic elements have strengthened the shell not the deposition of further organic material (pers. observ.). The diversity in the construction of the organic cement units is considered to be a good taxonomic feature, although they are beyond the limit of optical microscopy, the appearance of some being particularly unique for example the button-type of D. lacustris (see Fig. 5e p. 9). The sharing of the same type of unit between different species may suggest some phylogenetic relationship, possibly linked to the type of shell construction whether smooth, rough, fragile or strong. However, at present only a quarter of the described species have been examined and it is too early to make proposals on such relationships. That is apart from the apparent sharing of the same organic cement pattern between most ovoid species. It is hoped that further studies in progress on this genus will help to unravel the complications attributed to describing so many different shapes and forms, and allow a comprehensive division based on shell structure. References Awerinzew, S. 1906. Die Strucktur und die chemische Zusammensetzung der Gehause bei den SiiBwasser-rhizopoden. Arch. Protistenk. 8: 95-1 11. Bartos, E. 1963a. Rhizopoden einiger moosproben aus Java. Acta Univ. Carol. 1 19-190 19636. Die Rhizopoden einiger Moosproben aus China. V$stn. csl. Spol. zool. 27: 85-96. Bereczky, M. Cs. 1973. Beitrage zur Kenntnis der im Eprofundal des Balaton lebenden testaceen. Annies Univ. Scient. bpest. Rolando Eotvos (Sect. Biol.) 15: 1 17-127. Blanc, H. 1892. Les Difflugies de la faune profonde du Lac Leman. Recuiel inaugural de 1'Umversite de Lausanne 8°. Lausanne. Carter, H. J. 1864. On Freshwater Rhizopoda of England and India; with illustrations. Ann. Mag. nat. Hist. (3)13: 18-39. Cash, J. & Hopkinson, J. 1909. The British Freshwater Rhizopoda and Hehozoa. Vol. II Rhizopoda, part 2. 166 pp. The Ray Society, London. Cash, J., Wailes, G. H. & Hopkinson, J. 1919. The British Freshwater Rhizopoda and Hehzoa. Vol. IV. Supplement to the Rhizopoda. 1 30pp. The Ray Society, London. 70 C. G. OGDEN Chardez, D. 1956. Thecamoebiens de la region Vervietoise. Revue verviet. Hist. nat. 13 (3-4): 23-32. - 1 960. Etudes sur deux Difjlugia. Hydrobiologia 16: 1 1 8-125. - 196 la. Sur Difjlugia acuminata Ehrenberg (Rhizopoda, Testacea). Bull. Inst. agron. Stns Rech. 19616. Catalogue des Thecamoebiens de Belgique. Protozoa, Rhizopoda, Testacea. Bull. Inst. agron. Stns. Rech. Gembloux 29: 269-300. 1964. Thecamoebiens (Rhizopoda, Testacea). Expl. hydrobiol. L. Bangweolo-Luapula 10 (2); 1-77. 1973. Sur Dijjlugia ventricosa Deflandre, 1926 (Rhizopoda, Thecamoebien). Revue verviet. Hist. nat. 30 (7-9): 57-60. -. 1980. Thecamoebiens de 1'Etang de Thommen (Protozoa, Rhizopoda, testacea). Naturalistes belg. 61: 88-91. Chardez, D. & Caspar, Ch. 1976. Thecamoebiens aquatiques du domaine des Epioux (Ardenne, Belgique). Biol. Jaarb. 44: 86-100. Couteaux, M. M. 1969. Thecamoebiens muscicoles de Gaume et de Moyenne-Belgique. Revue Ecol. Biol. SV>/.60:413-428. Decloitre, L. 1947. Rhizopodes de la Station de Tanaf. Feuille Nat. 2: 91-94. 1948. Materiaux pour une faune rhizopodique d'A.O.F. Bull. Inst.fr. Afr. noire 10: 235-285. 1961. Materiaux pour une faune thecamoebien du Maroc: 2e note. Thecamoebiens des sols aeriens des palmiers de Marrakech. Bull. Soc. Sci. nat. Maroc 41: 121-1 36. 1965. Contribution a la faune du Congo (Brazzaville) Mission A. Descarpentardes et A. Villiers. Ill Rhizopodes, Thecamoebiens. Bull. Inst.fr. Afr. noire 27 A: 165-184. Deflandre, G. 1926a. Notes sur quelques Rhizopodes et Heliozoaires du Venezuela. Bull. Soc. zool. Fr. 51: 5 15-530. 19266. Materiaux pour la faune rhizopodique de France. Rhizopodes du Confolentais. Feuille Nat. 33: 169-170. 193 1 . Thecamoebiens nouveaux ou peu connus 1 . Annls. Protist. 3: 81-95. Dioni, W. 1 970. Taxocenos de tecamebianos en cuencas islenas del Parana Medio 1 . Acta zool. lilloana 27:201-240. Eckert, B. S. & McGee-Russell, S. M. 1974. Shell structure in Difjlugia lobostoma observed by scanning and transmission electron microscopy. Tissue Cell 6: 2 1 5-22 1 . Ehrenberg, C. G. 1938. Die Infusionsthierchen als vollkommene Organismen. Bin Blick in das tiefere organische Leben der Natur. 547 S. Folio, Leipzig. 1854. Mikrogeologie. Fol. Leipzig. 1872. Uebersichte der seit 1847 fortgestzten Untersuchungen iiber das in der Atmosphare unsichtbar getragene reiche organische Leben. Phys. Math. Abh. K. Acad. Wiss Berlin (1 87 1 ): 1-1 50. Ertl, M. 1965. Zur Kenntnis der Testaceenfauna der slowakischen Reisfelder. Hydrobiologia 26: 13-20. Frenzel, J. 1892. Untersuchungen iiber die mikroskopische Fauna Argentiniens. I. Die Protozoen. I & II Die Rhizopoden und Helioamoeben. Biblthca. zool. Stuttgart 12, 162pp Xpl. Gal, D. 1969. Zoolplanktonuntersuchungen im Ostlichen-Hauptkanal. Acta biol. SzegedlS: 93-100. Gassowsky, G. N. 1936. Quelques rhizopodes nouveau des lacs du groupe de Kontchesero (En Karelie). Trudy p res nov. biol. Sta. S-petreb. Obshch Estest. 8 (2): 101-121. Gauthier-Lievre, L. & Thomas R. 1958. Les genres Dijjlugia, Pentagonia, Maghrebia et Hoogenraadia (Rhizopodes, testaces) en Afrique. Arch. Protistenk. 103: 241-370. Godeanu, S. 1972. Especes nouvelles de thecamoebiens (Protozoa, Rhizopoda, Arcellinida). Revue roum. Biol. (Ser. Zool.) 17: 227-236. Godeanu, S., Godeanu, M. & lonescu, V. 1973. Varia^a anualS a planctonului din incintS indiguita Obretin (Delta Dunarii). Peuce3: 21 1-260. Golemansky, V. 1967. Etudes de la faune de Rhizopodes (Sarcodina, Rhizopoda) des mousses epiphytes et terricoles en Bulgarie. Izv. zool. Inst. Sof 24: 103-1 19. 1970. A list of Testacea (Protozoa, Rhizopoda) from the Duszatyriskie Lakes in Poland. Fragm. faun. 16: 21-25. Gracia, M. P. 1964. Tecamebas muscfcoles del valle de Ribas (Gerona). Publnes Inst. Biol. apl. Barcelona 37: 67-71. 1965a. Tecamebas muscicoles de Tenerife. Publnes Inst. Biol. apl. Barcelona 39: 123-127. 19656. Tecamebas muscfcoles de Gran Canaria. Publnes Inst. Biol. apl. Barcelona 38: 93-96. 1972a. Tecamebas esfagnicolas de la Peninsula Iberica. Publnes Inst. Biol. apl. Barcelona 52: 5^2. DIFFLUGIA IN BRITAIN 71 19726. Tecamebas musicolasde la Peninsula Iberica. Publnes Inst. Biol. apl. Barcelona 53: 5-16. Grandori, R. & Grandori, E. 1934. Prime richerche sui Protozoi del terreni e delle acque dell'alta Montagna Alpina. Boll. Lab. Zool. agr. Bachic. R. 1st. sup. agr. Milano 5: 1-340. Green, J. 1975. Freshwater ecology in the Mato Grosso, Central Brazil, IV: Associations of testate Rhizopoda. J. nat. Hist. 9: 545-560. Grospietsch, T. 1957. Beitrag zur Rhizopodenfauna des Lago Maggiore. Arch. f. Hydrobiol. 53: 323-331. 1958. Beitrage zur Rhizopodenfauna Deutschlands I. Die Thekamoben der Rhon. Hydrobiologia 10: 305-322. 1975. Beitrag zur Kenntnis der Testaceen-Fauna des Lago Valencia (Venezuela). Verh. Internal Verein. Limnol. 19: 2778-2784. Hedley, R. H. 1963. Cement and iron in the arenaceous foraminifera. Micropaleontology9: 433-441. Hedley, R. H., Ogden, C. G. & Mordan, N. J. 1976. Manganese in the shell of Centropyxis (Rhizopodea: Protozoa). Cell Tiss. Res. 171: 543-549. Hoogenraad, H. R. & Groot, A. A. de. 19400. Fauna van Nederland Vol. 9. Zoetwaterrhizopoden en Heliozoen. 302pp Leiden. 19406. Moosbewohnende thekamoebae rhizopoden von Java und Sumatra. Treubia 17: 209-259. Jennings, H. S. 1916. Heredity, variation and the results of selection in the uniparental reproduction of Difflugia corona. Genetics 1: 407-534. 1937. Formation, inheritance and variation of the teeth in Difflugia corona. A study of the morphogenetic activities of rhizopod protoplasm. /. exp. Zool. 77: 287-336. Jung, W. 1936. Thekamoben urspriinglicher, lebender deutscher Hochmore. Abh. Landesmus. Prov. 1942. Siidchilenische Thekamoben (Aus dem siidchilensichen Kiistengebiet, Beitrag 10). Arch. Protistenk. 95: 253-356. Kourov, O. 1 925. Faune rhizopodique des bassins de Kossino. Trudy kosin. biol. Sta. 2: 43-68. Laminger, H. 1971. Sedimentbewohnende Schalenamoben (Rhizopoda, Testacea) der Finstertaler Seen (Tirol). Arch Hydriobiol. 69: 106-140. . 19720. Terrestrische Testaceen (Protozoa, Rhizopoda) in der Umgebung von Obergurgl (Osterrich, Tirol). Pedobiologia 12: 16-22. 19726. Notes on some terrestrial Testacea (Protozoa, Rhizopoda) from Nepal, Himalaya (Lhotose Shar). Arch. Protistenk. 114: 486^88. 1972c. Die profundale Testaceeenfauna (Protozoa, Rhizopoda) alterer und jiingerer Bodensee-Sedimente. Arch. Hydrobiol. 70: 108-129. 19730. Die Testaceen (Protozoa, Rhizopoda) einiger Hochgebirgsgewasser von Mexiko, Costa Rica und Guatemala. Int. Revue ges. Hydrobiol. 58: 273-305. 19736. Zur Kenntnis der Testaceenfauna in den jungsten Sedimenten des Bodenseeprofundals und-litorals. Schweiz. Z Hydrol. 35: 239-246. 1974. Ein Beitrag zur Kenntnis der Protozoenfauna der Donau. 1. Die Testaceen (Protozoa, Rhizopoda) im Abschnitt Obernzell-Linz (Oberosterreich). Arch. Hydrobiol. Suppl. 44 3: 330-337. 1975. Die Sukzession der Testaceen- Assoziationen (Protozoa, Rhizopoda) im rezenten und subfossilen Sphagnum des Obersees bei Lunz (Neiderosterreich). Hydrobiologia 46: 465^87. Laminger, H., Zisette, R. Phillips, S. & Breidigam, F. 1979. Contribution to the knowledge of the protozoan fauna of Montane (USA): 1. Testate amoebae (Rhizopods) in the surrounding of Flathead Lake valley. Hydrobiologia 65: 257-27 1 . Leidy, J. 1 874. Notes on some New Fresh-water Rhizopods. Proc. Acad. nat. Sci. Philad. 77-79. 1879. Freshwater Rhizopods of North America in Vol. 12. United States Geological Survey of the Territories. 324pp. Washington. Levander, K. M. 1894. Materialien zur Kenntniss der Wasserfauna in der Umgebung von Helsmgtors, mit besonderer berucksichtigung der Meeresfauna. I. Protozoa. Acta Soc. Fauna Flora Fenn. 12 No. Margalef, R.I 955. Contribution al estudio de la fauna de las aguas dulces del norveste de Espana. Publnes Inst. Biol. apl. Barcelona 21:137-171. Moraczewski, J. 1961. Testacea du littoral peu profond du lac Kisajno (Region des lacs de Mazune). Polskie Archwm. Hydrobiol. 9: 175-194. 1965. Taxocenses des Testacea de quelques petit bassins de terrains mondables de la Narew. Acta Protozool.3: 189-213. 72 C. G. OGDEN Ogden, C. G. 19790. Comparitive morphology of some pyriform species of Difflugia (Rhizopoda). Arch. Protistenk. 122: 143-153. 1979ft. Siliceous structures secreted by members of the subclass Lobosia (Rhizopodea, Protozoa). Bull. Br. Mm. nat. Hist. (Zool.)36: 203-207. 1980a. Shell structure in some pyriform species of Dijjlugia (Rhizopodea). Arch. Protistenk. 123: 455-470. 1980ft. Notes on some Difflugiidae from Norfolk (Rhizopodea, Protozoa). Bull. Br. Mus. nat. Hist. (Zool) 39: 125-1 38. 1981. Observations on clonal cultures of Euglyphidae (Rhizopoda, Protozoa). Bull. Br. Mus. nat. Hist. (Zool.) 41: 137-151. Ogden, C. G. & Fairman, S. 1979. Further observations on pyriform species of Dijjlugia (Rhizopoda). Arch Protistenk. 122: 372-381. Ogden, C.G. & Hedley, R. H. 1980. An Atlas of Freshwater Testate Amoebae. British Museum (Nat. Hist.), London & Oxford University Press, Oxford 222pp. Opravilova, V. 1974. Testacea (Protozoa: Rhizopoda) of the river Bobrava in Moravia. Vestnik csl. Spol. zool. 38: 127-147. Oye, P. van 193 1 . Rhizopoda from South Africa. Rev. Zool. hot. afr. 21: 54-73. 1953. Faune Rhizopodique de Petang de Beernem. Biol. Jaarb. 20: 1 54-205. 1958, Etude sur les rhizopodes des marais du Sud-ouest d'Uvira (Congo-Beige). Hydrobiologia 10: 85-137. Pashitnowa, Z. A. 1929. Materialen zur Erforschung der Mikrofauna der Reisfelder und die Biologic der Anopheles-larvae auf den Reisfeldern. Acta Univ. Asiae mediae Ser. Villa 10: 1-42. Pateff, P. 1926. Siisswasser-Rhizopoden aus der Hohle Salzlocher (Schlesien). Mitt, Hohlen-u Karstforsch. 2: 46-49. 1927. Die von Romer und Schaudinn im Reliktensee Mogilnoje gesammelten Siisswasserrhizqpoden. Zool. Anz. 70: 36-38. Penard, E. 1 890. Etudes sur les Rhizopodes d'eau douce. Mem. Soc. Phys. Hist. nat. Geneve 31 : 1-230. 1893. Pelomyxa palustris et quelques autres organismes inferieures. Archs. Sci. phys. nat. 29: 165-182. 1 899. Les Rhizopodes de Faune profunde dans le lac Leman. Revue suisse Zool. 1: 1-142. 1901 . Notes complementaires sur les Rhizopodes du Leman. Revue suisse Zool. 9: 225-241 . 1 902. Faune Rhizopodique du Bassin du Leman. Geneva 700pp. 1904. Quelques nouveaux Rhizopodes d'eau douce. Arch. Protistenk 3: 391-422. 1 905. Les Sarcodines des Grands Lacs. Libraire de 1'Institut, Geneve 1 33pp. 1911. Rhizopode d-eaux douce. Brit. Antarct. Exped. 1907-1909. Reports on Scient. Investig. vol.1. Playfair, G. J. 1918. Rhizopods of Sidney and Lismore. Proc. Linn. Soc. N.S. W. 42: 633-675. Rampi, L. 1950. Su alcuni Laghetti Alpini del Massiccio dell'Asbisso (Alpi Marittime). Boll. Pesca Pisci. Idrobiol. 26: 207-224. Rosa, K. 1957. Bodenmikrofauna undmikrofauna im Fichtenbestande am PradSd (Altoater). Prirodov. Sb. ostrav. Kraje 18: 7-75. Rosa, K. & Lhotsky, O. 1971. Edaphische Algen und Protozoen im Isergebirge Tschechoslowakei. 0/A:0s22:21-29. Schonborn, W. 1962. Die Okologie der Testaceen im oligotrophen See, dargestellt am Biespiel des GroBen Stechlinsees. Limnologica 1: 1 1 1-182. 1965. The sediment-inhabiting Testacea from some Masurian Lakes. Acta. Protzool. 3: 297-309. 1966. Untersuchungen iiber die Testaceen Schwedisch-Lapplands. Ein Beitragzur Systematik und Okologie der beschalten Rhizopoden. Limnologica 4: 5 1 7-559. Smith, H. G. 1972. The terrestrial protozoa of Elephant Island, South Shetland Islands. Bull. Br. Antarct. Surv. 31: 55-62. Stepanek, M. 1952. Testacea of the pond of Hradek at Kunratice (Prague). Sb. nar. mus. PrazeSE (3): 1-55. 1963. Die Rhizopoden aus Katanga (Kongo-Afrika). Annls Mus. r. Afr. cent. 117: 9-91 . 1967. Testacea des Benthos der Talspere Vranov am Thayafluss. Hydrobiologia 29: 1-66. Thomas, R. 1953. Sur deux formes critiques du genre Dijjlugia Leclerc. Bull. Soc. zool. Fr. 78: 132-136. 1954. Thecamoebiens de la region Bordelaise. Bull. Soc. Hist. nat. TolouseS9: 245-264. Thomas, R. & Mabille, J. 1956. Rhizopodes thecamoebiens observes dans le Department de 1'Aisne. Cah. Nat. 12: 26-32. DIFFLUGIA IN BRITAIN 73 Varga, L. 1 963. Weitere Untersuchungen iiber die aquatile Microfauna der Baradla-Hohle bei Aggtelek (Ungarn). (Biospeologia Hungarica, XVIII). Acta Zool. hung. 9: 439-458. Voeltz-Hohn, J. 1971. Ein Beitrag zur Testaceenfauna (Protozoa, Rhizopoda) des Hochmoores im Naturpark "Hoher Vogelsberg". Philippa 1: 80-84. Vucetich, M. C. 1970. Algunos tecamebianos de la provincia de Formosa. Neotropica 16: 42-48. 1972. Tres nuevas tecamebas muscicoles para la Argentina (Rhizopoda Testacea). Neotropica 18: 126-128. 1973a. Tecamebas muscicoles de la selva marginal de punta lara (Provincia de Buenos Aires, Argentina). Physis (B) 32: 6 1-66. 1973&. Estudio de tecamebianos Argentinos, en especial los del Dominio Pampasico. Revta. Mus. La Plata (Zool.) 11: 287-322. 1978. Neuvos aportes al conocimiento de los tecamebianos del Dominio Subtropical. Neotropica 24: 79-90. Wailes, G. H. 1912. Freshwater Rhizopoda and Helizoa from the States of New York, New Jersey and Georgia, U.S.A.; with supplemental note on Seychelles species. J. Linn. Soc. 32: 121-161 . Wallich, G. C. 1864. On the extent, and some of the principal causes, of structural variation among the Difflugian Rhizopods. Ann. Mag. nat. Hist. (3) 13: 215-245. Wang Jiaji 1977. Protozoa from some districts of Tibetan Plateau. Acta zool. sin. 23: 131-160. Manuscript accepted for publication 4 June 1982 Index of species and synonyms Difflugia acuminata inflata Penard, 1 899 30 amp hora Leidy, 1879 33 amphoralis Cash & Hopkinson, 1909 27 ampullula Playfair, 1918 45 angulostoma Gauthier-Lievre & Thomas, 1958 47 bicruris Gauthier-Lievre & Thomas, 1958 30 bryophila (Penard, 1902) 2 cylindrus (Thomas, 1953) 5 decloitrei Godeanu, 1972 47 distenda nom. nov. 30 elegans tricornis Jung, 1 936 38 gassowskii nom. nov. 5 glans Penard, 1902 globularis microstoma Thomas, 1 954 53 globularis sphaerica Chardez, 1956 56 gramen Penard, 1902 50 hiraethogii sp. nov. 59 labiosa Wailes, 1919 33 lacustris (Penard, 1899) 9 lanceolata Penard, 1 890 1 1 lemanii Blanc, 1892 26 levanderi Playfair, 1918 47 linearis (Penard, 1890) 11 longicollis(Gasso\vsky, 1936) 5 lucida Penard, 1 890 61 mamillaris Penard, 1893 35 manicata Penard, 1902 16 masaruzziOye, 1958 50 mica Frenzel, 1 892 50 microclaviformis(Kourov, 1925) 35 microstoma (Thomas, 1954) 53 minuta Rampi, 1950 53 Difflugia minuta minor Godeanu, 1972 22 minutissima Penard, 1904 16 molesta Penard, 1902 38 oblonga bryophila Penard, 1 902 2 oblonga cylindrus Thomas, 1953 5 oblonga elongata Oye, 1953 17 oblonga lacustris Cash & Hopkinson, 1909 9 oblonga linearis Penard, 1 890 1 1 oblonga microclaviformis Kourov, 1925 35 oblonga parva Thomas, 1 954 1 7 oblonga tenuis Wailes & Penard, 1911 24 oblonga venusta Cash & Hopkinson, 1909 41 parva (Thomas, 1954) 17 paulii nom. nov. 1 7 petricola Cash, 1909 20 pristis Penard, 1902 20 pulex Penard, 1902 pyriformis bryophila Penard, 1 902 2 pyriformis lacustris Penard, 1 899 9 pyriformis longicollis Gassowsky, 1936 pyriformis tenuis Penard, 1 890 24 pyriformis venusta Penard, 1902 41 rotunda nom. nov. 56 stoutii sp. nov. 57 tenuis (Penard, 1890) tricornis (Jung, 1936) urceolata Carter, 1 864 ventricosa Deflandre, 1 926 4 1 venusta (Penard, 1902) 41 viscidula Penard, 1902 24 Sexangularia minutissima (Penard, 1 904) 1 6 British Museum (Natural History) An Atlas of Freshwater Testate Amoebae C. G. Ogden & R. H. Medley 1980, Hardcovers, 222pp, £17,50 (£18.00 by post). Co-published by British Museum (Natural History) and Oxford University Press. This book illustrates, using scanning electron micrographs, most of the common species of testate amoebae that are found in freshwater habitats. Information on the biology, ecology, geographical distribution and a classification are followed by descriptions of ninety-five species. Each of these is illustrated by several views of the shell. The text is designed not only to enable biologists to identify species of testate amoebae, but to serve as an introduction to students interested in the taxonomy and biology of these freshwater protozoa. It will be of special interest to protozoologists, ecologists, limnologists, water treatment specialists and micropalaeontologists interested in recent sediments. British Museum (Natural History) Publication Sales, Cromwell Road, London SW7 5BD. Titles to be published in Volume 44 Observations on the systematics of the genus Difflugia in Britain (Rhizopoda, Protozoa). By Colin C. Ogden Miscellanea A review of the Euplotidae (Hypotrichida, Ciliophora). By Colin Curds & Irene C. H. Wu Osteology, genitalia and relationships of the Acanthodactylus (Reptilia: Lacertidae). By E. N. Arnold The Opthalmotilapia assemblage of cichlid fishes reconsidered. By Peter Humphrey Greenwood Morphological studies on some Difflugiidae from Yugoslavia (Rhizopoda, Protozoa). By Colin G. Ogden & Andjelija Zivkovic Printed by Henry Ling Ltd, Dorchester Bulletin of the British Museum (Natural History) Miscellanea Zoology series Vol 44 No 2 24 February 1983 The Bulletin of the British Museum (Natural History), instituted in 1949, is issued in four scientific series, Botany, Entomology, Geology (incorporating Mineralogy) and Zoology, and an Historical series. Papers in the Bulletin are primarily the results of research carried out on the unique and ever-growing collections of the Museum, both by the scientific staff of the Museum and by specialists from elsewhere who make use of the Museum's resources. Many of the papers are works of reference that will remain indispensable for years to come. Parts are published at irregular intervals as they become ready, each is complete in itself, available separately, and individually priced. Volumes contain about 300 pages and several volumes may appear within a calendar year. Subscriptions may be placed for one or more of the series on either an Annual or Per Volume basis. Prices vary according to the contents of the individual parts. Orders and enquiries should be sent to: Publications Sales, British Museum (Natural History), Cromwell Road, London SW7 5BD, England. World List abbreviation: Bull. Br. Mus. nat. Hist. (Zool.) Trustees of the British Museum (Natural History), 1983 The Zoology Series is edited in the Museum's Department of Zoology Keeper of Zoology : Dr J. G. Sheals Editor of Bulletin : Dr C. R. Curds Assistant Editor : Mr C. G. Ogden ISSN 0007-1498 Zoology series Vol44 No 2 pp 75-1 90 British Museum (Natural History) Cromwell Road London SW7 5BD Issued 24 February 1983 Miscellanea Contents Cirolana cranchi Leach, 1818 (Crustacea: Isopoda: Cirolanidae) redescribed, with notes on its distribution. By N. L. Bruce & Joan Ellis Valettieta, a new genus of deep-sea amphipod (Gammaridea: Lysianassidae) with descriptions of two new species from the North Atlantic Ocean. By Roger J. Lincoln & Michael H. Thurston Three new genera of misophrioid copepods from the near-bottom plankton community in the North Atlantic Ocean. By G. A. Boxshall Larval development of British prawns and shrimps (Crustacea: Decapoda: Natantia) 4. Palaemon (Palaemon) serratus (Pennant, 1 777) and functional morphology of swimming. By A. A. Fincham The larval development of the Angular Crab, Goneplax rhomboides (Linnaeus) (Decapoda: Brachyura). By R. W. Ingle & P. F. Clark The larval and first crab stages of three Inachus species (Crustacea: Decapoda: Majidae); a morphological and statistical analysis. By Paul F. Clark . Page 75 85 103 125 163 179 Cirolana cranchi Leach, 1818 (Crustacea: Isopoda: Cirolanidae) redescribed, with notes on its distribution Niel L. Bruce Department of Zoology, University of Queensland, St Lucia, Queensland, 4067, Australia Joan Ellis British Museum (Natural History), Cromwell Road, London SW7 5BD Cirolana cranchi is considered to be the type of the genus Cirolana Leach (by monotypy, Bruce, 1981) and as Cirolana is the type genus for the family Cirolanidae (Harger, 1880; Hansen, 1890), the species is of some significance. It comes therefore as some surprise to find that C. cranchi has not been effectively described since the work of Hansen (1890). The species has frequently been considered to be indistinguishable from Cirolana parva Hansen 1890 (Stebbing, 1917; Nordenstam, 1946; Monod, 1976), and though these authors have discussed at some length the similarities of the two species, none resorted to redescription. Hale (1925) described a variety of Cirolana cranchi from South Australia. Examination of that species suggested that not only was Hale's variety quite distinct from C. cranchi, but that several closely similar species exist in the seas around Australia. It was therefore necessary to examine the holotype and specimens of Cirolana cranchi from England in order to be certain that none of the Australian species is C. cranchi. To prevent any further confusion of Cirolana cranchi with C, parva and similar related species, a new description is given here with full figures, from specimens in the British Museum (Natural History) collections. The holotype, initially stored in the British Museum's dry collections (Ellis, 1981) is in extremely poor condition, lacking most appendages, setae and spines, and is in two pieces. The holotype, taken from Cornwall was closely compared to Norman's (1904) specimen to assure conspecificity, and the description and drawings are taken from the latter. Cirolana cranchi Leach (Figs 1-3) Cirolana cranchii Leach, 1818 : 347; Gosse, 1855 : 134, Fig. 230; Hesse, 1866 : 257; Bate & Westwood, 1867:296, Fig. 5; Delages, 1881 : 156; Chevreux 1884:519; Koehler, 1886:25, 61; Bonnier, 1887: 134;Heape, 1888: 1 76; Robertson, 1888 : 76; Hansen, 1890 : 341, PI. 3, figs 3-3i; 1905:350, PI. 33. fig 3a; Stebbing, 1893 : 343; 1906 : 275; Norman, 1904 : 438; 1907 : 362; Norman & Scott, 1906:40, PI. 4; Monod, 1923: 14; 1930: 137, 145, Figs 2, 5B; 1976: 151; Larwood, 1940:33; Barrett & Yonge, 1958 : 99, Fig. 59; Crothers, 1966 : 58; Naylor, 1972 : 28, Fig. 9A-C; Ryland & Nelson-Smith, 1975 : 252; Kussakin, 1979: 191, Figs 71, 72; Bruce. 1981 : 949. Nelocira swainsonii Leach, 1818 : 347; Desmarest, 1825 : 302, PI. 48, fig. 2. Eurydice swainsonii: Milne-Edwards, 1840 : 236. Conilera grampoides Gourrett, 1 89 1 : 1 1 , PI. 1 , fig. 7, PI. 3, figs 4-1 1 . Cirolana cranchi: Marine Biological Association, 1931 : 183; 1957 : 195; Ellis, 1981 : 123. Cirolana borealis: Clarke, 1971 : 103 (Non Natatolana &0ra2//s(Lilljeborg)). Part Cirolana cranchii, Nordenstam, 1946:3, Figs 1-5. [More than one species is involved in Nordenstam's description.] Non Cirolana cranchii, Barnard, 1920 : 346; 1940 : 392, 49, 499, Fig. 66; Kensley, 1978 : 65, Fig. 27B, C.[= Cirolana vicina Barnard, 1914]. TYPE. The holotype is held by the British Museum (Natural History). Bull. Br. Mus. nat. Hist. (Zool.) 44(2): 75-84 Issued 24 February 1 983 76 N. L. BRUCE &J. ELLIS Fig. 1 Cirolana cranchi: (a)-(e), rf 17-0 mm, Polperro; (f) 9 13-3 mm, Polperro; remainder, d 14-0 mm. Plymouth, (a) lateral view; (b) cephalon, dorsal view; (c) pleon and pleotelson, dorsal view; (d) pleon, lateral view; (e) clypeal region; (0 pleon and pleotelson; (g) pereopod 1 ; (h) pereopod 7; (i) antennal peduncle; (j) pereopod 1, propodus; (k) pereopod 2; (1) pereopod 2, dactylus; (m) antennule. Scale line represents 4-5 mm. CIROLANA CRANCHI 77 Fig. 2 Cirolana cranchi: all figs d 14-0 mm except (iHO 9 13-3 mm. (a) pleopod 1; (b) appendix masculina, apex; (c) pleopod 2; (d) pleopod 3; (e) pleopod 2, medial margin of peduncle; (0 pleopod 4; (g) pleopod 5; (h) uropod, ventral view; (i) uropodal exopod, ventral view; (j) uropod, dorsal view; (k) uropodal endopod, apex; (1 ) uropodal exopod, apex; (m) sternite 7; (n) penes. 78 N. L. BRUCE &J. ELLIS Fig. 3 Cirolana cranchi: all figs from cf 14-0 mm. (a) maxilliped; (b) maxillule; (c) right mandible; (d) antenna, flagellar articles 9-11; (e) antennule, flagellar articles 4-7; (f) left mandible, incisor; (g) mandibular palp; (h) maxilla. TYPE LOCALITY. Leach (1818) gives 'Grande Bretagne' as the source of his specimens. Ellis (1 98 1 ) records the locality as Falmouth, Cornwall. MATERIAL. 2cf (17-0, 13-3 mm), Polperro, Cornwall. Coll. A. M. Norman. BM(NH) Reg 1911. 11. 8:7840-49. 2rf(14-0, 9-5 mm) 9 (12-6 mm), Plymouth, Devon. Coll. A. M. Norman. BM(NH) Reg 191 1. 11.8: 7828-30. <S (17-2 mm), 2 9 (13-0, 13-5 mm), Torquay, Devon. Coll. A. M. Norman. BM(NH) Reg 191 1. 1 1. 8: 7831-33. These specimens form part of those reported on by Norman (1904). DESCRIPTION OF MALE. Body about 2-75-3 times longer than wide. Cephalon without rostral process, interocular carina on anterior margin, dorsal interocular furrow extending from the dorsal medial margin of each eye; posterior margin of cephalon with groove on each side indicating presence of maxillipedal somite. Pereonite 1 longest, with 2 horizontal furrows on each side; pereonites 2-7 approximately subequal in length; coxal plates each with distinct carina, posterior margins of coxae 5-7 straight, projecting beyond posterior margin of segment. Pleonite 1 entirely concealed by pereonite 7; pleonite 3 with posterolateral margins moderately produced, those of pleonite 4 rounded; dorsal surfaces of pleonites with posterior margins minutely crenulate, pleonite 5 with additional small tubercles. Pleotelson slightly more than 0-66 as long as greatest width, lateral margins sinuate, converging to narrowly CIROLANA CRANCHI 79 rounded apex; posterior margins densely setose, with about 21 spines; dorsal surface flat except for two oblique anterolateral ridges. Antennule peduncle Inarticulate, articles 1 and 2 appearing fused, although suture evident; peduncular article 3 equal in length to combined lengths of articles 1 and 2; flagellum extends to posterior margin of eye. Antenna with peduncular articles 1 and 2 short, peduncular article 3 about half as long as 4, which in turn is half as long as 5; flagellum composed of about 38 articles, extends to pereonite 4. Frontal lamina pentagonal, apex not overlapped by rostral process, lateral margins slightly concave, diverging slightly, anterior margins straight; about 0-5 times as long as greatest width. Clypeus about 5-75 times wider than long. Mandibles with asymetrical incisors, that of right mandible with 3 distinctly formed subequal cusps, that of left mandible with posterior cusp prominent, central cusp broad and shallow; molar process with about 25 teeth, inferior distal margin setose, lacina mobilis with about 7 spines; mandibular palp with terminal article curved ventrolaterally, lateral margins with numerous stiff setae. Maxillule with about 10 stout spines on gnathal surface of exopod, 3 robust plumose setae on proximal half of medial margin. Maxilliped with continuous marginal setae on palp articles 3-5, marginal setae on distal margins only of palp article 2; endite with 3 terminal and 3 lateral plumose setae, and with 2 coupling hooks. Pereopod 1 with slender spines at posterior distal angle of basis; ischium with 2 setae on posterior margin and 3 setae at anterior distal angle; merus with about 6 setae at anterior distal angle, posterior margin with 3 acute spines and 5 tubercular submarginal spines; carpus with a single spine on posterior margin, set within a conspicuous indentation; propodus with 2 acute spines on palm, each spine set distally to tooth like projection, third robust spine opposes dactylus; margin of propodus minutely denticulate between spines. Pereopods 2 and 3 similar, pereopod 2 with 3 acute spines at anterior distal angle of ischium, 2 blunt spines at posterior distal angle, and third spine on the distal lateral margin; merus with 5 spines at anterior distal angle, posterior margin bisinuate, with 8 stout spines; carpus with a single stout spine and single seta on posterior distal angle, spine present on lateral distal margin; propodus with 3 spines on palm, fourth spine opposing the dactylus; dactylus with weakly developed but distinct secondary unguis, as in all pereopods. Pereopods 5-7 similar, pereopod 4 intermediate in form between anterior (1-3) and posterior (5-7) pereopods. Pereopod 7 with about 2 setae and anterior distal angles of propodus, otherwise without setae; distal angles of ischium, merus and carpus each with a group of spines; posterior margin of ischium and produs with further 3 groups of 1-4 spines; posterior margins of merus and carpus with further group of spines; propodus has spine opposing dactylus. Penes set together on posterior of sternite 7, separated from each other by about 0-05 the width of the sternite; penes are not robust, but rather lamellar flaps of cuticle which originate posteriorly, and project anteriorly, lying against sternite. Pleopods 3-5 with exopods with partial suture. Peduncles of pleopods 1-5 becoming progressively shorter towards posterior, peduncle of pleopod 1 twice as wide as long, peduncle of pleopod 4 3-5 times as wide as long; lateral distal angles each with a single spine, medial margin 3-5 coupling hooks on pleopods 1-4, pleopod 5 without coupling hooks. Pleopod 1 with rami subequal in length, endopod with margins parallel, exopod with spine at proximal lateral angle. Pleopod 2 with endopod fractionally longer than exopod; appendix masculina arises basally, extends beyond endopod by 0-1 of its length, narrows smoothly to an acute apex. Uropods extend distinctly beyond apex of pleotelson. Exopod slightly shorter than endopod, lateral margin smoothly convex, with continuous marginal setae and about 9 spines, distal half of lateral margin with dense mass of setae extending on to dorsal surface; medial margin with distinct angle half way along its length, distal half with 6 spines and dense mass of marginal setae; apex not bifid. Endopod with lateral margin angled at about 0.33 of the way along its length, proximal 0-66 densely setose, setae extending onto dorsal surface; medial margin convex with dense marginal setae and about 8 spines; apex not bifid. 80 N. L. BRUCE &J. ELLIS Fig. 4 Map showing the distribution of C. cranchi. Type locality of Nelocira swainsonii Leach, 18 18 given as Sicily. FEMALE. The only differences from the male are in the shape of the pleotelson which is wider, in the shape of the uropods which are not angled, and the lack of the dense setae on the pleotelson and uropods. DEVELOPMENT. Young males are similar to females, and the characteristic shape and setation of the uropods of large males is acquired gradually. One female has oostegites, and measured 13-3 mm. CIROLANACRANCHI 81 VARIATION. From the specimens examined, it would appear that the minute crenulations on the pleonites are not visible in large males. The presence and distribution of tubercles on the dorsal surface of the pleonites is erratic. SIZE. Hansen (1905) records the largest specimen as a female of 18.0 mm. Museum material had adult males from 9-0-1 9-1 mm, females ranged from 9-6-1 9-2 mm. COLOUR. In alcohol, all a pale tan. Barrett and Yonge (1958) describe the colour as 'very pale grey, minutely dotted on first three segments; rear edge of first seven segments marked by transverse line'. REMARKS. The shape and setation of the pleotelson and uropods are unique, and immediately separate Cirolana cranchi from all other species of Cirolana. Other characters useful in separation include the shape of the frontal lamina, the shape of the posterolateral margins of the pleonites, the length and shape of appendix masculina, the shape of the endopod of pleopod 1 , and the form of the penes. Cirolana cranchi can be separated from C. parva by the lack of a rostral point, by not having the frontal lamina overlapped by a rostral projection, and the very different shape, setation and spination of the pleotelson and uropods. DISTRIBUTION. Reliably recorded only from the eastern North Atlantic and Mediterranean. These records are summarized here together with new records from the collections of the British Museum. Fig. 4 illustrates the present distribution of Cirolana cranchi. Firth of Clyde: Cumbrae (Bate & Westwood, 1867); Fairland Point, Cumbrae (Robertson, 1888). Galway Bay, Eire: Spiddal (Ryland and Nelson-Smith, 1975); near Galway (Naylor, 1972); North Sound (Clark, 197 1 , as Cirolana borealis). Nymphe Bank: Ballycotton, County Cork, Eire (BM(NH) Collections). St George's Channel: Dale, Pembroke (Crothers, 1966). English Channel: Falmouth (BM(NH), holotype); Gwyllyn Vase, Falmouth (Stebbing, 1906); Polperro, Cornwall; Torquay (Norman, 1904); Plymouth, outside breakwater (Bate & Westwood, 1867); Batten, Mewstone Ledge, Tinside and Stoke Point, Plymouth (Marine Biological Association, 1957); Knapp Buoy, Plymouth (Heape, 1888); Torbay (BM(NH) collections); Anstis Cove, near Torquay (Stebbing, 1893); Jersey (Koehler, 1886); off St Sampson's Harbour, Guernsey (Norman, 1907); Roscoff(Delages, 1881). Bay of Biscay: Minou, Brittany (Hesse, 1866); Concarneau (Bonnier, 1887); Grands-Carneaux and east of Belle-Isle, Croisic (Chevreux, 1884); Le Croisic; Belle Isle; He d'Yeu; Guethery, near Biarritz (Hansen, 1905); Capbreton (Norman, 1904). Mediterranean: Toulon; Cannes; Porto Vecchio, Corsica; Gabes, Tunis (Hansen, 1905); Rade d'Hyeres (BM(NH) collections); Brusq, Var (Gourret, 1891, as Conilera grampoides); Villefranche (Hansen, 1890); Monaco (Monod, 1923); Sicily (Leach, 1818, as Nelocira swainsonii)', Alexandria (Larwood, 1940). Discussion Leach (1818) recorded Cirolana cranchi, the second species of what was to become the family Cirolanidae. The species then received little attention up to the revision of the family by Hansen (1890). In that publication and a later one Hansen (1905) reviewed all previous records. Records published since Hansen's two publications have basically con- tributed little towards an increased knowledge of the species. Monod (1930) figured the pleopods, and Kussakin (1979) gave new figures for the antenna, pereopods 1 and 7 and the male second pleopod, his other figures being taken from Hansen (1890). From this it can be seen that although the figures given by Hansen (1890) are of a high standard, no modern description has been given. 82 N. L. BRUCE &J. ELLIS As a consequence of the lack of detailed description Cirolana cranchi has become confused with Cirolana parva. The initiator of this confusion was Stebbing (1917) who considered C. cranchi and C. parva as likely to be synonymous. This opinion was later followed by Nordenstam (1946) who went to some length to demonstrate that the two species were one. Unfortunately, he chose to do this by illustrating pereopod characteristics, the one character likely to lead to the conclusion to which he came. Pereopods in the genus Cirolana (sens. str. Bruce, 1981) vary very little between species. Monod (1976) entered the argument in describing a Cirolana sp. from Togo, West Africa. In this paper Monod reviewed the arguments of previous authors, and discussed Hansen's (1890) diagnoses. Monod came to the conclusion that the West African species could be assigned neither to cranchi nor to parva and nor could they be said not to belong to those species. In effect, that parva and cranchi are not separable. When reviewing this debate, the most surprising aspect is that the problem existed at all. Hansen's (1890) figures clearly separate the two species. The differences in frontal lamina shape, pleotelson and uropods, presence and absence of rostral process are all clearly shown. Hansen also states that in parva the uropod apices are bifid, and in cranchi entire. It also seems remarkable that no author encountering this problem has sought to redescribe the species involved as a solution. Comparison of the figures, description and remarks given here to those of Bruce & Bowman (1982) show that Cirolana cranchi and Cirolana parva are two readily separable species. As there has been some confusion over the species included under the synonymies of Cirolana cranchi, the most important of these are now listed and discussed. Cirolana swainsonii: Miers, 1881. Examination of Miers' specimens shows that they represent a species related to, but distinct from cranchi that has yet to be described. Cirolana vicina Barnard, 1914. This species is very similar to C. cranchi and should be redescribed before final judgement on its status is passed. From Barnard's (1914) description it differs in having 'sub-bifid' uropod apices, and lacks the dense mass of setae on the uropods. Cirolana cranchii var. australiense Hale, 1925. This species is in no way a race or variety of C. cranchi. It differs in the shape of the frontal lamina, pleotelson and posterolateral margin ofpleonites2-4, and has a distinct rostral process. Cirolana cranchii: Nordenstam, 1946. Nordenstam's material came from Europe, South Africa and the Pacific, and consisted of C. cranchi., C. vicina and a species of unknown identity from the Pacific. Cirolana australiense Naylor, 1961. This species is closest to the variety described by Hale (1925), but may be a distinct species. Naylor's specimens were from the Chatham Islands, New Zealand. Cirolana sp.: Monod, 1976. Monod figures two 'Cirolana sp', one from Togo, and one from the Congo. One of these is Cirolana chaloti Bouvier, 1901 (Bruce, in press), and the other species may well be new. Monod's (1931) record of C. cranchi may be of one of these species. In conclusion, it should be emphasized that in identifying or describing species related to C. parva and C. cranchi particular care and attention should be given to details of the frontal lamina, the relative position and shape of the penes, the shape of the posterolateral margins of pleonites 2-4, the first and second pleopods of the male, and most importantly details of the pleotelson and uropods. Acknowledgements We are grateful to Dr R. J. Lincoln for his comments on the manuscript and for the loan of specimens to one of us (N. L. B.). This study was supported by a Commonwealth Postgraduate Study Award to N. L. Bruce. CIROLANA CRANCHI 83 References Barnard, K. H. 1914. Contributions to the crustacean fauna of South Africa. 3. Additions to the marine Isopoda, with notes on some previously incompletely known species. Ann. S. Afr. Mus. 10 : 325a-358a, 359-442. 1920. Contributions to the crustacean fauna of South Africa. 6. Further additions to the list of marine Isopoda. Ann. S. Afr. Mus. 17 : 319-348. 1940. Contributions to the crustacean fauna of South Africa. 12. Further additions to the Tanaidacea, Isopoda and Amphipoda, together with keys for the identification of hitherto recorded marine and freshwater species. Ann. S. Afr. Mus. 32 : 38 1-5 15. Barrett, J. & Yonge, C. M. 1958. Pocket guide to the Sea Shore. London (Collins), 272 pp. Bate, C. S. & Westwood, J. O. 1867. A history of British sessile-eyed Crustacea 2 (16-19): 209-400. London (John van Voorst.) Bonnier, J. 1887. Catalogue des crustaces malacostraces recueillis dans la Baie de Concarneau. Bull. scient. Dep. AW (2)10: 1-190. Bruce, N. L. 1981. Cirolanidae (Crustacea: Isopoda) of Australia: Diagnoses of Cirolana Leach, Metacirolana Nierstrasz, Neocirolana Hale, Anopsilana Paulian & Debouteville, and three new genera-Natatolana, Politolanaand Cartetolana. Aust. J. mar. Freshwat. Res. 32: 945-966. in press. Cirolana chaloti Bouvier (Isopoda, Cirolanidae), a long overlooked species from West Africa. Bull. Mus. natn. Hist. nat. Paris. & Bowman, T. E. 1982. The status of Cirolana parva Hansen, 1890 (Crustacea: Isopoda: Cirolanidae) with notes on its distribution. Proc. biol. Soc. Wash. 95 : 325-333. Chevreux, E. 1884. Crustaces amphipodes et isopodes des environs du Croisic. C. r. Ass. fr. Avanc. Sci. 12:517-520. Clark, F. L. 1971. Cirolana borealis Liljb. (Isopoda) on living fish from Galway Bay. Ir. Nat. J. 17: 103. Crothers, J. H. (ed.) 1966. Dale Fort marine fauna (2nd edition). London (Field Studies Council), 169pp. Delages, Y. 1881. Catalogue des crustaces edriophthalmes et podophthalmes qui habitent les plages de RoscofT. Archs Zool. exp. gen. 9 : 1 52-1 58. Desmarest, A.-G. 1 825. Considerations generates sur la classe des Crustaces, et description des especes de ces animaux, qui vivent dans la mer sur les cotes, ou dans les eaux douces de la France. Paris (F. G. Levrault), 446 pp. Ellis, J. 1981. Some type specimens of Isopoda (Flabellifera) in the British Museum (Natural History), and the isopods in the Linnaean Collection. Bull. Br. Mus. nat. Hist. (Zool)40 : 121-128. Gosse, P. H. 1855. A manual of marine zoology for the British Isles Part 1 . London (John van Voorst), 203 pp. Gourret, P. 1891. Les lemodipodes et les isopodes du Golfe de Marseille. Annls Mus. Hist. nat. Marseille. (Zool.) 4 Travaux scientifiques. Memoire No. 1, 44 pp. Hale, H. M. 1925. Review of Australian isopods of the cymothoid group. Part 1. Trans. R. Soc. S. Aust. 49: 128-185. Hansen, H. J. 1890. Cirolanidae et familiae nonnullae propinquae Musei Hauniensis. K. dansk. Vidensk. Selsk. Skr. 5 : 239-426. 1905. Revision of the European marine forms of the Cirolaninae, a subfamily of Crustacea Isopoda. J. Linn. Soc. (Zool.) 29 : 337-373. Harger, O. 1880. Notes on New England Isopoda. Proc. U.S. natn. Mus. 2 : 297-462. Heape, W. 1888. Preliminary report upon the fauna and flora of Plymouth Sound. J. mar. biol. Ass. U.K.I: 153-193. Hesse, M. 1 866. Observations biologiques sur quelques crustaces des cotes de Bretagne. Annls Sci. nat. (Zool.) (5) 5: 24 1-264. Kensley, B. 1978. Guide to the marine isopods of southern Africa. Cape Town (South African Museum), 173 pp. Koehler, R. 1 886. Contribution a 1'etude de la faune littorale des lies Anglo-Normandes. Annls Sci. nat. (Zool.) (6) 20, Art. 4. 62pp. Kussakin, O. G. 1979. Marine and brackish water isopod Crustacea. Suborder Flabellifera. Leningrad (Academy of Science, U.S.S.R.), 470 pp. (In Russian.) Larwood, H. J. 1940. The fishery grounds near Alexandria. XXI. Tanaidacea and Isopoda. Notes Mem. Fouad I Inst. Hydrobiol. Fish. 35, 72 pp. Leach, W. E. 1818. Cymothoadees In: Cuvier, F. (ed.) Dictionnaire des sciences naturelles. Paris & Strasbourg (Leurault), Vol. 12: 338-354. 84 N. L. BRUCE &J. ELLIS Marine Biological Association. 1931. Plymouth Marine Fauna 2nd edition. Plymouth: 371 pp. 1957. Plymouth Marine Fauna 3rd edition. Plymouth: 457 pp. Miers, E. J. 1881. On a collection of Crustacea made by Baron Hermann-Maltzan at Goree Island, Senegambia. Ann. Mag. nat. Hist. (5)8 : 364-377. Milne-Edwards, H. 1840. Histoire Naturelledes Crustaces. Paris (Roret), Vol. 3, 638 pp. Monod, T. 1923. Notes carcinologique (Parasites et commensaux). Bull. Inst. oceanogr. Monaco No. 427,23pp. 1930 Contribution a Petude des 'Cirolanidae'. Annls Sci. nat. (Zool.) (10) 13 : 129-183. 193 1. Sur quelques crustaces aquatiques d'Afrique (Cameroun et Congo). Revue Zool. Bot. afr. 21 1976. Remarques sur quelques cirolanides (Crustaces, Isopodes). Bull. Mus. natn. Hist. nat. Paris (Zool.) No. 251 : 133-161. Naylor, E. 1961. Some Isopoda from the Chatham Is., including two species of Cirolana new to New Zealand. Trans. R. Soc. N.Z. (Zool.) 1 : 7-17. 1972. British Marine Isopods. Synopses Br. Fauna (N.S.) No. 3, 86 pp. Nordenstam, A. 1946. Marine Isopoda from Prof. Sixten Bock's Pacific Expedition 1917-1918. Ark. Zool. 37 A (7): 1-31. Norman, A. M. 1904. British Isopoda of the families Aegidae, Idoteidae, and Arcturidae. Ann. Mag. nat. Hist. (7) 14 : 430-448. 1907. Notes on the Crustacea of the Channel Islands. Ann. Mag. nat. Hist. (7) 20 : 356-371. & Scott, T. 1906. The Crustacea of Devon and Cornwall. London (William Wesley & Son), 232 pp. Robertson, D. 1888. A contribution towards a catalogue of the Amphipoda and Isopoda of the Firth of Clyde. Proc. nat. Hist. Soc. Glasgow (N.S.) 2 : 9-99. Ryland, J. S. & Nelson-Smith, A. 1975. Littoral and benthic investigations on the west coast of Ireland. IV. (Section A: Faunistic and ecological studies.) Some shores in Counties Clare and Galway. Proc. R. Ir. Acad. 75 Sect. B: 245-266. Stebbing, T. R. R. 1893. A history of Crustacea. London (Keegan Paul, Trench, Trubner & Co. Ltd.), 466 pp. 1906. Crustacea. In: Page, W. (ed.) The Victoria history of the Counties of England. A history of the County of Cornwall. 1 : 255-289. 1917. South African Crustacea (Part IX of S.A. Crustacea, for the marine investigations in South Africa). Ann. S. Afr. Mus. 17 : 23-46. Manuscript accepted for publication 14 June 1982 Valettietta, a new genus of deep-sea amphipod (Gammaridea: Lysianassidae) with descriptions of two new species from the North Atlantic Ocean Roger J. Lincoln Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD Michael H. Thurston Institute of Oceanographic Sciences, Brook Road, Wormley, Godalming, Surrey GU8 5UB Introduction Within the gammaridean family Lysianassidae the combination of a strongly toothed mandibular incisor and unspecialized gnathopods is shared by only 4 genera, Valettia Stebbing, 1888, Alicella Chevreux, 1899, Valettiopsis Holmes, 1908 and Valettiella Griffiths, 1977. Each is monotypic with the exception of Valettiopsis which comprises 4 species, dentata Holmes, 1908, macrodactyla Chevreux, 1909, anacantha Birstein & Vinogradov, 1963 and multidentata Barnard, 1961. Barnard (1969) included one other genus, Onesimoides Stebbing, 1888, in his key to lysianassids having a toothed incisor, but there is some doubt as to the true nature of the mandibular margin. Stebbing (1888), in his description of O. carinatus says '. . . cutting edge . . . seemingly of the usual form . . .'. In O. cavimanus, the mandible has '. . . bord tranchant presque simple, renforce a chacun de ses angles par des bourrelets de chitine. . . .' (Pirlot, 1933), while in O. chelatus the cutting edge is simple (Pirlot, 1933). Those genera with a strongly dentate incisor share a broadly similar facies and can be regarded as forming a natural group, with the omission of Valettia coheres which has a quite different morphology, especially in the structure of the mouthparts. The choice of names for these genera has turned out to be rather unfortunate since the genus name Valettia was used as the stem term for the later taxa Valettiopsis and Valettiella with which it does not have close affinity. Valettiopsis and its allies live at moderate to great ocean depths and have as a conse- quence been infrequently recorded. In fact, all six species were first described from unique types, and only dentata and macrodactyla have since been redescribed from additional material (Barnard, 1967; Chevreux, 1935). Recent deep-water collections from the North Atlantic made during cruises of RRS Discovery and RRS Challenger have produced 5 mature individuals of this rare lysianassid group, one belonging to Valettiopsis macrodactyla, the other 4 representing two species new to science. The combination of characters shared by the two new species puts them close to Valettiopsis, but with sufficient disparity in the configuration of the coxal plates, pereopodal bases, and mandibular palp armature to justify the erection of a new genus for which we propose the name Valettietta gen. nov. One existing species of Valettiopsis, namely V. anacantha from the Philippine Trench in the Pacific, is transferred to the new genus. Systematics Family LYSIANASSIDAE Genus VALETTIOPSIS Holmes, 1908 DIAGNOSIS. Body robust, compressed, pleosome well developed; urosome segment 1 with Bull. Br. Mus. not. Hist. (Zool.)44(2): 85-101 Issued 24 February 1983 86 R. J. LINCOLN & M. H. THURSTON large, acute, mid-dorsal tooth, segment 3 broad and dorsally flattened with lateral margins raised. Antenna 1 and 2 elongate, slender, subequal length, peduncle articles 2-3 of antenna 1 compressed, flagellum article 1 conjoint, accessory flagellum well developed, multi- articulate. Upper lip weakly notched; lower lip without inner lobes, mandibular lobes elongate. Mandible having robust incisor, strong spine row interspersed with plumose setae, and large triturative molar; palp attached level with molar, article 2 elongate with only distomarginal setae. Maxilla 1 inner plate densely setose along entire inner margin, palp robust, 2-articulate. Maxilla 2 inner and outer plates subequal length, inner plate with dense mediodistal and facial setae. Maxilliped basic, outer plate with short inner marginal spines grading distally to robust elongate spines. Coxal plate 1 much shorter than 2 and partly con- cealed; plate 4 with only shallow posterior emargination. Coxal plate 5 anterior lobe deeper than posterior lobe. Epimeral plate 2 distal angle with tooth. Gnathopods 1 and 2 subchelate; gnathopod 1 palm transverse. Pereopod 7 basis expanded, lacking posterodistal lobe. Uropods biramous, lanceolate, spinose; uropod 3 outer ramus 2-articulate. Telson deeply cleft, each lobe with several large apical spines. Branchial lobes bearing small accessory lobe at the base. TYPE SPECIES. Valettiopsis dentata Holmes, 1908 (original designation). REMARKS. Three of the Valettiopsis species names (dentata, anacantha, multidentata) have been corrected to give the epithets feminine terminations. Holmes (1908) derived the name Valettiopsis '. . .from Valettia, a genus of Amphipods, and 6vj/is, appearance'. Greek nouns ending in ops, genitive opsis, are feminine and adjectival specific names must agree in gender with their genus name (International Code of Zoological Nomenclature, Articles 1 1 (g) (i) (D,34(b)). Valettiopsis macrodactyla Chevreux Valettiopsis macrodactyla Chevreux, 1909 p. 1 , figs 1-2; 1935 p. 8, pi. 2, fig. 1 . MATERIAL EXAMINED. 1 rf Bay of Biscay abyssal plain, about 47° 15'-28'N 8° 9'^46'W; 4300 metres; collected by Dr A. G. Macdonald during RRS Challenger cruise, October, 1978, using baited trap. BM(NH) reg. no. 1979 : 8 : 1. DESCRIPTION. Figs la-h; 2a-h; 3a-k. Length 17 mm. Body robust, compressed, pleosome segments strongly developed; urosome segment 1 with prominent dorsal tooth, upper margin of tooth weakly sinous, apex acute. Epimeral plates 2-3 (Fig. 2h) with posterodistal tooth. Head (Fig. Ib) with triangular lateral lobe apically produced and with sinuous lower margin; postantennal sinus very shallow; eyes absent. Antenna 1 elongate, peduncle article 1 slender, longer than 2-3 combined; flagellum 30-articulate; accessory flagellum 9-articulate, reaching slightly beyond end of basal conjoint article of flagellum; conjoint article of flagellum equal to length of peduncle, densely setose on inner surface; remaining flagellar articles sparsely setose. Antenna 2 longer than 1 , peduncle article 5 slightly longer and more slender than 4, flagellum 40-articulate, proximal flagellar articles with erect setules on inner margin. Upper lip (Fig. 2a) rounded with minute apical notch. Lower lip (Fig. 2b) outer lobes elongate, robustly spinulose on inner distal margin; inner lobes absent, mandibular lobes well developed. Right mandible (Fig. 2c, d), incisor robustly 7-dentate, lacinia also strongly toothed, comprising two plates with 7 and 4 teeth; spine row with 1 1 large spines interspersed with long plumose setae, distal spines dentate; molar strongly triturative; palp robust, article 3 oval with inner distal margin robustly setose, article 2 elongate, inner distal margin with long setae, inner proximal margin naked. Maxilla 1 (Fig. 2e) inner plate with entire inner margin densely setose; palp large, article 2 distal margin with stout short spines and row of submarginal setae. Maxilla 2 (Fig. 20 inner and outer plates subequal, densely setose, inner plate also with row of facial setae. Maxilliped (Fig. 2g) inner plate with 3 short apical spines; outer plate inner margin bearing row of spines that are short and stout proximally grading to elongate and plumose distally; palp elongate, article 3 with row of strong facial setae, article 4 inner margin bearing 2 short spines. VALETTIETTA GEN. NOV. 87 Fig. 1 Valettiopsis macrodactyla Chevreux. Male, a, habitus; b, head and antennae; c, gnathopod 1; d, gnathopod 1, palmar region; e, coxal plate 1, anterodistal margin; f, gnathopod 2; g, gnathopod 2, palmar region; h, coxal plate 2, posterodistal margin. Bar scales: a, b, 2-0 mm; c, f, 1 -0 mm; d, e, g, h, 0-2 mm. 88 R. J. LINCOLN & M. H. THURSTON Fig. 2 Valettiopsis macrodactyla Chevreux. Male, a, upper lip; b, lower lip; c, right mandible; d, lacinia mobilis and spine row, right mandible; e, maxilla 1 ; f, maxilla 2; g, maxilliped; h, pleon. Bar scales: a-g, 0-5 mm; h, 2-0 mm. VALETTIETTA GEN. NOV. 89 Gnathopod 1 (Fig. 1 c, d) subchelate, coxal plate short, triangular, apically rounded, antero- distal margin with small tooth (Fig. le), distal margin setulose; basis with long setae on anterior and posterior margins; ischium elongate; merus short with mat of short setules on posterior margin; carpus little longer than propodus, setose on posterior margin; propodus rectangular, strongly setose, palm transverse (Fig. Id), delimited by group of stout spines, palmar margin minutely toothed; dactylus short, slightly overlapping palm, inner margin with small tooth. Gnathopod 2 (Fig. If, g) subchelate; coxal plate rectangular, posterodistal margin with 2 small teeth (Fig. Ih); basis with many long setae on anterior and posterior margins; ischium elongate; merus small; carpus equal to length of propodus, posterior margin densely setose; propodus robust, densely setose, palm oblique (Fig. Ig) convex, delimited by group of large dentate spines, palmar margin smooth; dactylus stout with small tooth on inner margin. Pereopod 3 (Fig. 3a), coxal plate rectangular, distal margin weakly sinuous, posterodistal angle with 2 small teeth (Fig. 3b); basis curved, merus robust; carpus shorter than propodus. Pereopod 4 (Fig. 3c) similar to 3, except coxal plate with broad shallow posterior emargination, distal margin without tooth. Pereopods 5-7 (Figs 3d, e, f) robust, spinose; basis with tapering posterior lobe, distal angle weakly produced on 5, not produced on 6-7, bearing 1-2 slender submarginal spines, posterior margin weakly serrate, distal margin of basal lobe on pereopod 7 bevelled. Uropods biramous, spinose; uropod 1 (Fig. 3g) rami subequal, inner margins of rami minutely serrate; uropod 2 (Fig. 3h) outer ramus little shorter than inner; uropod 3 (Fig. 3i) distal article of outer ramus about one-third length of proximal article, inner margin of inner ramus setose. Telson (Fig. 3j) elongate triangular, cleft to three-quarters length, inner apical margin rounded, outer apical angle (Fig. 3k) with 4 graduated spines. DISTRIBUTION. Known only from the North Atlantic in the region of the Azores (Chevreux, 1 935) at 1 692-1 919m, and from the present Biscay record at 4300 m. VALETTIETTA gen. nov. DIAGNOSIS. Body robust, compressed; pleosome well developed; urosome segment 1 with weak dorsal process, segment 3 broad and flattened dorsally with lateral margins raised. Antenna 1 and 2 elongate, slender, about equal length; peduncle articles 2-3 of antenna 1 compressed, flagellum article 1 conjoint, accessory flagellum well developed, multi- articulate. Upper lip weakly notched. Lower lip without inner lobes, mandibular lobes prominent. Mandible with robustly dentate incisor, spine row strong, interspersed with plumose setae, molar large and triturative, palp attached level with molar, article 2 elongate with proximal and distal margin setose. Maxilla 1 inner plate densely setose along entire inner margin, palp robust, 2-articulate. Maxilla 2 inner and outer plates subequal length, inner plate with dense mediodistal and facial setae. Maxilliped basic; outer plate with short stout inner marginal spines grading distally to robust elongate spines. Coxal plates 1-4 forming continuous series; plate 4 with deep posterior emargination. Coxal plate 5 anterior lobe not deeper than posterior lobe. Gnathopod 1 subchelate; palm oblique; gnathopod 2 subchelate or simple. Pereopods 5-7 basis expanded with prolonged rounded posterodistal lobe. Uropods biramous, lanceolate, spinose. Telson triangular, deeply cleft. Branchial lobes with small accessory lobe close to base. TYPE SPECIES. Valettietta lobata sp. nov. ETYMOLOGY. The affinity of the new genus to Valettiopsis is recognized by adding the diminutive ending -etta to the common stem. Gender feminine. Valettietta lobata sp. nov. MATERIAL EXAMINED. Holotype d, Bay of Biscay abyssal plain, about 47°15'-28'N 8°9'^6'W; 4300 metres; collected by Dr A. G. Macdonald during RRS Challenger cruise 1980, using baited trap. BM(NH) reg. no. 1982 : 204. 90 R. J. LINCOLN & M. H. THURSTON Fig. 3 Valettiopsis macrodactyla Chevreux. Male, a, pereopod 3; b, coxal plate 3, posterodistal margin; c, pereopod 4; d, pereopod 5; e, pereopod 6; f, pereopod 7; g, uropod 1 ; h, uropod 2; i, uropod 3; j, telson; k, apex of telson lobe. Bar scales: a-f, 1 -0 mm; g-j, 0-5 mm. VALETTIETTA GEN. NOV. 91 Fig. 4 Valettietta lobata sp. nov. Holotype. a, habitus; b, head and antennae; c, gnathopod 1 ; d, gnathopod 1, palmar region; e, gnathopod 2; f, gnathopod 2, palmar region; g, coxal plate 2, posterodistal margin. Bar scales: a, 5-0 mm; b, 2-0 mm; c, e, 1 -0 mm; d, f, g, 0-2 mm. 92 R. J. LINCOLN & M. H. THURSTON Fig. 5 Valetlietta lobata sp. nov. Holotype, a, left mandible; b, left mandible, incisor, lacinia and spine row; c, right mandible, incisor, lacinia and spine row; d, upper lip; e, lower lip; f, maxilla 1 ; g, maxilla 2; h, maxilliped; i, pleon. Bar scales: a, d-h, 0-5 mm; b, c, 0-2 mm; i, 2-0 mm. VALETTIETTA GEN. NOV. 93 Paratype d1, Discovery station 9541 # 19, north west of Cape Verde Islands, RMT 1 +8 combination net, 18 April 1977, 4040-3970 m (fished 0-20 metres off bottom); 20°19-T N 21°51-3' W-20°184' N21°40-5' W. BM(NH) reg. no. 1982 : 205. ETYMOLOGY. The epithet refers to the expansive posterior lobe of the pereopod basis. DESCRIPTION. Figs 4a-g; 5a-i; 6a-m. Holotype. Length 21-5 mm. Body robust, compressed, pleosome segments strongly developed; urosome segment 1 with small rounded median knob-like process bearing pair of minute apical spinules. Epimeral plate 2 (Fig. 5i) distal angle quadrate, plate 3 distal angle acute. Head (Fig. 4b) large, lateral lobe triangular, postantennal sinus very shallow; eyes absent. Antenna 1 elongate, peduncle article 1 slender, posterodistal angle with small tooth, articles 2-3 short, flagellum 34-articulate; accessory flagellum 10-articulate, reaching little beyond end of basal conjoint article of flagellum; conjoint article 1 equal to length of peduncle, densely setose on inner surface, remaining flagellar articles sparsely setose. Antenna 2 little longer than 1, peduncle articles 4-5 subequal length, flagellum 48-articulate, proximal articles with erect setules on posterior margin. Upper lip (Fig. 5d) asymmetrically rounded with small apical notch, distal surface minutely setulose. Lower lip (Fig. 5e) outer lobes elongate, robustly spinulose on inner distal margin, inner lobes absent, mandibular lobes elongate. Mandible (Fig. 5a, b, c), left incisor robustly 8-dentate and closely applied to 6-dentate lacinia; right incisor 7-dentate, well spaced from double bladed lacinia bearing numerous small teeth; spine row with 12-13 large spines interspersed with long plumose setae, distal spines dentate; molar strongly triturative; palp robust, article 3 oval with inner margin spinose, article 2 elongate with regular row of long inner distal setae and irregular groups of shorter proximal setae. Maxilla 1 (Fig. 50 inner plate with entire inner margin densely setose, outer plate with 2 rows (6 and 5) of pectinate spines; palp large, article 2 distal margin with stout spines and row of submarginal setae. Maxilla 2 (Fig. 5g) inner and outer plates subequal, distally setose, inner plate also with row of facial setae. Maxilliped (Fig. 5h) inner plate with 3 short apical spines, outer plate inner margin with row of short stout spines becoming gradually more elongated and plumose distally; palp elongate, article 3 with row of strong facial setae, article 4 inner margin with 2 small teeth. Gnathopod 1 (Fig. 4c, d) subchelate; coxal plate rounded, distal margin with small tooth, inner distal surface with about 8 groups of setae; basis short, anterior and posterior mid-margins with long setae; ischium elongate, setose; merus short, margin with mat of short setules; carpus shorter than propodus and robustly setose; propodus sub- rectangular, robust, densely setose, palm weakly oblique (Fig. 4d), smooth, delimited by fan-like group of 6 spines (3 on inner face, 3 on outer face); dactylus short, just reaching to end of palm. Gnathopod 2 (Fig. 4e, 0 subchelate, longer and more slender than 1 ; coxal plate subrectangular, posterodistal margin with 2 small teeth (Fig. 4g), inner distal surface with about 6 groups of 2-5 setae; basis slender, anterior and posterior margins setose; ischium elongate; merus small; carpus equal to length of propodus, densely setose; propodus sub- rectangular, setose, palm weakly oblique (Fig. 4f) convex, delimited by fan-like group of 6 spines; dactylus short, not reaching end of palm; gnathopod 2 with characteristic twist in appendage between basis and merus that reverses the orientation of distal articles. Pereopod 3 (Fig. 6a), coxal plate slender, rectangular, posterodistal angle with 2 small teeth (Fig. 6b); basis curved; merus elongate slender and much longer than carpus; dactylus small, straight. Pereopod 4 (Fig. 6c) similar to 3, except coxal plate with broad moderately deep posterior emargination, posterodistal margin with small notch (Fig. 6d). Pereopods 5-7 (Fig. 6e, f, g), robust, spinulose; basis broadly expanded with large posterodistal lobe that becomes more angular from 5 to 7, posterior margin finely serrate; coxal plate of pereopod 6 with posterior lobe distinctly angular. Uropods biramous; uropod 1 (Fig. 6h) rami subequal, robustly spinose; uropod 2 (Fig. 6i) inner ramus just shorter than outer, spinose, adjacent margins minutely serrate; uropod 3 (Fig. 6j) distal article of outer ramus about one-third length of proximal article, apex with pair of minute inset setules (Fig. 6k). Telson elongate triangular (Fig. 61), cleft to three-quarters length, inner apical margin acute, outer angle with 2 spines set in groove (Fig. 6m); dorsal surface of telson flattened with lateral margins downturned. 94 R. J. LINCOLN & M. H. THURSTON Fig. 6 Valettietta lobata sp. nov. Holotype. a, pereopod 3; b, coxal plate 3, posterodistal margin; c, pereopod 4; d, coxal plate 4, posterodistal margin; e, pereopod 5; f, pereopod 6; g, pereopod 7; h, uropod 1; i, uropod 2; j, uropod 3; k, apex inner ramus of uropod 3; 1, telson; m, apex of telson lobe. Bar scales: a, c, e-j, 1,1-0 mm; b, d, 0- 1 mm. VALETTIETTA GEN. NOV. 95 Fig. 7 Valettietta gracilis sp. nov. Holotype. a, habitus; b, gnathopod 1 ; c, gnathopod 1 palmar margin; d, gnathopod 2; e, gnathopod 2 propodus, distal margin; f, urosome, telson. Bar scales: a, 2-0 mm; b, d, f, 0-5 mm; c, e, 0- 1 mm. 96 R. J. LINCOLN & M. H. THURSTON REMARKS. The paratype male, body length 18 mm, has essentially similar morphology to the holotype; antenna 1 flagellum 25-articulate with especially obvious tooth on peduncle article 1; antenna 2 flagellum 36-articulate bearing calceoli. The structure of the calceolus (Fig. 10) was examined by SEM and was found to approximate to the basic lysianassid form described by Lincoln & Hurley (1981), but with certain unique features that set it apart from all other lysianassid calceoli described to date. These include the 4 broad crescentic plates that form the distal element and the lack of a cuticular pit at the point of origin of the stalk from the flagellar article. Valettietta gracilis sp. nov. MATERIAL EXAMINED. Holotype rf, Bay of Biscay abyssal plain, about 47°15'-28'N 8°9'^6'W; 4300 metres; collected by Dr A. G. Macdonald during RRS Challenger cruise 1980, using baited trap. BM(NH) reg. no. 1982 : 206. Paratype cf, Discovery Station 9541 * 19 north west of Cape Verde Islands, RMT 1 +8 combination net, 18 April 1977, 4040-3970 m (fished 0-20 m off bottom); 20°19-T N 21°51-3' W-20°18-4'N21°40-5' W. BM(NH) reg. no. 1982 : 207. ETYMOLOGY. The epithet alludes to the slender condition of the gnathopod 2 propodus. DESCRIPTION. Figs 7a-f; 8a-h; 9a-h. Holotype. Length 1 1 mm. Body compressed, pleosome segments well developed; urosome segment 1 with rounded median process. Epimeral plates 1-2 posterodistal angle obtuse (Fig. 8h), plate 3 acutely produced. Head large (Fig. 8a), lateral lobes triangular, apically rounded; postantennal sinus very shallow; eyes absent. Antenna 1 elongate, flagellum 3 1 -articulate, sparsely setose; accessory flagellum 7-articulate, reaching beyond end of basal conjoint article of flagellum; conjoint article equal to length of peduncle article 1 , densely setose on inner surface. Antenna 2 little shorter than 1 , peduncle articles 4 and 5 subequal length, flagellum 30-articulate, proximal flagellar articles with erect setules on posterior margin. Upper lip asymmetrically rounded with small apical notch, distal surface minutely setulose. Lower lip (Fig. 8b) outer lobes elongate, inner distal margin robustly spinulose, inner lobes absent, mandibular lobes elongate. Mandible (Fig. 8c, d), left incisor strongly 8-dentate and closely applied to 7-dentate lacinia; right incisor 8-dentate, well spaced from 6-dentate lacinia; spine row with 13 large spines interspersed with long plumose setae, distal spines dentate, molar strongly triturative; palp robust, article 1 small, article 2 extremely elongate with regular row of inner distal setae and irregular groups of proximal setae, article 3 oval with robust marginal setae. Maxilla 1 (Fig. 8e, 0 inner plate setose along entire inner margin, outer plate bearing two rows of pectinate spines; palp large, article 2 distal margin with stout spines and row of long submarginal setae. Maxilla 2 inner and outer plates subequal, distally setose, inner plate also with row of facial setae. Maxilliped inner plate with 3 short apical spines; outer plate inner margin with row of short stout spines (Fig. 8g) becoming gradually elongate and plumose distally; palp elongate, setose. Gnathopod 1 (Fig. 7b, c) subchelate; coxal plate rectangular, anterior margin angular, distal margin setose; ischium long and setose; merus small, posterior margin with mat of short setules; carpus much shorter than propodus, posterior margin densely setose; propodus elongate, tapering distally, anterior and posterior margins with long setae; palm oblique (Fig. 7c) convex, dentate, delimited by group of short spines; dactylus overlapping palm, inner margin toothed. Gnathopod 2 simple (Fig. 7d, e), coxal plate rectangular, distal margin setose, smooth; basis curved, anterior and posterior margins setose; ischium extremely elongate; merus small; carpus slender, sparsely setose; propodus slender, tapering distally, margin with groups of long setae that curve inwards to form a setal basket, palm absent but propodal margin with solitary spine close to the closing point of the dactylus. Gnathopod 2 with characteristic twist in appendage between basis and merus that reverses the orientation of the distal articles. Pereopod 3 (Fig. 9a) coxal plate rectangular, distal margin setose; basis curved; merus longer than carpus; propodus and carpus subequal length; all articles with long marginal spinules. Pereopod 4 (Fig. 9b) similar to 3, except coxal plate very broad and VALETTIETTA GEN. NOV. 97 Fig. 8 Valettietta gracilis sp. nov. Holotype. a, head and antennae; b, lower lip; c, left mandible; d, right mandible; e, maxilla 1 ; f, maxilla 1 palp; g, maxilliped outer plate; h, pleon. Bar scales: a, h, 1-0 mm;b-g, 0-2 mm. 98 R. J. LINCOLN & M. H. THURSTON Fig. 9 Valettietta gracilis sp. nov. Holotype. a, pereopod 3; b, pereopod 4; c, pereopod 5; d, pereopod 6; e, pereopod 7; f, uropod 1; g, uropod 2; h, uropod 3. Bar scales: a-e, 1 -0 mm; f-h, 0-5 mm. Fig. 10 Valcttietta lobata sp. nov. Scanning electron micrographs of antennal calceoli; a, b, d sectional photographs of same calceolus, bar scale: 5-0 (im; c, entire calceolus, bar scale 10 |im. 1 00 R. J. LINCOLN & M. H. THURSTON deeply excavate posteriorly, distal margin straight and setose; merus and propodus subequal and longer than carpus. Pereopods 5-7 (Fig. 9c, d, e) robust, spinulose; basis broadly expanded with large posterodistal lobe that becomes more angular from 5 to 7, posterior margin minutely serrate; coxal plate of pereopod 6 with subangular posterior lobe. Uropods biramous; uropod 1 (Fig. 90 and uropod 2 (Fig. 9g) inner ramus shorter than outer, spinose, adjacent margins minutely serrate; uropod 3 (Fig. 9h) distal article of outer ramus two-thirds length of proximal article, apex of proximal article with triangular tooth, inner margin of inner ramus setose, apex of both rami with inset small setule. Telson (Fig. 70 triangular, cleft beyond three-quarters length, apex acute with small spinule. DISCUSSION. The new genus Valettietta shares a general appearance and many special features with Valettiopsis, but is characterized by the following combination of characters: fully developed coxal plate 1; obtuse epimeral plate 2; produced posterodistal lobes on pereopods 5-7 bases; groups of proximal setae on article 2 of mandibular palp. The species anacantha described by Birstein & Vinogradov from a deep-sea station in the Pacific south of the Philippines is transferred to Valettietta; it is very close to gracilis but can be distinguished by the rounded shape of coxal plate 4 and the presence of a short palm on the propodus of gnathopod2. Key to species of Valettiopsis and Valettietta gen. nov. 1 Coxal plate 1 reduced; urosome with strong acute tooth . . . (VALETTIOPSIS) 2 Coxal plate 1 not reduced; urosome lacking strong acute tooth (VALETTIETTA gen. nov.) 4 2. Pereon segments 5-7 and pleosome segments 1-3 dorsally dentate .... multidentata Pereon segments 5-7 and pleosome segments 1-3 not dorsally dentate 3 3. Gnathopod 2 propodus elongate, tapering dentata Gnathopod 2 propodus stout, ovo-rectangular macrodactyla 4. Gnathopod 2 simple, or with very small palm, propodus slender, tapering .... 5 Gnathopod 2 subchelate, propodus not slender, ovo-rectangular .... lobata sp. nov. 5. Gnathopod 2 palm oblique, coxal plate 4 distal margin convex anacantha Gnathopod 2 lacking palm, coxal plate 4 distal margin straight .... gracilis sp. nov. Valettietta gracilis and V. anacantha can be regarded as vicarious species having disjunct distributions, one from the Atlantic Ocean and the other from the Pacific Ocean. The differences separating them, although considered valid at species level, are of a minor nature, and are much less marked than those separating either species from Valettietta lobata. Within Valettiopsis, the Pacific species dentata and the Atlantic macrodactyla form a similar species pair. Other Atlantic/Pacific species pairs are known; Paracallisoma alberti Chevreux, 1903 and P. coecum (Holmes, 1908), and Crybelocephalus birsteini Thurston, 1976 and C. obensis Birstein & Vinogradov, 1964. The separation of the Atlantic and Pacific elements of these species pairs may have occurred in the geologically recent past. All are meso- to abyssopelagic, and have been found in areas that were contiguous prior to the emergence of the Isthmus of Panama about 3-5 x 106yearsB.P. (Keigwin, 1978). References Barnard, J. L. 1961. Gammaridean Amphipoda from depths of 400 to 6000 meters. Galathea Rep. 5 : 23-128. 1967. Bathyal and abyssal gammaridean Amphipoda of Cedros Trench, Baja California. Bull. U.S. natn. Mus. 260 : 1-205. 1969. The families and genera of marine gammaridean Amphipoda. Bull. U.S. natn. Mus. 271 : 1-535. Birstein, J. A. & Vinogradov, M. E. 1963. The deep-sea pelagic amphipods of the Philippine Trench. Trudy Inst. Okeanol. 71 : 8 1-93 (In Russian). 1964. Pelagic gammarids of the northern part of the Indian Ocean. Trudv Inst. Okeanol. 65: 152-195. VALETTIETTA GEN. NOV. 101 Chevreux, E. 1899. Sur deux especes geantes d'Amphipodes provenant des campagnes du yacht Princesse Alice. Bull. Soc. zool. Fr. 24: 1 52-1 58. 1903. Note preliminaire sur les Amphipodes de la famille Lysianassidae receuillis par la Princesse Alice dans les eaux profondes de TAtlantique et de la Mediteranee. Bull. Soc. zool. Fr. 28: 8 1-97. 1909. Diagnoses d'Amphipodes nouveaux provenant des campagnes de la Princesse Alice dans 1'Atlantique nord. Bull. Inst. oceanogr. Monaco 150 : 1-7. 1935. Amphipodes provenant des campagnes du Prince Albert ler de Monaco. Result. Camp. sclent. Prince Albert I 90 : 1-2 14. Griffiths, C. 1977. The South African Museum's Meiring Naude cruises. Part 6 Amphipoda. Ann. S. Afr. Mus. 14(4): 105-123. Holmes, S. J. 1908. The Amphipoda collected by the U.S. Bureau of Fisheries Steamer 'Albatross' off the west coast of North America, in 1903 and 1904, with descriptions of a new family and several new genera and species. Proc. U.S. natn. Mus. 35 : 489-543. Keigwin, L. D., Jr. 1978. Pliocene closing of the Isthmus of Panama, based on biostratigraphic evidence from nearby Pacific Ocean and Caribbean Sea cores. Geology, Ashtead6(\0) : 630-634. Lincoln, R. J. & Hurley, D. E. 1981. The calceolus, a sensory structure of gammaridean amphipods (Amphipoda: Gammaridea). Bull. Br. Mus. nat. Hist. (Zool.) 40 (4) : 103-1 16. Pirlot, J. M. 1933. Les amphipodes de 1'expedition du Siboga. Deuxieme partie. Les amphipodes gammarides. II. Les amphipodes de la mer profonde. I. Siboga Exped. 33c (1 20): 1 1 5-1 67. Stebbing, T. R. R. 1888. Report on the Amphipoda collected by H.M.S. Challenger during the years 1873-1876. Rep. sclent. Results. Voy. Challenger (Zoology) 29 : 1-1737. Thurston, M. H. 1976. New pelagic amphipods (Crustacea: Amphipoda) collected on the Sond cruise. J. mar. biol. Ass. U.K. 56: 143-159. Manuscript accepted for publication 10 June 1982 Three new genera of misophrioid copepods from the near-bottom plankton community in the North Atlantic Ocean G. A. Boxshall Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD Introduction Only three species of the copepod order Misophrioida have been described, Misophria pallida Boeck 1864, Benthomisophria palliata Sars 1909 and B. cornuta Hulsemann & Grice 1964. Despite the small number of species the misophrioids have attracted interest because of the combination of characters that they exhibit, drawn from both the gymnoplean and podoplean lineages within the Copepoda. Attention has recently been drawn to the unique characters that misophrioids display; the possession of a carapace-like posterior extension of the cephalosome, the lack of a nauplius eye in a free living copepod, the distensibility of the gut and the retention of the antennary glands as the functional excretory organs of the adult (Boxshall, 1982). These characters, together with the abbreviated lecithotrophic nauplius phase of the life cycle, can be interpreted collectively as evidence of a bathypelagic origin of the Misophrioida. This interpretation is supported by the discovery of several new misophrioid taxa from the deep North Atlantic Ocean, which was reported at the First International Conference on Copepoda held at Amsterdam in August 1981 (Boxshall, in press). A total of 37 misophrioids was taken in a single haul fished near the bottom in 3000 m of water to the south west of the Azores. Fourteen of these were B. cornuta, 8 were B. palliata and 15 represented previously undescribed taxa. Three new genera and species are here described on the basis of 13 of these specimens, the remaining 2 specimens being too badly damaged for description. The new genera are of great phylogenetic significance as they exhibit some very plesiomorphic characters which provide fresh insights on the nature of the appendages of the common ancestor of the Copepoda as a whole. The new records of B. cornuta and B. palliata further extend their known geographical ranges. Family MISOPHRIIDAE Genus ARCHIMISOPHRIA nov. DIAGNOSIS. As for type species. TYPE SPECIES. Archimisophria discoveryi gen. et sp. nov. Archimisophria discoveryi gen. et sp. nov. Adult female (Fig. 1A) body length 1-1 to 14 mm. Prosome large, apparently 4-segmented but with first free thoracic somite entirely concealed beneath a carapace-like extension from the posterior margin of the maxilliped-bearing somite. Nauplius eye absent. Prominent anteriorly-directed rostrum visible from dorsal aspect, not fused to labrum (Fig. 1 B). Cone organs not observed but large mass of glandular tissue present on sides of cephalosome beneath usual location of cone organs. Urosome 6-segmented (Fig. 1C). Surface Bull. Br. Mus. nat. Hist. (Zool.) 44(2): 103-124 Issued 24 February 1983 104 G. A. BOXSHALL Fig. 1 Archimisophria discovery! gen. et sp. nov. Holotype 9. A, dorsal view; B, rostrum and labrum, ventral; C, urosome, ventral; D, antennule, dorsal. Scales 100 urn unless otherwise stated. MISOPHRIOID COPEPODS 105 of prosome and urosome somites 1 to 5 ornamented with a reticulum of epicuticular lamellae. Urosome somite 6 without reticulate markings. Caudal rami longer than wide; armed with 2 long distal margin setae, 2 medium-length distal angle setae, a dorsal seta near the inner margin and a distally located lateral seta. Antennule (Fig. ID) 27-segmented, articulating proximally with an expanded area of ventral cephalic surface (Fig. IB). Armature elements as follows: 1-2, II-2, III-2+1 aesthetasc, IV-2, V-2, VI-2, VII-2 + 1 aesthetasc, VIII-2, IX-2, X-2, XI-2+1 aesthetasc, XII-2, XIII-2, XIV-2, XV-2, XVI-2+1 aesthetasc, XVII-2, XVIII-2, XIX-2, XX-2, XXI-2, XXII-1, XXIII-1, XXIV-2, XXV-2, XXVI-2 + 1 aesthetasc, XXVII-5+1 aesthetasc. First segment also with patch of minute spinules. Labrum (Fig. IB) small, posteriorly directed, not fused with rostrum, with a posterior row of marginal denticles. Antenna (Fig. 2A), basis lacking inner distal seta; endopod 3-segmented, exopod 8- segmented. Endopod segment 1 apparently unarmed; segment 2 with 4 unequal unilaterally plumose setae at inner distal angle; segment 3 with 6 long subequal unilaterally plumose setae along distal margin and with several transverse rows of spinules. Exopod segment 1 with a short naked seta at inner distal angle; segments 2 and 3 unarmed; segment 4 with a long plumose seta at inner distal angle; segment 5 with 2 long plumose setae on inner margin; segments 6 and 7 small, unarmed; segment 8 with 3 long unilaterally plumose setae on distal margin and areas of spinules subapically. Mandible (Fig. 2B) with well developed gnathobase bearing distally 2 multicusped blades, 5 strong spines and an extensive fringe of pinnules. Mandibular palp comprising basis, 2 -segmented endopod and 4-segmented exopod. Basis armed with a naked seta at inner distal angle. Endopod segment 1 with a short unilaterally plumose seta at inner distal angle; segment 2 with 8 unequal plumose setae along distal margin. Exopod segment 1 unarmed; segments 2 and 3 each with 1 long seta at inner distal angle; segment 4 with 3 similar unilaterally plumose setae and a short naked seta. Maxillule (Fig. 2C), gnathobase with 14 distal elements; endite 1 with 1 spiniform and 3 setiform armature elements, endite 2 with 3 spiniform elements. Outer lobe rudimentary, represented by 6 plumose setae on outer surface of segment. Maxillulary palp biramous with 2 -segmented endopod and 1 -segmented exopod. Endopod segment 1 with 3 unequal armature elements at inner distal angle; segment 2 with a long and a short seta proximally on inner surface and an apical armature of 3 long unilaterally plumose setae, 1 long and 2 short naked setae. Exopod with a proximal fringe of pinnules and 6 plumose setae on inner margin and with 3 long unilaterally plumose setae and a naked seta on distal margin. Maxilla (Fig. 3A) 6-segmented; segment 1 with 6 plumose setae on proximal endite and 3 on distal endite; segment 2 with 3 similar setae on both proximal and distal endites; segment 3 produced medially into a curved claw armed with 3 naked setae near its base; segments 4 to 6 with a total of 10 setae. Maxilliped (Fig. 2D) 8-segmented, with a 3-segmented, robust proximal portion and a slender 5-segmented distal portion. Segment 1 with 1 seta on inner surface; segment 2 with 2 medial setae and a row of pinnules along the outer margin; segment 3 with proximal endite bearing 1 strong spine and 3 setae, distal endite with 1 naked seta and a long plumose seta, 2 other setae on inner margin, a plumose seta at inner distal angle and a long row of pinnules along outer margin; segments 4 to 6 with 1, 2 and 1 medial setae respectively, each armed with short spinules; segment 7 with an inner margin spinulate seta and an outer plumose seta on which the pinnules decrease markedly in length towards the apex; segment 8 with 3 similar plumose setae and a naked seta. Legs 1 to 4 incomplete in holotype 9 and paratype 9, assumed to be similar to those described below for a paratype rf. Leg 5 (Fig. 1C) uniramous, 3-segmented and positioned midventrally with inner margins almost touching at base. Segment 1 with 1 naked seta at outer distal angle; segment 2 with a short naked seta in same position; segment 3 elongate with 2 unequal distal margin setae, the longer armed with spinules bilaterally. G. A. BOXSHALL Fig. 2 A. discoveryi. A, antenna, anterior; B, mandible, anterior; C, maxillule, posterior; D, maxilliped, posterior. Scales 100 |im unless otherwise stated. MISOPHRIOID COPEPODS 107 Fig. 3 A. discoveryi. A, maxilla, anterior; B, Paratype cf, dorsal view; C, urosome, ventral; D, antennule, dorsal. Scales 100 fim unless otherwise stated. 108 G. A. BOXSHALL Leg 6 (Fig. 1C) reduced to a semicircular flap closing off the opening of the genital antrum; bearing an outer plumose seta and a short inner spine. Adult male (Fig. 3B) body length 1-1 to 1-3 mm (based on 3 specimens). Prosome and urosome (Fig. 3C) as in adult female. Appendages as in female except for antennules and legs 5 and 6. Antennules (Fig. 3D) 25-segmented, unigeniculate with the articulation between segments XIX and XX. Armature elements as follows: 1-2, II-2, III-2, IV-2, V-2, VI-2, VII-2, VIII-2, IX-2, X-2, XI-2 + 1 aesthetasc, XII-2, XIII-2, XIV-2, XV-4, XVI-2+1 aesthetasc, XVII-2, XVIII-2, XIX-2, XX-0(?), XXI-1, XXII-2, XXIII-2, XXIV-2+1 aesthetasc, XXV-3 + 1 aesthetasc. Segment XIII with a spinous process at posterolateral angle. Legs 1-4 (Figs 4A-D) biramous with 3-segmented rami; armature formula as follows: coxa basis endopod exopod legl 0-1 1-1 0-1;0-1;1,2,3, I-1;I-1;III,I,3 leg 2 0-1 1-0 0-1;0-2;1,2,3 I-1;I-1;1 11,1,4 leg 3 0-1 1-0 0-1;0-2;1,2,3 I-1;I-1;III,I,4 Ieg4 0-1 1-0 0-l;0-2;missing I-1;I-1;1 11,1,4 Pinnule rows present on inner and outer margins of endopod segments and inner margins of exopod segments; spinules present along margins of exopod segments. All outer margin exopodal spines armed with bilateral strips of fine membrane, apical spine with membrane externally and pinnules internally. All setae plumose except for distalmost 2 inner margin setae on exopod of leg 4. These setae with blunt tips and rows of short stout pinnules, possibly representing a male dimorphic character. Leg 5 (Fig. 4E) uniramous, 4-segmented and with bases of legs almost touching at ventral midline as in 9. Segment 1 bearing 1 plumose seta at outer distal angle; segment 2 with naked seta in same position; segment 3 with plumose seta at inner distal angle; segment 4 with short inner margin plumose seta and 2 unequal plumose setae on distal margin. Leg 6 (Fig. 3C) represented by a flattened plate bearing a long outer plumose seta and a short inner spine. MATERIAL EXAMINED. Holotype 9, 3 paratype cfd1, 19,2 Copepodid IV and 3 Copepodid III stages all from Discovery Stn 10379*37 (34°5T N 32°55' W) in the North Atlantic to the southwest of the Azores. Collected in RMT1+8M net system fished 23 to 56 m off the bottom in a water depth of about 3000 m. BM(NH) Registration Nos Holotype 9 1982.128, paratype 9 1982.129, rfrf 1982.130-132,Co. IV 1982. 133-134 and Co. Ill 1982.135-137. REMARKS. The new genus differs from all known misophrioids, including those described herein, in the possession of an anteriorly directed rostrum. In other genera the rostrum is either ventrally directed (Misophria and Misophriopsis gen. nov.) or postero ventral ly directed and fused to the labrum (Benthomisophria and Misophriella gen. nov.). Another remarkable feature of this genus is the large number of segments in the antennules of both sexes. The twenty-seven segments found in the female is the largest number recorded for any copepod, including the calanoids in which 25 is the largest number known. The phylogenetic significance of the multi-segmented antennules is discussed below. The developmental stages of A. discovery! will not be described as only the third (Co. Ill) and fourth (Co. IV) copepodid stages have been found. As in other misophrioids (Boxshall & Roe, 1980) the copepodid stages can be determined by the number of urosome somites, the Co. Ill having 3 and the Co. IV having 4. It is interesting to note that the segmentation of the antennule is complete (27 segments) at the Co. IV stage whereas in Benthomisophria palliata the complete complement of 1 8 segments is not achieved until the last moult into the adult. The third copepodid of A. discoveryi has a 24-segmented antennule. The presence of a 3-segmented leg 5 in female and 4-segmented leg 5 in male A. discoveryi MISOPHRIOID COPEPODS 109 Fig. 4 A. discoveryi. A, leg 1 , anterior; B, leg 2, anterior; C, leg 3, anterior; D, leg 4, anterior; E, leg 5, anteroventral. Scales 100 urn unless otherwise stated. 110 G. A. BOXSHALL is the first documented example of sexual dimorphism in the fifth leg in misophrioids. In Misophria and Benthomisophria sexual dimorphism is restricted to the antennules and sixth legs. The presence of modified setae on the inner margin of the third exopod segment of leg 4 in male A. discoveryi may also represent sexual dimorphism but this cannot be confirmed until more material is obtained, as the only 2 females in the present material had incomplete fourth legs. Genus MISOPHRIELLA nov. DIAGNOSIS. As for type species. TYPE SPECIES. Misophriella tetraspina gen. et sp. nov. Misophriella tetraspina gen. et sp. nov. Adult female (Fig. 5 A) body length 0-87 mm (Holotype 9). Prosome apparently 4-segmented but, as in all misophrioids, with the first free thoracic somite entirely concealed beneath a carapace-like extension of the posterior margin of the maxilliped-bearing somite. Nauplius eye absent. Rostrum posteroventrally directed and fused to anterior surface of labrum, not visible from dorsal aspect. Cone organs present in lateral areas on cephalosome. Urosome 6-segmented (Figs 6A-B), somites 2 to 5 each with a hyaline frill around posterior border. Anal somite with paired lobes dorsally, either side of anus and row of minute spinules around posterior margin. Pairs of pores present on both dorsal and ventral surfaces of anal somite. Caudal rami about as long as wide, armed with 2 long distal margin setae, 2 medium length distal angle setae, a dorsal seta near the distal margin, a seta near the middle of the lateral margin and a proximal setule on this margin. Antennule (Fig. 5B) 19-segmented, articulating basally with a raised area of ventral cephalic surface. Armature elements as follows: 1-1, II-9, III-2, IV-2, V-6, VI-2, VII-2, VIII-2, IX-2+ 1 aesthetasc, X-2, XI-2+ 1 aesthetasc, XII-2, XIII-2, XIV-2 + 1 aesthetasc, XV-1, XVI-1, X VII-2, X VIII-2 + 1 aesthetasc, XIX-6+ 1 aesthetasc. Segment I with 1 and segment II with 3 strong curved setae, each strongly sclerotized with an expanded base and a row of spinules along its convex margin. Labrum large, posteriorly directed and fused with rostrum. Antenna (Fig. 5C); basis with inner distal seta; 3-segmented endopod and 6-segmented exopod. Endopod segment 1 with a short plumose seta at inner distal angle; segment 2 with 2 short naked setae near middle of inner margin and a long and a short seta at inner distal angle; segment 3 with 6 long unilaterally plumose setae along its distal margin. Exopod segment 1 unarmed; segments 2 to 5 each with a single long, unilaterally plumose seta on its inner margin; segment 6 with 2 similar setae and a short plumose seta on its distal margin. Mandible (Fig. 7A) with well developed gnathobase bearing 4 multicusped blades and some pinnules distally. Mandibular palp comprising basis, 2-segmented endopod and 4-segmented exopod. Basis apparently lacking inner distal angle seta. Endopod segment 1 with 1 naked seta at inner distal angle; segment 2 with 1 short naked seta and 4 long plumose setae apically. Exopod segment 1 unarmed; segments 2, 3 and 4 with 1 , 2 and 3 long plumose setae respectively. Maxillule (Fig. 7B) with armature of gnathobase reduced, comprising only 7 curved spinous elements, 1 hirsute seta and 2 slender naked setae. Endites 1 and 2 with 5 and 4 slender setae respectively; all setae sparsely armed with short spinules bilaterally. Outer lobe apparently absent. Maxillulary palp biramous with 1 -segmented exopod and 3-segmented endopod. Endopod segment 1 fused to basis, with 3 unequal plumose setae at inner distal angle; segment 2 with 2 inner margin plumose setae; segment 3 small, bearing 4 unequal setae apically. Exopod with 3 long plumose setae distally and a short plumose seta and a row of pinnules along inner margin. Maxilla (Fig. 7C) 6-segmented; segment 1 with 2 hemispherical endites, proximal endite with 1 naked and 4 plumose setae, distal endite with 2 spinulate setae; segment 2 with a MISOPHRIOID COPEPODS 111 Fig. 5 Misophriella tetraspina gen. et sp. nov. Holotype 9. A, dorsal view; B, antennule, dorsal; C, antenna, anterior. Scales 50 Jim unless otherwise stated. 112 G. A. BOXSHALL Fig. 6 M. tetraspina. A, urosome, dorsal; B, urosome, ventral. Scale 100 |im. single elongate endite bearing 3 unequal naked setae at its apex; segment 3 produced into a long medial claw with a fringe of minute pinnules along its concave margin and 3 setae near its base; segments 4 to 6 each with 1 long, robust claw-like seta armed with a fringe of pinnules, segment 6 also bearing 2 slender apical setae. Maxilliped (Fig. 7D) 7-segmented; segments 1 and 2 long and robust. Segment 1 armed with 1 proximal seta, 3 midmargin setae and 2 distal setae all on inner margin; segment 2 with 3 slender setae at middle of inner margin; segments 3 to 5 with 1, 2 and 1 slender inner margin setae respectively; segment 6 with an articulated seta distally and segment 7 with 2 similar articulated setae, plus 2 short naked setae. Legs 1-4 (Figs 8 A-D) biramous, presumably with 3-segmented rami; armature formula as follows: legl leg 2 leg 3 leg 4 coxa 0-1 0-1 0-1 0-1 basis 1-1 1-0 1-0 1-0 endopod 0-1 ;0-2; 1,2,3 0-1 ;missing 0-l;0-2;missing 0-l;0-2;missing exopod I-l;missing I-l;missing Pinnule rows present on inner and outer margins of endopod segments and on inner margins of exopod segments. Leg 1 with accessory digitiform processes on outer margin of exopod segments 2 and 3 between bases of spines. Exopod spines armed with bilateral strips of serrate membrane. Leg 5 (Fig. 8E) uniramous, 4-segmented. Segment 1 broader than long, unarmed; segment MISOPHRIOID COPEPODS 113 2 broader than both segments 1 and 3, armed with a naked seta on outer margin; segment 3 with spinous process at outer distal angle; segment 4 with 1 plumose seta either side of central spine in distal margin, also with an inner margin plumose seta on left leg but not on right. Leg 6 (Fig. 6B) forming a curved plate on ventral surface of genital somite; armature incomplete. MATERIAL EXAMINED. Holotype 9 collected at Discovery Stn 10379*37 (34°57 N 32°55'W) in the North Atlantic southwest of the Azores. Caught in RMT1 + 8M net system fished 23 to 56 m off the bottom in a water depth of about 3000 m. BM(NH) Registration No. 1982-138. REMARKS. The new genus differs from all known misophrioids, including those described herein, in the form of the maxillule (which has a 3 -segmented endopod, no outer lobe and an elongate exopod bearing only 4 setae), in the presence of only a single endite on the second segment of the maxilla and in the number of segments in the antennule. This genus exhibits a general reduction in the numbers of armature elements on most of the mouthparts, particu- larly on the maxillulary palp and the maxilla. In addition to these quantitative differences there are also qualitative differences, such as the spiniform nature of 4 setae on the proximal segments of the antennule and the presence of articulated setae on the maxilliped. The armature elements of the fifth legs provide some indication of the homology of the segments. The second segment carries an outer seta at its distal angle and it is also much wider than the other segments. It probably represents the basis. Segment 1 therefore represents the coxa, and segments 3 and 4 the 2-segmented exopod. The holotype exhibits bilateral asymmetry in the armature of leg 5 but it is assumed that this is an aberrant con- dition and is not indicative of a true asymmetry as displayed by the fifth legs of many calanoids. Genus MISOPHRIOPSIS nov. DIAGNOSIS. As for type species. TYPE SPECIES. Misophriopsis dichotoma gen. et sp. nov. Misophriopsis dichotoma gen. et. sp. nov. Adult female (Fig. 9 A) body length 0-9 mm (Holotype 9). Prosome apparently 4-segmented but with first free thoracic somite entirely concealed beneath a carapace-like extension from the posterior margin of the maxilliped-bearing somite. Nauplius eye absent. Rostrum small, ventrally directed with its apex adjacent to, but not fused to, the labrum (Fig. 12). Cone organs present in lateral areas on either side of cephalosome. Urosome (Fig. 9B) 6-segmented. Caudal rami wider than long, armed with 2 long distal margin setae, a medium length seta at both inner and outer distal angles, another on the dorsal surface near bases of distal setae, and a short lateral seta. Antennule (Fig. 9C) 18-segmented. Armature elements as follows: 1-1, II-l 1, III-2, IV-6, V-2, VI-2, VII-2, VIII-2 + 1 aesthetasc, IX-2, X-2+ 1 aesthetasc, XI-2, XII-2, XIII-2+ 1 aesthetasc, XIV-1, XV-1, XVI-2, XVII-2 + 1 aesthetasc, XVIII-6+1 aesthetasc. Spinules present on posterior surface of segment II. Labrum (Fig. 12) large, posteriorly directed but not fused with rostrum; armed with 2 large medially directed spinous processes on its posterior margin. Antenna (Fig. 9D) basis lacking inner distal seta; endopod 3 -segmented, exopod 6-segmented. Endopod segment 1 with 2 inner distal setae; segment 2 with 3 setae spaced along inner margin; segment 3 with 5 long distal margin setae. Exopod segment 1 unarmed; segment 2 with 2 inner margin setae; segments 3 to 5 each with a single seta at inner distal angle; segment 6 with 3 plumose setae. Mandible (Fig. 9E) with well developed gnathobase bearing distally 4 multicusped blades, 114 G. A. BOXSHALL Fig. 7 M. tetraspina. A, mandible, anterior; B, maxillule posterior; C, maxilla, anterior; D, maxilliped, posterior. Scale 100 |im. MISOPHRIOID COPEPODS 115 Fig. 8 M. tetraspina. A, leg 1 , anterior; B, leg 2, anterior; C, leg 3, anterior; D, leg 4, anterior; E, leg 5, antero ventral. Scales 100 ^im unless otherwise stated. 116 G. A. BOXSHALL Fig. 9 Misophriopsis dichotoma gen. et sp. nov. Holotype 9 A, dorsal view; B, urosome, ventral; C, antennule, dorsal; D, antenna, anterior; E, mandible, posterior; F, detail of mandibular gnathobase. Scales 100 (im unless otherwise stated. MISOPHRIOID COPEPODS 117 several strong spines and a small subapical patch of pinnules. Mandibular palp comprising basis, 2-segmented endopod and an indistinctly 5-segmented exopod. Basis armed with a plumose seta midway along inner margin. Endopod segment 1 with plumose seta at inner distal angle; segment 2 elongate with 4 unequal setae on distal margin. Exopod segments 1 and 2 incompletely separated; segment 1 unarmed; segments 2 and 3 each with a plumose seta at inner distal angle; segment 4 probably with inner seta, missing from dissected appen- dage but its presence indicated by a scar on the surface of the segment; segment 5 with 1 inner and 2 distal margin setae. Maxillule (Fig. 10 A), gnathobase with 7 distal margin spines, 2 hirsute setae and 3 naked setae subapically on the posterior surface, and 2 plumose setae on a spinulate swelling on the anterior surface. Endite 1 short and slightly furrowed on its posterior surface, armed with 6 apical plumose setae. Endite 2 long, with 3 apical plumose setae. Outer lobe rudimentary, represented by 8 plumose setae on outer surface of segment. Maxillulary palp biramous with 2-segmented endopod and 1 -segmented exopod; segment 1 of endopod fused to basis, with junction marked by 2 subapical setae. Endopod segment 1 with 4 plumose setae at inner distal angle; segment 2 with 3 naked setae arising proximal to the midpoint of the inner margin, 3 similar setae arising subapically on same margin, and 5 setae on distal margin. Exopod with 9 plumose inner and distal margin setae of varying lengths and with fringes of long pinnules proximally. Maxilla (Fig. 1OB) 6-segmented; segment 1 with 5 plumose setae on proximal endite and 3 on distal endite; segment 2 with 3 plumose setae on both proximal and distal endites; segment 3 produced medially into a curved claw armed with 2 naked setae near its base; segments 4 to 6 with a total of 7 naked setae. Maxilliped (Fig. IOC) 7-segmented, although proximal segment showing some signs of subdivision at midlength. Segment 1 bearing 4 plumose setae and a short naked seta along inner margin, and some long pinnules proximally on outer margin; segment 2 with 3 inner margin plumose setae; segments 3 to 6 each with 2 long, unilaterally plumose setae at inner distal angle; segment 7 with 3 distal setae. Legs 1-4 (Figs 1 1 A-D) biramous, with 3-segmented rami. Armature formula as follows: coxa basis endopod exopod legl 0-1 I-I 0-1;0-2;1,2,3 I-1;I-1;III,I,4 Ieg2 0-1 1-0 0-1;0-2;1,2,3 I-1;I-1;III,I,5 leg 3 0-1 1-0 0-l;0-2;missing I-1;I-1;III,I,5 leg 4 0-1 1-0 0-l;0-2;missing I-1;I-1;III,I,5 Outer margins of all exopod segments with strips of serrated membrane. Rows of pinnules present on inner margins of all exopod segments and inner and outer margins of endopod segments. Outer margin spines of leg 1 armed bilaterally with fine strips of smooth membrane. Apical spines with short pinnules along inner margins, and strip of smooth membrane on outer margin in leg 1. Outer margin element on basis spinous on leg 1, setiform on legs 2 to 4. Leg 5 (Fig. 1 1 E) biramous, comprising unsegmented protopod, 2-segmented exopod and 1 -segmented endopod. Basal seta present at outer distal angle of protopod. Exopod segment 1 unarmed, segment 2 with 3 distal margin elements, a long plumose outer seta, a median spine and an inner naked seta. Endopod with single plumose seta apically. Leg 6 (Fig. 1 1 F) with transverse intercoxal sclerite joining members of leg pair reduced to a slender bar. Leg comprising an outer process with a long apical seta, a median spine and an inner spinous process. MATERIAL EXAMINED. Holotype 9 collected at Discovery Stn 10379*37 (34°57 N 32°55' W) in the North Atlantic to the southwest of the Azores. Caught in RMT1 +8M net system fished 23 to 56 m off the bottom in a water depth of about 3000 m. BM(NH) Registration No. 1982-139. 118 G. A. BOXSHALL Fig. 10 M. dichotoma. A, maxillule, posterior; B, maxilla, anterior; C, maxilliped, anterior. Scales 100|im. MISOPHRIOID COPEPODS 119 Fig. 11 M. dichotoma. A, leg 1 , anterior; B, leg 2, anterior; C, leg 3, anterior; D, leg 4, anterior; E, leg 5, anteroventral; F, leg 6, ventral. Scales 1 00 ^im unless otherwise stated. 120 rostrum G. A. BOXSHALL antennule antenna labrum paragnath intermaxillary swelling mandibular palp Fig. 12 M. dichotoma. Ventral view of mouthparts of left side, with antennule, left paragnath and mandibular gnathobase removed. Scale 100 urn. REMARKS. The new genus differs from all known misophrioids, and from all known podopleans, in the possession of a biramous fifth leg. It also differs from other misophrioid genera in the presence of a pair of large spinous processes on the posterior margin of the labrum. The arrangement of the mouthparts (Fig. 12) is very similar to that of Benthomisophria palliata. The antennae and mandibular palps are both reflexed so that their setae will sweep over the areas of cone organs located laterally on the cephalosome as in Benthomisophria. Key to genera and species of the Misophrioida 1. Large anteriorly directed rostrum visible in dorsal view; antennule with 25 (rf) or 27 (9) segments Archimisophria discovery! Rostrum ventrally or postero ventral ly directed, not visible in dorsal view; antennule with less than 25 segments 2 2. Leg 5 biramous, with 1 -segmented endopod and 2-segmented exopod .... Misophriopsis dichotoma Leg 5 uniramous, with 1 to 4 segments 3 3. Leg 5 4-segmented, antennule with 19 segments (9) . . . Misophriellatetraspina Leg 5 with less than 4 segments, antennule with less than 1 9 segments (9) .... 4 4. Leg 5 3-segmented; antennule with 1 3 segments (d) or 1 6 segments (9) Misophria pallida Leg 5 2-segmented, comprising a triangular proximal segment and short distal segment; antennule with 18 (9) or 16 (d1) segments Benthomisophria palliata Leg 5 1 -segmented; antennule with 16 segments (9 & rf) B.cornuta MISOPHRIOIDCOPEPODS 121 Discussion These three new genera exhibit between them an unusual array of plesiomorphic characters, many of which are present in a state approaching that attributed to the hypothetical ancestor of the Copepoda as a whole (see discussion in Boxshall et al., in press). The antennae, for example, are biramous with an 8-segmented exopod and a 3-segmented endopod in Archimisophria, and the mandibles have a well developed gnathobase plus a biramous palp with a 5 -segmented exopod and 2 -segmented endopod in Misophriopsis. The basic structure of both these limbs is the same as that proposed for the ancestral copepod. The detailed structure of the maxillule was not considered in the discussion reported by Boxshall et al. (in press) but in my opinion the misophrioid pattern of large gnathobase, 2 other endites, 1 setose outer lobe, a 1 -segmented exopod and a 3-segmented endopod, with the first segment fused to the basis, may well be similar to that possessed by the ancestral copepod. The misophrioid maxilla comprises 6 segments, the first 2 each bear a pair of setose endites, the third a claw-like endite, and the fourth to sixth variable number of inner and distal setae. This is close to what may be considered to be the ancestral copepod pattern. The 8-segmented maxilliped of Archimisophria consisting of a 3-segmented protopod and 5-segmented endopod is also very similar to the 9-segmented basic copepod maxilliped favoured by Gurney (193 1) in his analysis of copepod appendages. All these misophrioid features closely approximate to those exhibited by the plesiomorphic calanoids. It is the common possession of these calanoid-like gnathostomatous mouthparts and the possession of a heart that indicates that the Misophrioida diverged from the podoplean lineage soon after its separation from the gymnoplean lineage. The discovery of a 27-segmented antennule in Archimisophria and of a biramous fifth leg in Misophriopsis clearly demonstrates that the Misophrioida has diverged less from the common ancestral stock of the Copepoda than any other podoplean group. The possession of a biramous fifth leg is of great phylogenetic significance. The difference between the normal biramous fifth swimming leg of gymnopleans and the reduced uniramous fifth leg of podopleans led Giesbrecht (1899) to suggest the possibility that they are not homologous. Gurney (1931) rejected this and suggested that the typical uniramous leg of podopleans represents the exopod of an originally biramous limb. This interpretation has been widely adopted and the presence, in Misophriopsis, of a biramous fifth leg in which the endopod is reduced to a single segment bearing a single seta provides further confirmation. The fifth leg undergoes considerable reduction within the Misophrioida. In Misophria the endopod is represented by a single median seta on the distal margin of the unsegmented protopod, although the exopod is similar to that found in Archimisophria. In Benthomisophria cornuta the fifth leg is reduced to a single segment. The 27-segmented antennule of female Archimisophria is of interest because of the con- siderable controversy that exists (see Boxshall et al, in press) concerning the nature of this limb in the ancestral copepod. Giesbrecht (1892 & 1899) analysed the segmentation and armature of the antennules of many calanoid and other copepods in an attempt to reduce the antennule of all copepods to a common type. Giesbrecht's basic copepod antennule was 25-segmented and by studying the arrangement of the armature elements he was able to determine which segments had fused in those forms with fewer segments. This basic limb closely resembles that ofCalanusfinmarchicusGunnerus, 1770 both in number of segments and in setation. The typical armature present on each antennulary segment is 2 setae and 1 aesthetasc, at least in the female, although one or more of these elements is often lost, most commonly the aesthetasc. Even the arrangement of these 3 elements, which Giesbrecht called a 'trithek', follows a constant pattern. One seta, the proximal seta, is positioned about midway along the anterior margin of the segment whereas the other seta, the distal seta, and the aesthetasc are positioned close together at the distal angle of the anterior margin. The typical trithek may have been different for the male, because a proximal and a distal seta plus 2 distal aesthetascs are commonly found, as for example, in Eucalanus attenuatus Dana, 1849. Some of the more distal segments have modified tritheks. In female Calanus 122 G. A. BOXSHALL CO <*/"> <N < <N < r5 u w •£•£ 1g ^ o vo £» r- 5*8 5j <N fN fN O-o ^2 •S rt ^ O_ (^> "^ n ^ "> *^ ^ ' <N fN fN| c i •«'« c CL ^ ex ^ CL ^j •£ u *•••, •c « 3 Q ^ •o £ Q^ «| c "^ <L> .5 $J Q S __. <N ^s ro ~ <N U (N al ^a i c3 c r, O"1* •" fN H fS |-s 08 '> "o. H 22 4-1 (N ^" fN su o CX f* c S I H r: _ ON ^0 -s'S oo ed t"1 _^ *- °° [^ ON <-> " 3 a o - c .ti u u H - •^ — H 22 •* — Be ^ g .£} O H 2 H — f— ' ^ ;S'H t*. '£ 8 II f- 2 ~ £ H^ u a £ (8 ^•<-> D. c f- 2 ^2! H ^ « O g « u"S O C ^^1 — S 0 O *•" — - — H _- g g v5 0 [_ 0 -2 H^ — ca 3 u o o C/) C/] Is c '.s H ON H = H2 '•5 c « ff D aj H oo *- 2 H " " i C ^_i 3 - • rt E. H r- ^ o H 2 O O Zi •£'•- c o j^ ^M \^ •"00 H ON ^ ts E d'5 H «n [— i r- H oo o 5 — ^ O."™ O JS o *-• f- •* *•" NO [— i (~~ •C-£.§ *o c n^ ^^i ^ -0 H MD 7i"5 §• 11 Hl ^N ^^ ^•••••l l/~) ^'|< CO |> h" ^-(N •^•^ r^j ^H "^^ jr'C u £ o hJ ^ (N H f«^ •cli 2 to .2 — XJ c .a ^}- C/3/ C/5 — 111 el 0 7~~ 3 ^ «2 H « 3 11 .••j -c "fi 2|^ Table 1. The st podoplean (Arch Calanus finmarc armature segmentation UN .<3 C «? C * -B 1 -B g, Oj> rt § CJ ^ •a ^H g § o| g ^ ! £ g? Is^?? Jj^co % §Sco3i5 ^ ^ U a JU C 3 "oo ea j •S 2 2 a.l.l -C O O ^ a a MISOPHRIOID COPEPODS 123 finmarchicus segments 20 and 21 have no proximal seta, segments 22, 23 and 24 have no proximal seta but have instead a distal seta on the posterior margin, and the terminal segment 25 has an increased armature of up to 6 setae and an aesthetasc (see Table 1). As Gurney (193 1) noted, many calanoids possess 3 complete tritheks on the second segment and a single proximal seta plus a distal trithek on the first segment. He interpreted this as evidence that the second segment of calanoid antennules is derived from 3 fused segments and that the first segment may be derived from 2 fused segments. On the basis of this interpretation he postulated that the ancestral copepod antennule comprised 27 or possibly 28 segments. The discovery of Archimisophria with its 27-segmented antennules provides a remarkable corroboration of Gurney 's hypothesis. Comparison between the antennules of female Calanus finmarchicus and Archimisophria discoveryi is made in Table 1. The precise correspondence in the position of typical tritheks, denoted by T or t, and of modified tritheks, denoted by D or d and P or p, in these two taxa is remarkable as they are drawn from the 2 main copepod lineages, Gymnoplea and Podoplea. It is possible from the comparison in Table 1 to identify a common pattern from which both may be derived by reduction. I suggest that this pattern may well represent that found in the common ancestor of the Copepoda. Functional interpretation of the unique characters exhibited by misophrioids (Boxshall, 1982 & in press) suggests that the ancestral misophrioid stock became adapted to a bathypelagic existence and to gorging as a feeding strategy. The group appears to have radiated in the deep-sea near-bottom environment and it is probable that many new misophrioid taxa will be discovered as the near-bottom community is subject to more intense study. Despite their obvious specializations the misophrioids also retain many characters of the presumed ancestral copepod stock and it is clear that they diverged from the ancestral podoplean stock soon after it had attained its characteristic division into prosome and urosome. Acknowledgements I would like to thank P. M. David and Dr Howard Roe of the Institute of Oceanographic Sciences for permission to work on this material and for arranging for it to be donated to the BM(NH) collections. I am also grateful to Dr Roger Lincoln for reading and commenting on the manuscript. References Boeck, A. 1864. Oversigt over de ved Norgs Kyster iagttagne Copepoder henhevende tie Calanidernes, Cyclopidernes og Harpacticidernes Familiar. Fork. VidenskSelsk. Krist. 1864 : 226-28 1 . Boxshall, G. A. 1982. On the anatomy of the misophrioid copepods, with special reference to Benthomisophria palliata Sars. Phil. Trans. R. Soc. Lond. B. 297 : 125-181. in press. The functional morphology of Benthomisophria palliata Sars, with a consideration of the evolution of the Misophrioida. Crustaceana, Suppl. in press. Boxshall, G. A., F. D. Ferrari & H. Tiemann. in press. The ancestral copepod: towards a consensus of opinion at the First International Conference on Copepoda. Crustaceana, Suppl. in press. Boxshall, G. A. & H. S. J. Roe. 1980. The life history and ecology of the aberrant bathypelagic genus Benthomisophria Sars, 1909 (Copepoda: Misophrioida). Bull. Br. Mus. nat. Hist. (Zool.)38 : 9-41. Dana, J. D. 1849. Conspectus Crustaceorum quae in orbis terrarum circumnavigatione, Carolo Wilkes e classe Reipublicae Foederatae duce, lexit et descripsit Jacobus D. Dana. Proc. Am. Acad. ArtsSci.2: 8-61. Giesbrecht, W. 1892. Systematik und Faunistik des pelagischen Copepoden des Golfes von Neapel und der angrenzenden Meeresabschnitte. Fauna Flora Golfo Napoli 19: 1-83 1 . 1899. Die Asterocheriden des Golfes von Neapel und der angrenzenden Meeresabschnitte. Fauna Flora Golfo Napoli 25 : 1-2 1 7. Gunnerus, J. E. 1770. Nogle smaa rare mestendelen nye norske S0dyr beskrevene. Skr. Kiobenhavnske Selsk. Laerd. og Videnskab. Elsk. 10 : 175. 124 G. A. BOXSHALL (in nicy, R. 1931. British Fresh-water Copepoda Vol. 1 . Ray Society, Lond. Hulsemann, K. & Grice, G. D. 1964. A new bathypelagic species of Benthomisophria (Copepoda: Misophriidae) from the North Atlantic. Zoo/. Anz. 173 : 259-264. Sars, G. O. 1909. Note preliminaire sur trois formes remarquables de copepodes provenant des Campagnes de S.A.S. Le Prince Albert de Monaco. Bull. Inst. Oceanogr. Monaco. 147 : 1-8. Manuscript accepted for publication 9 June 1 982 Larval development of British prawns and shrimps (Crustacea: Decapoda: Natantia) 4. Palaemon (Palaemon) serratus (Pennant, 1777) and functional morphology of swimming A. A. Fincham Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD Introduction Palaemonid shrimps are widely distributed in the N.E. Atlantic being found in fresh water, in estuaries, intertidally and down to 40 m offshore, but their larvae are rare in the plankton. All decapod larvae have a natural tendency to sink (Foxon, 1934) and in order to maintain position at a particular depth (Savage, 1926) and perform daily vertical migrations (Russell, 1925, 1927; Hardy & Bainbridge, 1954), active upward swimming is necessary also. Foxon measured rates of movement in various decapods including pandalid carideans and several authors have noted the effect of light and gravity on the orientation and movement of decapod larvae (Sollaud, 1921;Gurney, 1942; Forward &Cron in, 1978). The aim of this paper is to review the larval development of Palaemon (Palaemon) serratus (Pennant, 1777) and report on morphological adaptations, and a mechanism using many-jointed plumose setae fringing the thoracic exopods, for larval swimming. Materials and Methods Rearing Ovigerous Palaemon (Palaemon) serratus were trawled from 12 m in April 1979 from Plymouth Sound, Devon (Grid reference: SX 475512). Similar rearing techniques to those reported previously (Fincham 1977, 1978, 1979) were used with the following modifications: 1 . The controlled temperature room was at 1 4 °C. 2. Antibiotics were used for the first three stages only (Fincham, 1979). Larval material has been deposited in the Crustacea collection of the BM(NH), registration number 1982 : 186. Telson morphology The telson was removed from larvae by a cut at the narrow junction with the abdomen, rinsed in distilled water, freeze dried, mounted end-on with Araldite on stubs, coated with gold and examined with a scanning electron microscope. Palaemon (Palaemon) serratus (Pennant, 1 777) Astacus serratus Pennant, 1777 Melicerta triliana Risso, 1816 Palaemon trilianus Risso, 1826 Palaemon treillianus H. Milne Edwards, 1837 Leander latrei/lianus Czerniavsky, 1 884 Bull. Br. Mus. not. Hist. (Zool.)44(2): 125-161 Issued 24 February 1983 125 126 A. A. FINCHAM — II ^^> — 1 „ 1 I ^ E r-Qi C* 0 03 A 0 +11 E "\ A /A 8. ^ rs ON ON ^ ON fl O + n 1 1 £ ' O T + 1 <N I 7 A o 7 i + i 3 2 r*! f* ~^ 00 °° ON 00 a ^ i OO rO O + f^i + ' 1*^ h 3l +tti- 00 — 1 7 u o "? i + i 00 ON r-~ oo ^ O i ^ r*"i ^5 + (^i ^ ll ^ZZ +Qi_ ( (N J7 II o 7 | + | 00 ON + ^" pr> 0 r~ oo o 1 zz 1 § VO m O + <N 1 . 1 — rn - 1 4 v ° 2 ' + ' (N 00 ON r- oo g $ 'Z — — vO C _fc • . . . JT: £ l/~> rn O + fN + 1 ' + Oi — — • 1 | O O oo (— , ^ | _j_ | r-~ oo _2 ^ rn . *"" . Tt O O <N c Z - - <N rN c Tt ro O + «N + 1 ^T + 1 — — 1 ,^,•^0 — Q + O+ i .(- i r~ oo 0 j^J V *"*°P «N *^ Tf ro O O <N fN fi a •g 3 ea 0 — — (N fN > 0 1 «*» <N O + — b (U ^ + i- — 1 . *"* . ON *"" — sO 1^ C/5 i_ c O O — <N 03 O (U C z __ _ C CN * ' * * lf\ 73 Z <N — O -f- — + I ai 1 o — 1 ^^ JO O Jj | ~rO~r i _i_ i \o t~^ C . »• ^j j^^ T^ . ^^ */^ ^"^ r*1** en u ."2 "3 <N ^L^ ^^ ^^ ^^ "5 O _3 i s Z — — '5b II (N • • • • oj Q Q or o 1 - oo N 1 0 1 + > 1 1 0 — 1 -3 2^^> + I + I 6 6 ^ SO-O ex c 0 ^5 g c 'o.c u CJ 00 || c M 2 1 •o l/f 1 — __ c/5 c U J i « 03 *~* (L> opment a present/y c/5 V C '5. 1 C/5 (U '5. + ^ E "O "t~ tS 0) 11 I C 1 £ S 2 1 ^ C C <U ^ 4- 4> C c« _)_ ' SOO jj ' c/5 !i 3 u _^ s?^ -g li t^ 'C 0.0 0 « U oa able 1 Larval devel . = rudimentary; + = arapace No. of dorsal spines No. of ventral rostra Supraorbital spines No. of antero-iatera J1 1 TJ o tn it: 1 y; .9- H r 1 c *- _ + \ <u is sil I g S '£ ^^ S> | 88^ °^ c >. « o ccessory flagellum + ntenna 2 <3 W ^_3 e« g d| 2£ l.i Z — ° ° ir c ^ ""* C^ . . QJ * ^™ d, 1 « oo « «J5 " S« Z Z uu j a. ^'o ' i o _r « i &S — O oo T3 X) 'S ™ 9 --5 C (U O. = UJ -J 0 axilla 1 No. of endite setae - f* 06 U < v5 v5 Z « uu ^ 2 LARVAL DEVELOPMENT OF P. (P.) SERRA TVS 1 27 CN! O O rf. Tt VO ON -T^^ OO^M "-> + + -^ + + +C* + + + + + + I + I+ + + ++ 1^+^^ A A A /A T^- A A >/-> o _k co so r«-> rvi ON , m rn vor^l -II TJ- + + ^+ + + + + + + + + +1 + I +-~ + + + I ^ + J. ' NO Tt -«o i^^t — x — . r (N — — rs S o^ I + £ 0+^7 £ ~£™ + 5^ 22£ ps) -)- , , ~ ON 7 -ON- ^ + + -0 + + + + + + + + + +I + i ed i i i xj + ° + 2 2 — JH — rN i +1 +01 \+ +O + r- ; - Coxa Basis 1 Basis 2 Endopodite tae exopodite :ernal margin - Coxa Basis if setae- Lateral t/5 (75 "c c 0 (U S £ oo oo D D CO C/5 podus fixed finger +/ c 0 1 £ ii 1 1 concave ( — ) or convex ( + ) 03 u SB c u d d + 0 "5 '•£ 03 c « 00 CO c 6 Z^l Z^ 1 CL | i i 1 I 1 0 O C <L> <L> '2? <u O o i _j_ i j d^ ^^ 1 J- ^^ ^ ^ ^ ^ O3 C.^ i _03 c 03 ,*J E <u i <L> 3J + 1> + + + + + + — •» 1 <U "~ E T3 3 ~~ O3 o c^i .ti i> 1 ro •'ti <u 1 '~* C/2 • — f^ 'f- *r f IO C/5 1 1 . co x ^ C h«2 _os o 5- "8 0 ;§• o3 OO <*. 0 "O 0 a 13 o -5 + a; o -5 a o. o ^ a o- o •_r o a <L> -^ o a + •§ 4j O. O E 0 T3 a o o a I"8 E a I"8 c a o c 11 v) **O ~r 0) D co is"8 11 ob <u ^ C P. C- _o 'C u '1? ° X --7 03 Z o ~ "^^ 0 Z o X U o5 UJ UJ C/D 03 UJ tU !/5 *- £ UJ H ||; 1 — QJ 1> si c c a O O o OO GO D £<l to o CL s 2 S 2 cx a. IX CL < £ H "8.2 a-o o o •o a c x UJ PU ^ 1 t- (/) -— ^*4 'V" 3 ^5 + c o 'a °. 45 ^ « «« £ ^ a <u ~ D. D. 00 C ^ • O C 'a E 5jtr o C/5 OO xC -J -J 128 A. A. FINCHAM Leander serratus Sharp, 1 893 Leander treillianus Adensamer, 1 898 Leander serratus var. treillianus De Man, 1915 Palaemon (Palaemon) serratus Holthuis, 1950 SYNOPSIS OF LARVAL DATA FROM PUBLISHED WORK. Thompson, 1 836 zoeae I, III & V, p. 22 1 , Figs 1-5, laboratory reared and plankton. Couch, 1845 zoea I, p. 20, no Figs, laboratory reared. Mayer, 1877 zoea I, telson, p. 250, Fig. 49. Keeble and Gamble, 1904 zoea I, chromatophores, p. 316. Sollaud, 1912 zoeae I-IX, p. 664, no Figs, laboratory reared. Williamson, 1915 zoea II (not I), Figs 120-125, zoea I Figs 126-128, last zoea Figs 129-132, p. 396, plankton. Sollaud, 1923 zoeae I-IX & post larva I, p. 530, plates 16-18 (Figs 1^ only), laboratory reared and plankton. Reeve, 1969 zoeae I-V (XI), p. 77, no Figs, laboratory reared. Sutton et at., 1969 zoea I, counting larvae, p. 433, Fig. 1, laboratory reared. Fincham & Williamson, 1978 key to larval stages. In the following short descriptions of the key characters of the larval stages, setal counts have been omitted usually, but they are recorded in Table 1 . Description of larval stages Key characters are printed in italic type and are useful for separating stages in British species. ZOEA 1 (Fig. 1)3-3 mm (3-2-3-5 mm) Head (Figs la, b): eyes sessile. Carapace (Figs la, b): without spines, rostrum straight or downcurved at tip, tapering distally, ventral margin with minute retrorse teeth distally, equal to, or greater than, length of peduncle of antenna 1 but not reaching to end of antenna I (excluding terminal aesthetascs and setae). Antenna 1 (Fig. Ic): peduncle bearing single flagellar segment with three aesthetascs distally, usually two narrow and one wide, occasionally 1 narrow and 2 wide. Antenna 2 (Fig. Id): exopodite as a broad lamina divided into 5 short segments distally, with 9 + 2 plumose setae on inner and distal margins. Endopodite of one segment (0-67 length of exopodite), with terminal plumose seta and short spine. Mandibles (Fig. le): asymmetrical. Maxillipeds 1-3 (Figs Ih-j): with natatory exopodites. Pereiopods 1,2 (Figs Ik, 1): rudimentary, biramous. Pereiopods 3-5: absent. Abdomen (Figs 1 a, b): somite 5 with posterior margin rounded, not produced into spines, somite six continuous with telson. No trace of pleopods. Telson (Fig. Ip): fans out distally, posterior margin bears 7 + 7 plumose spines, with minute spines between four innermost spines. ZOEA 2 (Fig. 2) 3-7 mm (3-5-3-9 mm) Head (Figs 2a, b): eyes stalked. Carapace (Figs 2a, b): one dorso-medial and a pair of supra-orbital spines all bent forward with small retrorse teeth, rostrum without teeth, downturnedat end to form small hook. Antenna 1 (Fig. 2c): two peduncle segments, stylocerite forming on proximal external margin of first segment; single flagellar segment with four terminal aesthetascs, two wide and two narrow. Antenna 2 (Fig. 2d): exopodite with 4 or 5 short segments distally. Pereiopods 1 , 2 (Figs 2k, 1): developed with natatory exopodite. Pereiopods 3, 4 (Figs 2m, n): rudimentary, biramous. Pereiopod 5 (Fig. 2o): rudimentary, uniramous. Abdomen (Figs 2a, b): somite 5 with posterior margin produced into a pair of conspicuous spines, somite 6 continuous with telson. Telson (Fig. 2p): developing uropods visible beneath exoskeleton alongside telson proper; in central group of small spines, one pair longer than others. LARVAL DEVELOPMENT OF P. (P.)SERRATUS 129 Fig. 1 Zoea 1: (a) dorsal view; (b) lateral view; (c) antenna 1; (d) antenna 2; (e) mandibles; (f) maxilla 1; (g) maxilla 2; (h) maxilliped 1; (i) maxilliped 2; (j) maxilliped 3; (k) pereiopod 1; (1) pereiopod 2; (m) telson. Bar scales: a, b = 0-5 mm; c, d, h-m = 0-2 mm; g, f= 0-1 mm; e = 0-05 mm. 130 A. A. FINCHAM Fig. 2 Zoea 2: (a) dorsal view; (b) lateral view; (c) antenna 1; (d) antenna 2; (e) mandibles; (0 maxilla 1; (g) maxilla 2; (h) maxilliped 1; (i) maxilliped 2; (j) maxilliped 3; (k) pereiopod 1; (1) pereiopod 2; (m) pereiopod 3; (n) pereiopod 4; (o) pereiopod 5; (p) telson. Bar scales: a, b = 0-5 mm;c, d, h-p = 0-2 mm;g, f=0-l mm;e = 0-05 mm. LARVAL DEVELOPMENT OF P. (P.)SERRATUS 131 Fig. 3 Zoea 3: (a) dorsal view; (b) lateral view; (c) mandibles; (d) maxilla 1; (e) maxilla 2. Bar scales: a,b = 0-5 mm; c = 0-05 mm; d, e = 0-l mm. ZOEA 3 (Figs 3,4) 4-0 mm (3-7-4-3 mm) Carapace (Fig. 3a, b): two dorso- medial spines and a small fronto-lateral spine at edge of carapace beneath the eyes, former with retrorse teeth ventrally. Antenna 1 (Fig. 4a): conspicuous spine medially, stylocerite more pronounced; distal segment of peduncle bearing first segment of internal flagellum, single segment of external flagellum bearing 3 wide aesthetascs distally. Antenna 2 (Fig. 4b, c): exopodite with distal part divided into 3 short segments; endopodite of 3 segments. 132 A. A. FINCHAM Fig. 4 Zoea 3: (a) antenna 1 ; (b) antenna 2; (c) distal part of exopodite of antenna 2; (d) maxilliped 1; (e) maxilliped 2; (0 maxilliped 3; (g) pereiopod 1; (h) pereiopod 2; (i) pereiopod 3; (j) pereiopod 4 ;(k) pereiopod 5;(l)telson. Bar scales: a, b, d-I=0-2 mm; c = 0-05 mm. LARVAL DEVELOPMENT OF P. (P.) SERRA TVS 1 33 Abdomen (Figs 3a, b, 41): somite 6 divided from telson by suture. Uropod endopodite rudimentary with no marginal setae, exopodite with marginal setae. Telson (Fig. 41): narrower but still broader distally, outer pair of spines on posterior margin reduced. ZOEA 4 (Figs 5, 6) 4-5 mm (4-1-5-0 mm) Carapace (Fig. 5a, b; Fig. 6a, b): three dorso- medial spines with retrorse teeth ventrally; pair of small fronto-lateral spines at edge of carapace beneath the eyes; rostrum still downturned at end to form a small hook. Antenna 1 (Fig. 5c): single segment of external flagellum bearing 3 wide and 1 narrow aesthetascs distally. Antenna 2 (Fig. 5d): distal part of exopodite no longer divided into segments. Pereiopod 3 (Fig. 6h): developed with natatory exopodite. Pereiopod 4 (Fig. 6i): rudimentary, biramous. Pereiopod 5 (Fig. 6j): developed, uniramous. Abdomen (Figs 5a, b): endopodite and exopodite of uropod both with marginal plumose setae. Telson (Fig 6k): narrower but still broader distally; posterior margin weakly concave with 4 + 4 large spines, the 3 outer spines on the latero-distal margin reduced (outer pair sometimes absent). ZOEA 5 (Figs 7-9) 5-5 mm (5-2-5-8 mm) Carapace (Figs 7a, b): rostrum still downturned to form a small hook. Antenna 1 (Fig. 8a): rudiment of 'circular statocyst visible on first segment of peduncle. Antenna 2 (Fig. 8b): endopodite of 3 or 4 segments. Pereiopods 1 , 2 (Figs 9a, b): endopodite with internal distal margin of propodus produced slightly forward (will become fixed finger of chela). Pereiopod 4 (Fig. 9d): developed, exopod with rudimentary fringing setae. Telson (Fig. 9f): a little broader distally than proximally; spine formula as in Zoea 4 but with further reduction or even loss of small outer spines. Abdomen (Fig. 7b): somites 1-5 with rudimentary pleopods. ZOEA 6 (Figs 10-12) 5-7 mm (5-2-7-4 mm) Carapace (Figs lOa, b): rostrum weakly hooked at tip; short plumose seta in angle of anterior dor so- medial spine. Antenna 1 (Fig. 11 a): single external flagellum with four aesthetascs distally, additional group of 2 or 3 narrow aesthetascs on internal margin. Antenna 2 (Fig. lib): increase in number of segments of endopodite flagellum, approximately equal to scaphocerite in length, small spine on distal margin of peduncle segment. Maxilla 2 (Fig. 1 le): occasional increase in number of setae on basis 1 . Maxilliped 1 (Fig. 1 If): one plumose seta on proximo-lateral margin of exopod. Pereiopods 1, 2 (Figs 12a, b): endopodite with internal distal margin of propodus produced foreward to almost half length ofdactylus (excluding terminal setae). Pereiopod 4 (Fig 12d): exopodite occasionally with fringing plumose setae reduced. Abdomen (Fig. lOb): pleopods on somites 1-5 rudimentary, biramous. ZOEA 7 (Figs 13-15)6-1 mm (5-5-6-7 mm) Carapace (Figs 1 3a, b): rostrum straight or weakly hooked at tip; 2 or 3 short plumose setae in angle of anterior dorso- medial spine. Antenna 1 (Fig. 14a): two or occasionally three groups of aesthetascs on internal margin of external flagellum. Maxilla 2 (Fig. 14e): up to 6 setae on basis 2. Maxilliped 1 (Fig. 14f): 2-5 plumose setae on proximo-lateral margin of exopodite. Pereiopods 1, 2 (Figs 15 a, b): endopodite with internal distal margin produced forward to half length ofdactylus (excluding terminal setae). 134 A. A. FINCHAM Fig. 5 Zoea 4: (a) dorsal view; (b) lateral view; (c) antenna 1; (d) antenna 2; (e) mandibles; (0 maxilla l;(g) maxilla 2. Bar scales: a, b = 0-5 mm;c, d = 0-2 mm;e = 0-05 mm; f, g = 0-l mm. LARVAL DEVELOPMENT OF P. (PJSERRATUS 135 Fig. 6 Zoea 4: (a) tip of rostrum; (b) fronto-lateral corner of carapace; (c) maxilliped 1; (d) maxilliped 2; (e) maxilliped 3; (f) pereiopod 1; (g) pereiopod 2; (h) pereiopod 3; (i) pereiopod 4; (j)pereiopod 5;(k)telson. Bar scales: a, b = 0-05 mm;c-k = 0-2 mm. 136 A. A. FINCHAM Fig. 7 Zoea 5: (a) dorsal view; (b) lateral view. Bar scales: 0-5 mm. LARVAL DEVELOPMENT OF P. (P.) SERRA TVS 137 Fig. 8 Zoea 5: (a) antenna 1; (b) antenna 2; (c) mandibles; (d) maxilla 1; (e) maxilla 2; (f) maxilliped 1 ; (g) maxilliped 2; (h) maxilliped 3. Bar scales: a, b, f-h = 0-2 mm; c = 0-05 mm; d, e = 0-l mm. 138 A. A. FINCHAM Fig. 9 Zoea 5: (a) pereiopod 1 ; (b) pereiopod 2; (c) pereiopod 3; (d) pereiopod 4; (e) pereiopod 5; (f) telson. Bar scale: 0-2 mm. LARVAL DEVELOPMENT OF P. (P.)SERRATUS 139 Fig. 10 Zoea 6: (a) dorsal view; (b) lateral view. Bar scales: 0-5 mm. 140 A. A. FINCHAM Fig. 11 Zoea 6: (a) antenna 1; (b) antenna 2; (c) mandibles; (d) maxilla 1; (e) maxilla 2; (0 maxilliped 1; (g) maxilliped 2; (h) maxilliped 3. Bar scales: a, b, f-h = 0-2 mm; c=0-05 mm; d, e = 0-l mm. Pereiopod 4 (Figs 1 5d, e): exopodite occasionally with fringing plumose setae much reduced. Abdomen (Figs 13b, 15g-k): pleopods 1-5 still rudimentary, biramous with traces of terminal setae on exopodites. Telson (Figs 1 3a, 1 5 1 ): posterior margin straight or slightly convex. LARVAL DEVELOPMENT OF P. (P.)SERRATUS 141 Fig. 12 Zoea 6: (a) pereiopod 1 ; (b) pereiopod 2; (c) pereiopod 3; (d) pereiopod 4; (e) pereiopod 5; (Otelson. Bar scale: 0-2 mm. ZOEA 8 (Figs 16-1 9) 6-6 mm (5-8-7-1 mm) Maxilliped 1 (Fig. 1 8a): up to 6 plumose setae on proximo- lateral margin ofexopodite. Pereiopod 1 , 2 (Figs 1 8d, e): endopodite with internal distal margin produced forward to over half length ofdactylus (excluding terminal setae). Telson (Fig. 1 9i): posterior margin convex. 142 A. A. FINCHAM Fig. 13 Zoea 7: (a) dorsal view; (b) lateral view. Bar scales: 0-5 mm. ZOEA 9 (Figs 20-23) 7-3 mm (6-9-7-9 mm) Carapace (Fig. 20b): 3 short plumose setae in angle of anterior dorso- medial spine, 1 in angle of second dor so- medial spine. Antenna 1 (Fig. 2 la): internal flagellum of 1 or 2 segments, external flagellum of 2 segments; 3 or 4 groups of aesthetascs on internal margin of external flagellum; statocyst fully developed. Antenna 2 (Fig. 21b): increase in number of segments of endopodite flagellum, now longer than scathocerite. Maxilliped 1 (Fig. 21g): 14 to 20 setae on internal margin of basis, 5 to 9 plumose setae on proximo- lateral margin ofexopodite. LARVAL DEVELOPMENT OF P. (P.) SERRA TVS 143 Fig. 14 Zoea 7: (a) antenna 1; (b) antenna 2; (c) mandibles; (d) maxilla 1; (e) maxilla 2; (0 maxilliped 1; (g) maxilliped 2; (h) maxilliped 3. Bar scales: a, b, f-h = 0-2 mm; c=0-05 mm; d, e = 0-l mm. 144 A. A. FINCHAM Fig. 15 Zoea 7: (a) pereiopod 1 ; (b) pereiopod 2; (c) pereiopod 3; (d) pereiopod 4; (e) variant of pereiopod 4 exopod with reduced setae; (0 pereiopod 5; (g) pleopod 1 ; (h) pleopod 2; (i) pleopod 3; (j) pleopod 4; (k) pleopod 5; (1) telson. Bar scale = 0-2 mm. LARVAL DEVELOPMENT OF P. (P.)SERRATUS 145 Fig. 16 Zoea 8: (a) dorsal view; (b) lateral view. Bar scales: 0-5 mm. 146 A. A. FINCHAM Fig. 17 Zoea 8: (a) mandibles; (b) maxilla 1; (c) maxilla 2; (d) antenna 1; (e) antenna 1 - enlargement of proximal array of sensory hairs showing thread-like connections remaining in cast exoskeleton; (0 antenna 2. Bar scales: a, e = 0-05 mm; b, c = 0- 1 mm; d, f = 0-2 mm. LARVAL DEVELOPMENT OF P. (P.) SERRA TUS 147 Fig. 18 Zoea 8: (a) maxilliped 1 ; (b) maxilliped 2; (c) maxilliped 3; (d) pereiopod 1 ; (e) pereiopod 2. Bar scale: 0-2 mm. 148 A. A. FINCHAM Fig. 19 Zoea 8: (a) pereiopod 3; (b) pereiopod 4; (c) pereiopod 5; (d) pleopod 1 ; (e) pleopod 2; (0 pleopod 3; (g) pleopod 4; (h) pleopod 5; (i) telson. Bar scale: 0-2 mm. LARVAL DEVELOPMENT OF P. (P.) SERRA TVS 149 Fig. 20 Zoea 9: (a) dorsal view; (b) lateral view. Bar scales: 0-5 mm. Pereiopods 1, 2 (Figs 22c, d): endopodite with immovable finger of propodus produced forward to almost length ofdactylus (excluding terminal setae) Abdomen (Figs 20b, 23c-g): pleopods with rudimentary setae, a few fully plumose; endopodite of pleopods 2 to 5 with rudiment of appendix interna (stylamblys). Telson (Fig. 23h): further narrowing distally, posterior margin with 4 + 4 large spines (no small spines between) and with 3 reduced spines on latero-distal margin. 150 A. A. FINCHAM Fig. 21 Zoea 9: (a) antenna 1 ; (b) antenna 2; (c) antero-lateral teeth of carapace; (d) mandibles; (e) maxilla l;(f) maxilla 2; (g) maxilliped 1. Bar scales: a, b, g = 0-2 mm; c, d = 0-05 mm; e, f=0-l mm. LARVAL DEVELOPMENT OF P. (P.) SERRATUS 151 Fig. 22 Zoea 9: (a) maxilliped 2; (b) maxilliped 3; (c) pereiopod 1; (d) pereiopod 2; (e) pereiopod 3. Barscale = 0-2 mm. 152 A. A. FINCHAM Fig. 23 Zoea 9: (a) pereiopod 4; (b) pereiopod 5; (c) pleopod 1; (d) pleopod 2; (e) pleopod 3; (0 pleopod 4; (g) pleopod 5; (h) telson. Bar scale: 0-2 mm. LARVAL DEVELOPMENT OF P. (P.)SERRATUS 153 Fig. 24 Post larva 1: (a) rostrum; (b) rostrum with characters intermediate between larval and post larval phases; (c) antenna 1; (d) antenna 2; (e) mandible; (0 maxilla 1; (g) maxilla 2. Bar scales: a, b = 0-5 mm;c, d = 0-2 mm; e = 0-05 mm; f, g = 0-l mm. 154 A. A. FINCHAM Fig. 25 Post larva 1 : (a) maxilliped 1 ; (b) maxilliped 2; (c) maxilliped 3; (d) pereiopod 1 chela; (e) pereiopod 2 chela; (0 pereiopod 3; (g) pereiopod 4; (h) pereiopod 5. Bar scale: 0-2 mm. POST LARVA 1 (Figs 24-26) 7-9 mm (7-0-8-6 mm) Most specimens had metamorphosed to post larvae or intermediate stages at this moult. Meristic characters of the more advanced individuals are described here and included in Table 1. LARVAL DEVELOPMENT OF P. (P.)SERRATUS 155 Fig. 26 Post larva: (a) pleopod 1; (b) pleopod 2; (c) pleopod 3; (d) pleopod 4; (e) pleopod 5; (0 somite 5 with postero-lateral spines (plumose setae of pleopod 5 not shown); (g) uropod exopodite (plumose setae not shown); (h) telson. Bar scale: 0-2 mm. Fig. 27 Telson of palaemonid Zoea 1 . (a) Dorsal view of posterior margin. Bases of large plumose spines with row of smaller spines between, (b) Single large spine ornamented with spinules. (c) Articulation at base of large spines with circlet of small spines, (d) Ventral view of posterior margin showing rows of small spines arranged with gaps. LARVAL DEVELOPMENT OF P. (P.)SERRATUS 157 Fig. 28 Single plumose seta from natatory exopodite of pereiopod. Shaft is a differentially thickened cylinder hinged at intervals and bears two rows of thin lateral setules. (a) Seta stationary, (b) Beginning of recovery stroke, (c) End of recovery stroke. Bar scale: 0-05 mm. Carapace (Fig 24a): rostrum with 6 or 7 dorsal and 2 ventral teeth, rostral tip straight. Supra- orbital spines missing. Intermediate condition of rostrum shown in Fig. 24b. Antenna 1 (Fig. 24c): internal Jlagellum of 5 or more segments and external Jlagellum of 6 or more segments. Antenna 2 (Fig. 24d): endopodite multisegmented, at least twice as long as scaphocerite. Mandible (Fig. 24e); divided into pars incisiva and pars molaris, lacinia mobilis no longer present and palp (three jointed in adult) not yet appeared. Maxilla 2 (Fig. 240: reduction of setae on coxal endite and endopodite, increase in setae on basal endites. Maxilliped 2 (Fig. 25b): endopodite with dactylus, propodus and merus flattened. Maxilliped 3 (Fig. 25c): endopodite dactylus shortened. Pereiopods 1 , 2 (Figs 25d, e): immovable finger of propodus same length as dactylus. Pereiopods 3, 4 (Figs 25f, g): dactylus shortened. Pleopod 1 (Fig. 26a): ratio of endopodite to exopodite 1:4; endopodite bearing terminal plumose setae, exopodite fringed with long plumose setae. Pleopods 2-5 (Figs 26b-e): endopodite over half length of exopodite, both with long, marginal plumose setae, endopodite with appendix interna bearing well developed intero- distal coupling hooks. Abdomen (Fig. 260: fifth abdominal somite with posterior margin still produced into pair of lateral spines. 158 A. A. FINCHAM Telson (Fig. 26g): intermediate condition (extreme narrowing with posterior margin tapering to point not yet developed). Discussion Most of the specimens reared by Sollaud (1912) at the Marine Laboratory in Roscoff reached metamorphosis after 8 larval stages. But he found also '. . . quelques individus, en effet, peuvent presenter un stade IX supplementaire avant de se transformer. . .' He concluded, however, that the normal larval development for Palaemon serratus was eight stages (Sollaud, 1923). In the present work the differences between stages 8 and 9 were slight and confirm, therefore, the conclusion reached by Sollaud. The insertion of extra moults which probably represents an adaptation to sub-optimal conditions by prolonging larval existence is a recurrent feature of the development of Palaemoninae (Fincham, 1977, 1979). Sandifer and Smith (1979) indicated that in addition to being affected by environmental factors the tendency of individual palaemonid larvae to pass through a given number of larval stages may be inherited. They suggested also that variation in development may enhance the general advantages of an extended planktonic larval phase, a common feature of 'r' strategists. These include greater potential for dispersion and the ability to colonize new habitats quickly if favourable conditions occur. A variable planktonic existence may produce a wider spread of individuals of a given brood and average the risks of survival. At the population level Sandifer and Smith emphasize that early metamorphosis will enhance the possibility of gene flow between populations. Many environmental factors affect development including photoperiodicity. Wickins (1972) reported work on larval Palaemon serratus in which growth was improved and metamorphosis reached sooner in those reared in continuous light. Eight hours dark and 16 hours light produced improved growth compared with 8 hours light and 16 hours dark; continuous darkness produced slowest growth and development. Dalley (1979) working with Palaemon elegans concluded that greatly increased mortality during larval development in non-circadian light regimes was due to desynchronization of the circadian rhythms of metabolic processes. One feature commonly found in exuviae of the various larval stages are thin strands extending from the bases of sensory hairs (see Figs 17d, e). In a paper on the ultrastructure of the antennal sensilla of the shrimp Acetes Ball & Cowan (1977) describe dense strands of unknown composition crossing the base of their type 1 seta, which they consider uninnervated. Tracts leading from the bases of their other four types of seta contain axons. The exact nature of the strands in the exuviae of Palaemon serratus is not clear and will be examined further. Swimming: adaptations and a mechanism When palaemonid larvae first hatch they usually swim upside down and telson first. At rest the larvae tend to sink and there are several adaptations which slow the rate of descent. At either end of the body plumose setae or spines increase drag. Fringing plumose setae effectively double the area of the broad exopodite (scaphocerite) of antenna 2 at the anterior end of the body (Figs la, 2a, 3a, 5a, 7a, lOa, 13a, 16a, 20a). These antennal setae are thickened at the base (Fig. 4c) and their rigidity increases drag when the exopodites are spread. At the posterior end the telson bears stout spines which are ornamented with rows of small spines and are also plumose (Figs 27a-d). The function of the ornamentation is uncertain but might further slow the rate of sinking. Body size increases as larval development progresses and the importance of even the large spines on the telson for increasing drag, diminishes when the sixth abdominal segment develops its appendages. The exopodites of these uropods LARVAL DEVELOPMENT OF P. (P.) SERRA TVS \ 59 appear at zoea 3 (Fig. 41) and endopodites at zoea 4 (Fig. 6k) and are broad and flat and fringed with plumose setae. The spreading of these uropods slows the rate of sinking during periods when the larva is not swimming. The telson, however, retains its important function as a stabilizing hydrofoil throughout larval life and is supplied with powerful muscles that enable it to assist in orientation control. Its gradual transformation from a triangular shape at zoea 1 with a 7 + 7 spine formula (Figs 1m, 27a-d) to the narrow shape at the last larval stage with spine formula 4 + 4 and three pairs of lateral spines (Fig. 23h) accompanies the gradual development of more thoracic natatory exopodites. In the present rearing programme food is supplied to the larvae in the form of Anemia nauplii. In the wild it is likely that copepods and other small planktonic organisms form the main source of food (Sollaud used copepods in his rearing work at Roscoff). The pursuit of prey- Anemia or copepods - necessitates accurate orientation and direction control. The propulsive locomotory force is provided by the natatory exopodites developed sequentially. Zoea 1 has only three natatory exopodites - those of the maxillipeds-but biramous pereiopods are developed later and are also integrated into a regular beating pattern of the limbs. Pereiopod 5 is in fact developed by stage 4 before pereiopod 4 in Palaemon serratus but has no exopodite and is therefore not involved in larval swimming. The effective area of the propulsive exopodites is extended by the fringing plumose setae. Preliminary analysis of the swimming action from cine film shows that there is a power stroke and a recovery stroke. The morphological adaptations of these plumose setae and their role in swimming behaviour was determined following the routine examination by light microscopy of hundreds of moults during the course of the rearing programme. The shaft of the plumose setae fringing the natatory exopodites is a differentially thickened cylinder with flexible cuticular hinges at intervals along its length (Fig. 28a). The hinges only permit bending towards the unthickened side of the shaft. During the propulsive power stroke the setae remain straight with the two rows of thin, lateral setules set at an obtuse angle to the shaft, thus providing maximum surface area and purchase in the water. On the recovery stroke the flexible exopodite bends and the marginal plumose setae fold back along the many hinge lines with their thin side branches streaming out behind. This offers the least possible resistance by the exopodite to the water and repositions the limb ready to begin the next power stroke. The rhythmic beating of the six pairs of setose thoracic exopodites in the three larval stages, and swimmerets or pleopods in the post larvae of lobsters, has been analysed from cine film by Neil et al. (1976), Macmillan et al. (1976) and Laverack et al. (1976). No comparable study has been made for a caridean with regular sequential addition of limbs (in lobsters all limbs are present on hatching). The rarity of palaemonid larvae in the plankton remains an enigma especially as they are apparently so well adapted for swimming. Detailed analyses of cine film of swimming in larval palaemonids, together with plankton sampling using a static bottom net and experimental work on the periodicity of larval swimming, all of which are in progress, should shed some light on the problem. References Adensamer, T. 1898. Decapoden gesammelt auf S.M. Schiff Pola in den Jahren 1890-1894. Berichte der Commission fur Erforschung des ostlichen Mittelmeeres. XXII Zoologische Ergebnisse. XI. Denkschr. Akad. Wiss. Wien6S : 597-628. Ball, E. E. & Cowan, A. N. 1977. Ultrastructure of the antennal sensilla of Acetes (Crustacea, Decapoda, Natantia, Sergestidae). Phil Trans. R. Soc. Lond. B 277 : 429-456. Couch, R. Q. 1845. On the metamorphosis of the crustaceans, including the Decapoda, Entomostraca and Pycnogonidae. Rep. R. Cornwall polytech. Soc. 12 : 17-46. Czerniavsky, W. 1884. Crustacea Decapoda Pontica littoralia, Materialia ad Zoographiam Ponticam comparatum. II. Trans. Soc. Univ. Kharkow, 13 (suppl.) : 1-268. 160 A. A. FINCHAM Dalley, R. 1979. Effects of non-circadian light cycles on the survival and development of Palaemon elegans Rathke reared in the laboratory. In: Proc. 13th Eur. mar. Biol. Sym. 13 : 157-163 (Eds E. Naylor& R. Hartnoll. Oxford: Pergamon Press). Edwards, H. Milne 1837. Histoire naturelledes Crustaces. II. Paris. 53 1 pp. Fincham, A. A. 1977. Larval development of British prawns and shrimps (Crustacea: Decapoda: Natantia). 1. Laboratory methods and a review of Palaemon (Palaeander) elegans Rathke, 1837. Bull. Br. Mus. nat. Hist. (Zool.)31 (1) : 1-28. 1978. Larval development of British prawns and shrimps (Crustacea: Decapoda: Natantia). 2. Palaemonetes(Palaemonetes) varians (Leach, 18 14) and morphological variation. Bull. Br. Mus. nat. ///s/.(Zool.)35(2): 163-182. 1979. Larval development of British prawns and shrimps (Crustacea: Decapoda: Natantia). 3. Palaemon (Palaemon) longirostris H. Milne Edwards, 1837 and the effect of antibiotic on morphogenesis. Bull. Br. Mus. nat. Hist. (Zool.) 37 (1 ) : 1 7^46. Fincham, A. A. & Williamson, D. I. 1978. Crustacea, Decapoda: Larvae. VI Caridea, Families Palaemonidae and Processidae. Ficht. Ident. Zooplancton, 159/160: 8 pp. Forward, R. B. & Cronin, T. W. 1978. Crustacean larval phototaxis: possible functional significance. In: Proc. 12th Eur. mar. Biol. Sym. 12:253-261 (Eds D. S. McLusky & A. J. Berry. Oxford: Pergamon Press). Foxon, G. E. H. 1934. Notes on the swimming methods and habits of certain crustacean larvae. J. mar. biol. Ass. U.K. 19 : 829-849. Gurney, R. 1942. Larvae of decapod Crustacea. 306 pp. Ray Society, London. Hardy, A. C. & Bainbridge, R. 1954. Experimental observations on the vertical migrations of plankton animals. J. mar. biol. Ass. U.K. 33 : 409-448. Holthuis, L. B. 1950. The Palaemonidae collected by the Siboga and Snellius expeditions with remarks on other species. 1 . Subfamily Palaemoninae. Siboga Exped. 39a : 1-268. Keeble, F. & Gamble, F. W. 1904. The colour physiology of the higher Crustacea. Phil. Trans. R. Soc. Lond. 8196:295-388. Laverack, M. S., Macmillan, D. L. & Neil, D. M. 1976. A comparison of beating parameters in larval and post-larval locomotion systems of the lobster Homarus gammarus (L.). Phil. Trans. R. Soc. Lond. 8274:87-99. Macmillan, D. L., Neil, D. M. & Laverack, M. S. 1976. A quantitative analysis of exopodite beating in the larvae of the lobster Homarus gammarus (L.). Phil. Trans. R. Soc. Lond. B 274 : 69-85. Man, J. G. De 1915. On some European species of the genus Leander Desm., also a contribution to the fauna of Dutch waters. Tijdschr. ned. dierk. Vereen. Ser. 2, XIV : 115-1 79. Mayer, P. 1877. Zur Entwicklungsgeschichte der Dekapoden. Jena. Z. Med. Naturw. 11 : 188-269. Neil, D. M., Macmillan, D. L. & Laverack, M. S. 1976. The structure and function of thoracic exopodites in the larvae of the lobster Homarus gammarus (L.). Phil. Trans. R. Soc. Lond. B 274 : 53-68. Pennant, T. 1777. British Zoology. 4 : 136 pp. Reeve, M. R. 1969. Growth, metamorphosis and energy conversion in the larvae of the prawn, Palaemon serratus. J. mar. biol. Ass. U.K. 49 : 77-96. Risso, A. 1816. Histoire naturelle des Crustaces des environs de Nice. Paris a la libraire Greque-Latine-Allemande. 175pp. A. 1 826. Histoire naturelle des principales productions de {'Europe meridionale. 5 : 403 pp. Russell, F. S. 1925. The vertical distribution of marine macroplankton. An observation on diurnal change. /. mar. biol. Ass. U.K. 13 : 769-809. 1927. The vertical distribution of marine macroplankton. V. The distribution of animals caught in the ring-trawl in the daytime in the Plymouth area. J. mar. biol. Ass. U.K. 14 : 557-608. Sandifer, P. A. & Smith, T. I. J. 1979. Possible significance of variation in the larval development of palaemonid shrimp. J. exp. mar. Biol. Ecol. 39 : 55-64. Savage, R. E. 1926. The plankton of a herring ground. Fish. Invest. Lond. 9 : 1-35. Sharp, B. 1893. Catalogue of the crustaceans in the museum of the Academy of Natural Sciences of Philadelphia. Proc. Acad. nat. Sci. Philad. 104-127. Sollaud, E. 1912. Les metamorphoses du 'Bouquet', Leander serratus Pennant. C. R. Acad. sci. Paris 154 : 664-666. 1921. Le comportment des larves de Palaemonetes varians microgenitor Boas. Changement de signe du phototropisme apres la metamorphose. Bull. Ass. fr. Avanc. Sci. Congres de Rouen 1921:671-673. 1923. Le developpement larvaire des Palaemoninae. Bull. biol. Fr. Belg. 57 : 509-603. LARVAL DEVELOPMENT OF P. (P.) SERRATUS 161 Sui ton, A. H., Main, G. & Ronald, A. 1969. An instrument for counting the larvae of the prawn Palaemon serratus and the brine shrimp Anemia salina. Lab. Pract. 18 : 433^36. Thompson, W. V. 1836. Memoir on the metamorphosis in the Macrourae or long-tailed Crustacea, exemplified in the prawn (Palaemon serratus). Edinb. New phil. J. 21 : 221-223. Wickins, J. F. 1972. Developments in the laboratory culture of the common prawn Palaemon serratus Pennant. Fishery Invest. Lond. Series 2 27 (4) : 1-23. Williamson, H. C. 1915. Nordisches Plankton. VI. Crustacea Decapoda. Larven. Nord. Plankt. 6:315-588. Manuscript accepted for publication 1 1 June 1982. The larval development of the Angular Crab, Goneplax rhomboides (Linnaeus) (Decapoda: Brachyura) R. W. Ingle & Paul F. Clark Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD Introduction The Angular Crab, Goneplax rhomboides (Linnaeus) occurs in the Eastern Atlantic Ocean and Mediterranean Sea. It has been reported from the northern Irish Sea to as far south as the Cape region of South Africa (see Barnard, 1950 : 285; Ingle, 1980 : 109); the species occurs from the lower shore to depths of about 700 m. Capart (1951 : 1 69) discussed regional variation of this species with respect to the degree of development of the posterior pair of carapace anterio-lateral teeth and differences in shapes of the male first pleopod. He suggested two 'varieties' may exist. Specimens attributed to G. rhomboides (L.) have a very rudimentary pair of posterior teeth and are reported only from the Mediterranean Sea, coast of Mauritania and the Canary Islands whereas material assigned to G. angulata (Pennant) has been recorded from various Atlantic Ocean localities (see Manning & Holthuis, 1981 : 164). The larval stages of G. rhomboides have been described previously (see larval and post-larval references below), but these accounts are generally inadequate for use in detailed comparative studies of larval morphology. The recent rearing of G. rhomboides to third crab stage has provided sufficient material for redescribing the complete larval development of this species and an account is given here of the four zoeal and megalop stage. Materials and Methods After several unsuccessful trawling attempts, SCUBA diving was used to collect ovigerous material. On the advice of Alan Howard (MAFF) members of the BM(NH) Diving Unit searched the sandy-mud substrate to a depth of 18m off Shoalstone Point (SX937568), Brixham, Devon. An ovigerous crab was collected on 10 July 1981 and transported to the rearing laboratory of the Crustacea Section, BM(NH). The larvae were reared using methods described by Rice & Ingle (1975) and Ingle & Clark (1977), except that sea water was untreated. Drawings and measurements were made with the aid of a camera lucida. Measurements are as follows: total lengths of zoeae (T.T.) measured from tip of dorsal to tip of rostral spine and carapace length (C.L.) measured from between eyes to posterio-lateral margin of carapace (for zoeae) and from rostral tip for megalop. All material was fixed in Steedman's preservative (Steedman, 1976 : 148) and later transferred to 70% ethanol alcohol. The female and larval stages are deposited in the collections of the BM(NH), accession numbers 1981 : 540 & 1982 : 55 respectively. Descriptions Goneplax rhomboides (Linnaeus, 1 758) non Gonoplax rhomboides:-Cano, 1891, Tav. XI, figs ID (or ?E), IXd, IXe (megalops); Brachynotus sexdentatus:-Cano, 1891, Tav. XI, fig. IF (crab stage); non Gonoplax rhomboides:-Wi\\iamson, 1915, Bull. Br. Mm. not. Hist. (Zool.) 44(2): 1 63-1 77 Issued 24 February 1983 164 R. W. INGLE & P. F. CLARK Fig. 1 Goneplax rhomboides (L.): a-d lst-4th zoeae; e megalopal carapace from left lateral aspect f; megalop from dorsal aspect; g moult of megalopal abdomen slightly flattened to show setation; scale, each division = 0- 1 mm. LARVAL DEVELOPMENT OF ANGULAR CRAB Goneplax rhomboides (L.): a-d antennule of 1 st-4th zoea respectively and e of megalop; f-i antenna of lst-4th zoea and j of megalop respectively; scale = 0- 1 mm. fig. 398 (after Cano); Gonoplax angulata:- Caroli, 1927: 161 (lst-4th zoeae, megal., describ.); Gonoplax rhomboides:- Lebour, 1928 : 534, figs 4 (6-9), 5 (22-24), PI. II, fig. 6, PI. XI, fig. 10, PI. XII, figs 1-4 (lst-4th zoeae, megal., lst-4th crab); Gonoplax angulata.-Bourdi lion-Casanova, 1960 : 180, figs 57a-c (1st zoea, megal.); Goneplax rhomboides:- Rice & Williamson, 1977 : 55, fig. 29 (3rd zoea). FIRST ZOEA Dimensions: 1.1. 1-5 mm,C.L. 0-5 mm. Carapace (Fig. la): Dorsal, rostral and lateral spines present; a pair of posterio-dorsal 166 R. W. INGLE & P. F. CLARK Fig. 3 Goneplax rhomboides (L.): a-c abdomen and telson of lst-3rd zoea respectively from dorsal aspect and d-f same from lateral aspect; g, h left half of mandible of 1st and 4th zoea respectively (drawn from scanning EM photographs); scale, each division = 0-1 mm except LARVAL DEVELOPMENT OF ANGULAR CRAB 167 Fig. 4 Goneplax rhomboides (L.): a abdomen and telson of 4th zoea from dorsal aspect; b of another specimen from lateral aspect; c, d 1st maxilliped of 1st and 2nd zoea respectively; scale, each division = 0-1 mm. setules; dorso-median elevation present; posterior margin of carapace minutely serrate and with 3-4 setules. Eyes: Partly fused to carapace. Antennule (Fig. 2a): Exopod unsegmented, with 2 terminal aesthetascs and one seta. Antenna (Fig. 2f): Exopod with very minute spinules distally and with 2 median spinules and 2 setules; spinous process distally spinulate, slightly longer than exopod. 168 R. W. INGLE & P. F. CLARK Fig. 5 Goneplax rhomboides (L.): a, b 1st maxilliped endopods of 3rd and 4th zoea respectively; c, d 2nd maxillipeds of 1st and 2nd zoea and e, f 2nd maxilliped endopods of 3rd and 4th zoea respectively; g maxillule of 1 st zoea; scale = 0- 1 mm. LARVAL DEVELOPMENT OF ANGULAR CRAB 169 Mandible (Fig. 3g): Incisor and molar processes developed. Maxillule (Fig. 5g): Endopod 2 -segmented, proximal segment with one seta, distal with 2 sub-terminal and 4 terminal setae; basal endite with one seta and 4 spines on distal margin; distal and inner margins of coxal endite with a total of 6 setae. Maxilla (Fig. 7a): Scaphognathite with 4 long plumose setae and one distal stout posterior process; endopod bilobed, with 5 + 3 setae; basal endite unequally bilobed, with 4 + 5 setae; coxal endite bilobed with 4 + 4 setae. First maxilliped (Fig. 4c): Exopod incipiently 2-segmented, with 4 terminal plumose setae; endopod 5-segmented, with 3,2, 1,2,4+1 setae; margin of basis with 2, 2, 3, 3 setae. Second maxilliped (Fig. 5c): Exopod incipiently 2-segmented, with 4 terminal plumose setae; endopod 3-segmented, with 1, 1,4+1 setae; margin of basis with 4 setae. Third maxilliped'. not developed. Pereiopods: not developed. Abdomen (Figs 3a, d): 5-segmented + telson, segments 2-4 each with a pair of lateral processes decreasing in size on each respective segment; posterio-lateral margins of segments with minute denticles as shown in inset to Fig. 3d; margin of segment 2 produced and rounded, those of 3-5 with acute processes; each posterio-dorsal margin of segments 3-5 with minute denticles and of 2-5 with a pair of small setules. Telson broad, one long dorsal and one lateral spine on each fork; posterior margin concave, with 3 spines on each outer half, outermost pair longest; middle portion of telson forks invested with minute spinules. SECOND ZOEA Dimensions: T.T. 1-9-2-0 mm, C.L. 0-6-0-7 mm. Carapace (Fig. Ib): Now with 2 pairs of anterio-dorsal setules, 4-6 setules on posterior margin and a prominent dorso-median elevation; eyes free. Antennule (Fig. 2b): Exopod now with 3 terminal aesthetascs. Antenna (Fig. 2g): Exopod setules longer than in previous stage, an incipient endopod bud present. Mandible: Unchanged. Maxillule (Fig. 6a): Endopod now conspicuously stepped distally; basal endite with a prominent plumose seta on outer margin, distal and inner margins with a total of 3 setae and 5 spines; distal and inner margins of coxal endite with a total of 7 setae. Maxilla (Fig. 7b): Scaphognathite now with 12 marginal setae. First maxilliped (Fig. 4d): Exopod now with 6 terminal plumose setae. Second maxilliped (Fig. 5d): Exopod now with 7 terminal plumose setae. Third maxilliped: represented as a small bud. Pereiopods: represented as small buds. Abdomen (Figs 3b, e): Dorsal surface of 1st segment with one seta, posterio-lateral margin now slightly produced, lateral processes on segment 2 and posterio-lateral processes on 3-5 longer than in previous stage. THIRD ZOEA Dimensions: T.T. 2-8-2-9 mm, C.L. 1-1-1-2 mm. Carapace (Fig. Ic): Now with 5 pairs of anterio-dorsal setules and 7-10 setules on posterior margin. Antennule (Fig. 2c): Exopod now with 3 setules and 3 setae. Antenna (Fig. 2h): Endopod bud well developed. Mandible: Incisor sub-divided. Maxillule (Fig. 6b): Basal endite now with 3 setae on distal margin and with a total of 9 setae on distal and inner margins of coxal endite. Maxilla (Fig. 7c): Scaphognathite now with 20 setae, basal endite with 5 + 5 and coxal with 4 + 5 setae. First maxilliped (Fig. 5a): Exopod now with 8 terminal plumose setae; distal segment of endopod now with 5 + 1 setae. 170 R. W. INGLE & P. F. CLARK Fig. 6 Goneplax rhomboides (L.): a-c maxillule of 2nd-4th zoea respectively; scale = 0- 1 mm. Second maxilliped (Fig. 5e): Exopod now with 8 terminal plumose setae; distal segment of endopod with 5 + 1 setae. Third maxilliped: represented as a conspicuous biramous bud. Pereiopods: rudimentary but conspicuous, first pair incipiently chelate. Abdomen (Figs 3c, 0: Now 6-segmented + telson; a minute lateral process on segment 5 in some specimens; posterio-lateral processes on segments 3-5 longer than in previous stage; LARVAL DEVELOPMENT OF ANGULAR CRAB 171 Fig. 7 Goneplax rhomboides (L.): a, b maxilla of 1 st and 2nd zoea; c, d endopod, basal and coxal endites of maxilla of 3rd and 4th zoea respectively; scale = 0- 1 mm. dorsal surface of 1st segment now with 3 setae; rudimentary paired pleopods on segments 2-5. FOURTH ZOEA Dimensions: T.T. 3-5-3-6 mm, C.L. 1-4-1-5 mm. Carapace (Fig. Id): Now with 8 or more pairs of anterio-dorsal setules, 2 pairs at base of 172 R. W. INGLE & P. F.CLARK rostral spine and sometimes a small setule on each eye; 12-1 5 setules on posterior margin of carapace. Antennule (Fig. 2d): Exopod now with 4 terminal aesthetascs and short setae; endopod represented as an incipient bud. Antenna (Fig. 2i): Exopod now with conspicuous distal spinules; endopod bud more than half length of exopod. Mandible (Fig. 3h): Incisor and molar processes sub-divided as shown. Maxillule (Fig. 6c): Distal and inner margins of basal endite now with a total of 7 setae and 7 spines; margins of coxal endite with a total of 10 setae. Maxilla (Fig. 7d): Scaphognathite now with 31 marginal setae; margins of basal endite with 6 + 6 and coxal with 4-1-6 setae respectively. First maxilliped (Fig. 5b): Exopod now with 9 terminal plumose setae; distal segments of endopod proportionally slightly longer than in previous stage. Second maxilliped (Fig. 50: Exopod now with 10-1 1 terminal plumose setae; segments of endopod proportionally longer than in previous stage. Third maxilliped'. more conspicuous than in previous stage. Pereiopods: more developed than in previous stage. Abdomen (Figs 4a, b): Segment 6 now with minute denticles on posterio-dorsal margin and with a pair of pleopods; segments 1, 2, 3 with 5, 4, and 3 dorsal setae respectively; pleopods biramous. Medio-posterior margin of telson with 3 setae, dorsal surface with a pair of median setae. MEGALOP Dimensions: C.L. 1-8-1-9 mm. Carapace (Figs le-f): Rostrum small, slightly deflected ventrally; mesogastric region with a prominent longitudinal carina; each half of protogastric region with a prominent curved spine; cardiac and intestinal regions with carinae and broad tubercles arranged as shown in Fig. If; margin of carapace with numerous small setules. Antennule (Fig. 2e): Peduncle 3-segmented, with 2 setae on each segment; exopod 4-segmented with 0, 5, 4, 3 aesthetascs and 0, 0, 2, 2 setae respectively; endopod unsegmented, with one sub-terminal and 5 terminal setae. Antenna (Fig. 2j): Peduncle 3-segmented, with 1,1,0 setae and flagellum 7-segmented with 1 , 0, 2, 5, 0, 4, 4 setae respectively. Mandible (Fig. 9e): Molar process now reduced, palp 3-segmented, with 0, 1, 8 setae respectively. Maxillule (Fig. 8a): Endopod now reduced and unsegmented, with 2 terminal setae; margins of basal endite with a total of 1 3 setae and 8 spines; margins of coxal endite with a total of 1 5 setae/spines. Maxilla (Fig. 8b): Scaphognathite with 51 marginal setae and 4 setae on dorsal surface, posterior margin sub-truncate; endopod reduced to a sub-acute lobe with setae on outer margin; basal endite with 8 + 7 marginal setae and with additional setae on dorsal and ventral surfaces as shown; coxal endite with 6 + 9-10 setae. First maxilliped (Fig. 8c): Coxal segment with 6-7 setae, basis with 26-28 setae; endopod represented as a broad sub-acute lobe invested with 3-4 setae; exopod 2-segmented, with 3 and 5 setae respectively; epipod well developed, with 6 long setae. Second maxilliped (Fig. 8d): Coxal segment hardly differentiated from basis, with 5-6 setae, ischium to dactylus differentiated, with 0, 3, 1, 4, 5 setae respectively in addition to 4 spines on dactylar margin; exopod 2-segmented, with 2 and 4 setae respectively; 2 setae at basis-exopod junction; epipod short, with 3 distal setae. Third maxilliped (¥\g. 9a): Coxa not differentiated from basis, with 4-5 setae as shown; outer margin of ischium with 1-2 broad, acute spines and with 19-20 setae; merus to dactylus well differentiated and with 1 1-12, 5, 7, 6 setae respectively; exopod 2-segmented, with 1 and 5 setae respectively; epipod long, with numerous short setae in proximal half (circa 18) and 1 5 long medio- to distally placed setae. LARVAL DEVELOPMENT OF ANGULAR CRAB 173 Fig. 8 Goneplax rhomboides (L.): megalop-a maxillule; b maxilla; c 1st maxilliped; d 2nd maxilliped; scale = 0-1 mm. Pereiopods (Figs 9b-d, lOa, b, i): Cheliped stout, invested with numerous setae as shown in Fig. 9b; one large and one small ischial spine present; inner margin of propodal extension with 2-3 processes, inner margin of dactylus without processes. Pereiopods stout, setose as shown in Figs 9c, d & lOa, b; coxal-ischial segments of pereiopods 2-4 each with a well developed spine; dactylus of 5th pereiopod with 3 long setae on inner distal margin. 174 R. W. INGLE & P. F. CLARK Fig. 9 Goneplax rhomboides (L.): megalop - a 3rd maxilliped; b left cheliped; c 2nd pereiopod; d 3rd pereiopod; e mandible; each division of scale = 0-1 mm. Cephalothorax (Fig. lOi): Second to 4th sternites each with a prominent curved spine and a seta, first segment of sternum also with a small spine and numerous setae. Abdomen (Figs If, g & lOh): 6-segmented + telson; posterio-lateral margin of first segment sub-acute, of 2nd truncate, of 3rd-5th acutely produced and of 6th sub-truncate. Surfaces of segments invested with numerous setae distributed as shown in Fig Ig. Well developed LARVAL DEVELOPMENT OF ANGULAR CRAB 175 Fig. 10 Goneplax rhomboides (L.): megalop-a-b 4th and 5th pereiopods and c-f lst-4th pleopods respectively; g telson and left uropod from dorsal aspect; h abdomen from right lateral aspect; i sternites and coxal-ischial segments of pereiopods from left side, ventral aspect; scale, each division = 0- mm. biramous pleopods on segments 2-5, exopods with 17, 17, 16, 15 long plumose setae on lst^4th pairs (Figs lOc-f) respectively; inner distal margin of endopod of each with 3 coupling hooks. Uropods (Fig. lOg) well developed, distal segment with 7-8 long plumose setae. Telson much broader than long, dorsal surface with a pair of lateral and 2 pairs of median setules, ventral surface with 3-4 small setules. 176 R. W. INGLE & P. F. CLARK Remarks The present laboratory reared material of G. rhomboides differs in a number of features from the accounts given by Bourdil Ion-Casanova (1960) and Rice & Williamson (1977). These differences are tabulated below. Bourdillon-Casanova ZOEA! Denticles on proximal part of posterio-lateral margin of abdominal segments very pronounced. MEGALOP Disto-lateral margins of rostrum very acute. Protogastric spines of carapace stout and straight. A pair of widely spaced tubercles on meta- branchial-intestinal regions. Groups of setae on posterior region of carapace Exopod of uropod with 8-9 setae Rice & Williamson ZOEA III Antennal exopod with a single mid-point seta. Scaphognathite of maxilla with 1 8-19 setae. Endopod of 2nd maxilliped with 1,1,5 setae. ZOEAE 1-IV Exopod terminal segment of 2nd maxilliped with 4, 7,9,11 setae in respective stages. Present material ZOEA I Denticles on proximal part of posterio-lateral margin of abdominal segments very minute. MEGALOP Disto-lateral margins of rostrum not acute. Protogastric spines of carapace thin and curved. A pair of tubercles placed near to median line on cardiac region. Without groups of setae on posterior region of carapace. Exopod of uropod with 7-8 setae. ZOEA III Antennal exopod with more than one seta/spinule at mid-point. Scaphognathite of maxilla with 20 setae. Endopod of 2nd maxilliped with 1,1,6 setae. ZOEAE I-IV Exopod terminal segment of 2nd maxilliped with 4, 7, 8, 10-1 1 setae in respective stages. With the exception of Geryon tridens (Kroyer), the zoeae of Goneplax rhomboides can be distinguished from those of other known brachyrhynchs occurring in the N.E. Atlantic sea area (see Ingle, 1980) by the following combined features: (1) A pair of small but prominent dorso-lateral processes on the 4th segment of the abdomen and sometimes a minute pair on the 5th segment in the 3rd and 4th stages. (2) The antennal exopod with spinules and setae sub-terminally placed. Features separating zoeae of G. rhomboides from those of Geryon tridens were tabulated by Ingle (1979 : 229). The following amendments must now be made to this table with respect to G. rhomboides: (1) The antennal exopod-the spinous process is longer than the exopod in all stages. (2) Maxilla of ZHI-scaphognathite with a maximum of 20 setae on margin. (3) 1st maxilliped-endopod setae of ZIII, G. tridens 2, 2, 1, 2, 5+ 1 and G. rhomboides 3, 2,1,2,5+1 respectively. Acknowledgements We express our thanks to the following persons. Alan Howard, Fisheries Laboratory, MAFF, Burnham-on-Crouch, Essex, for detailed locality information that enabled us to collect material. Drs David George and Howard Platt without whose support the diving programme could not have been realized; John Tapp and Brian Maddock, ICI Marine Laboratory, Brixham, Devon, who provided facilities for keeping live crabs and helped us in many other ways. We also thank Don Claugher for providing scanning photographs that confirmed some morphological features. LARVAL DEVELOPMENT OF ANGULAR CRAB 1 77 References Barnard, K. H. 1950. Descriptive catalogue of South African Decapod Crustacea (Crabs and Shrimps). Ann. S. Afr. Mus. 38 : 1-837. Bourdillon-Casanova, L. 1960. Le meroplancton du Golfe de Marseille: Les larves de crustaces decapodes. Reel. Trav. Stn mar. Endoume30 : 1-286. Capart, A. 1951. Crustaces Decapodes, Brachyures. Result, sclent. Exped. oceanogr. belg. Eaux cot. afr. Atlant. Sud. Ill (I) : 1 1-205. Caroli, E. 1927. Sviluppo larvale della Gonoplax angulata (Pennant). Boll. Soc. Nat. Napoli 38: 161-166. Ingle, R. W. 1979. The larval and post-larval development of the brachyuran crab Geryon tridens Kroyer (Family Geryonidae) reared in the laboratory. Bull. Br. Mus. nat. Hist. (Zool.) 36 : 2 1 7-232. 1980. British Crabs, vi + 222 pp. British Museum (Natural History) & Oxford University Press, London & Oxford. & Clark, P. F. 1977. A laboratory module for rearing crab larvae. Crustaceana 32 : 220-222. Lebour, M. V. 1928. The larval stages of the Plymouth Brachyura. Proc. zool. Soc. Lond. 2 : 473-560. Manning, R. B. & Holthuis, L. B. 1981. West African Brachyuran Crabs (Crustacea: Decapoda). Smithson. Contr. Zool. 306 : i-xii, 1-379. Rice, A. L. & Ingle, R. W. 1975. The larval development of Carcinus maenas (L.) and C. mediterraneus Czerniavsky (Crustacea, Brachyura, Portunidae) reared in the laboratory. Bull. Br. Mus. nat. Hist. (Zool.) 28 : 101-1 19. & Williamson, D. I. 1977. Planktonic stages of Crustacea Malacostraca from Atlantic Seamounts. Meteor ForschErgebn. D 26 : 28-64. Steedman, H. F. (Ed.) 1976. Zooplankton fixation and preservation. In: Monographs on oceanographic methodology. 350 pp. Paris. Manuscript accepted for publication 1 1 June 1982 The larval and first crab stages of three Inachus species (Crustacea: Decapoda: Majidae); a morphological and statistical analysis Paul F. Clark Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD Introduction Several authors have acknowledged difficulties in distinguishing between congeneric brachyuran crab- larvae (see Lebour, 1928 : 546; Hartnoll, 1961 : 181; Christiansen, 1969; Rice & Ingle, \915a & 19756; Ingle, 1982). These observations were based on a limited amount of material that did not permit statistical analysis of larval characters. Rearing large numbers of crab larvae (see Ingle & Clark, 1977) provided sufficient material for this statistical study. A multivariate technique was used to examine the larvae and first crab stage of three species of spider crabs belonging to the genus Inachus. Material & Methods Berried females of Inachus dorsettensis and /. phalangium were collected by trawl from localities off Port Erin, Isle of Man, and Plymouth and /. leptochirus was trawled from Modiolus beds four miles south of Spanish Head, Isle of Man. The adult females, together with the larvae used in this study are deposited in the BM(NH). Larvae were reared using methods described by Ingle & Clark (1977), then fixed and preserved in 80% alcohol. Twenty specimens of each stage were dissected and mounted as permanent slide preparations in lignin pink/poly vinyl lactophenol. For the multivariate study 43, 142 & 178 characters were used for zoeal, megalop and first crab stages respectively. The majority of these characters are meristic, e.g. setal counts on appendages, but a few were present or absent scores. Accurate measurements of spines and carapace dimensions, as well as carapace setal counts of megalops and crab stages proved to be impracticable and were not used. Setal counts were scored for one side of the body although on occasions it was necessary to combine parts of both left and right appendages to form a complete score. The data was subjected to Principal co-ordinate analysis according to Gower (1966). This method summarizes similarities between OTUs as a 2-dimensional plot. The computation was carried out using a varian V 72 computer. Each larval stage was analysed separately to avoid major differences between stages swamping any specific variation. Results Statistical Analysis First and second principal co-ordinates were plotted for zoea II, megalops and first crab stage of each species. The zoea I stage data was not computed because only two characters were considered significant on inspection. The OTUs in zoea II (Fig. 1) can be separated into two groups, /. leptochirus and /. dorsettensis/I. phalangium whereas in both megalops (Fig. 2) and first crab stage (Fig. 3) they are clearly separated into three groups which correspond to the three species. Bull. Br. Mas. nat. Hist. (Zool)44(2): 179-190 Issued24 February 1983 179 180 +7 +6 +4 +3 e -2 o +1 o £ 'I H 06 r. "2 -3 -4 -5 -6 -7 - 6,19,2 • P. F. CLARK •^6,19,0 •"346,19,0 6,19,0 .•33,375^20,0 6,18,0 • 22,23,24,27,43,50,58 7190 •<2 7,16,0 • 36,46 7,18,0 \ 35,51,52,53,55,56,57 f -|Q Q XV 45'4ai59'.60 i1 7,16,0 \7,19,0 --7,17,0 .47,49,54 7,18,0 .87,19,2 .12,13 7,19,2 •3 7,19,2 7,20,2 .\N 7;i8,2 S.10 "1.30*7,18,0 •1,6,15,7,18,2 •4,7,16,18^18,2 -7,18,2 i i i -5 -4 -3 -2 -1 0 +1 +2 +3 +4 +5 SECOND PRINCIPAL CO-ORDINATE +6 Fig. 1 A plot of the 1st & 2nd Principal co-ordinates of zoea II. Scores of variate 1 (range 5, 6, 7), variate 1 1 (range 16, 17, 18, 19, 20) and variate 36 (range 0, 2) are plotted against their OTUs. OTUs 1-20 /. leptochirus, 21-40 /. dorsettensis, 41-60 /. phalangium. The dotted line divides the OTUs into two groups, group 1 =1. leptochirus and group 2 — 1. dorsettensis/I. phalangium. Variate 36 is the only diagnostic character separating the two groups. Note that the dotted line has no statistical significance. The zoea I stages can be divided into two groups, /. leptochirus and /. dorsettensis/I. phalangium, using the basal article of the second maxilliped and the posterio-dorsal margin of the first abdominal somite. /. leptochirus has one seta on the basis (Fig. 4b) and two on the first abdominal somite (Fig. 4c) whereas /. dorsettensis and /. phalangium have no setae at either site (Fig. 4a, d). The first zoeal stages of/, dorsettensis and /. phalangium cannot be separated on setal characters. STATISTICAL ANALYSIS OF CRAB LARVAE 181 W H H M fe +3 +2 O k +1 -1 -2 - -3 L- 1 14 • 5 17,20 • 0-15 12 *f 13« 16 35 31 32 • •" 29 51 53 • ^ 27 28 43 • 59* 41 48 47* 56 • 44 24 37 36.3_3.._»30 37 • 55 34 •23*38 21* • 22 50 52 46* 54 • I I I -.4 -3 -2 -1 0 +1 +2 SECOND PRINCIPAL CO-ORDINATE + 3 +4 Fig. 2 A plot of the 1 st & 2nd Principal co-ordinates of megalops using 68 variates. OTUs 1-20 /. leptochirus, 21-40 /. dorsettensis, 41-60 /. phalangium. These OTUs fall into 3 distinct groups which correspond to the three British Inachus species. The second zoeal stages can also be split into the same two groups (Fig. 1). The three characters showing variation were the number of terminal aesthetascs on the antennule, the numbers of setae on the margin of the maxillary endopod and on the posterio-dorsal margin of the first abdominal somite. The scores of these three characters are shown respectively on Fig. 1 in bold type, adjacent to their respective OTUs. Separation of the two groups shown by the dotted line is determined only by one character, the number of posterio-dorsal marginal setae on the first abdominal somite. /. leptochirus has 2 setae (Fig. 4c) whereas /. dorsettensis and /. phalangium have none (Fig. 4d). The megalops can be divided into three groups which correspond to the three species using only 68 out of the original 142 characters (Fig. 2). Group separation remains constant how- ever, if only nine characters are used. By using combinations of the means of these nine characters it seems possible to separate the megalops of the three species. Nevertheless, their overlapping distribution (Table 2) makes separation very difficult in practice as no single character separates all three species. For example, OTU 21 (I. dorsettensis) is grouped with OTUs 52 and 53 (I. phalangium) on its overall similarity as they have identical scores for all nine characters. Overlapping ranges of variation in numbers of setae makes it impossible to differentiate all three species with absolute confidence at the 182 P. F. CLARK W H +2 p ? +1 o Pu H -1 n fe "2 -3 -4 • 12* 19 4« .. »ir • 3 • 13 3 14 53* 57 "44 58* 28.38 22* «37 oc, *26 29 21. * 23.. -* "n • •31 25«« -4 -3 -2 -1 + 1 +4 SECOND PRINCIPAL CO-ORDINATE Fig. 3 A plot of the 1 st & 2nd Principal co-ordinates of the first crab stages using 1 38 variates. OTUs 1-20 /. leptochirus, 21-40 /. dorsettensis, 41-60 /. phalangium. These OTUs fall into 3 distinct groups which correspond to the three British Inachus species. megalop stage. Only the number of setae on the proximal exopod segment of the antennule (Figs. 4e, f) displays no intraspecific variability and serves as a diagnostic character separating /. leptochirus from /. dorsettensis/I. phalangium. The number of spines on the merus of the first peraeopd is also a relatively good character separating /. leptochirus from the other two species, but this is a particularly difficult character to observe because of the thickness of the merus. Differentiation of the first crab stage OTUs (Fig. 3) was achieved using 1 38 characters from the original 178, but clustering of the OTUs corresponding to the three Inachus species does not alter when the number of characters is reduced to 21 (Fig. 5). These 21 characters are listed in Table 3. As with the megalops, separation of the three species is marked when the means of the variates (Table 4) are used, but again the distributions show considerable overlap. In STATISTICAL ANALYSIS OF CRAB LARVAE 183 Fig. 4 2nd maxilliped, zoea I (a) /. dorsettensis & I. phalangium (b) /. leptochirus; abdomen of zoea I & II (c) /. leptochirus (d) /. dorsettensis & I. phalangium; antennule of megalop (e) /. leptochirus (f) /. dorsettensis & /. phalangium. 184 P.F.CLARK Table 1 A list of characters that may separate the megalops of the three Inachm species Variate no. Characters 4 7 44 48 62 67 81 95 109 number of setae on proximal exopod segment of antennule number of setae on first segment of antenna number of setae on merus of 3rd maxilliped number of setae on epipodite of 3rd maxilliped number of spines on merus of 1st peraeopod number of setae on propodus of 2nd peraeopod number of setae on propodus of 3rd peraeopod number of setae on propodus of 4th peraeopod number of setae on propodus of 5th peraeopod Table 2 Studying the means of each character from Table 1 , the megalops in theory are separable using combinations of characters. However, if the distribution of each character is tabulated only variate 4 is a good diagnostic character, but this only separates 7. leptochirus from /. dorsettensis/I. phalangium (see Figs. 4e, 0- (L = 7. leptochirus, D = I. dorsettensis & P = 7. phalangium) distribution of variate 4 1 2 L 0 20 D 20 0 P 20 0 variate 4 separates L from D & P distribution of variate 7 0 1 L 0 20 D 2 18 P 15 5 variate 7 separates P from D & L distribution of variate 44 4 5 L 1 19 D 18 2 P 16 4 variate 44 separates L from D & P distribution of variate 48 0 1 2 LOO 7 13 D 1 9 8 2 P 0 5 10 5 variate 48 separates L from D & P distribution of variate 62 2 3 L 00 D 0 20 P 415 variate 62 separates L from D & P 20 0 1 mean 2 1 1 mean 1 1 0 mean 5 4 4 mean 3 2 2 mean 4 3 3 distribution of variate 67 16 17 18 mean L 3 17 0 17 D 19 1 0 16 P 0 19 1 17 variate 67 separates D from L & P distribution of variate 81 15 16 17 mean L 0 2 18 17 D 1 19 0 16 P 0 3 17 17 Variate 8 1 separates D from L & P distribution of variate 95 15 16 17 mean L 0 6 14 17 D 4 16 0 16 P 1 10 9 16 variate 95 separates L from D & P distribution of variate 109 14 15 16 mean L 1 2 17 16 D 0 20 0 15 P 1 18 1 15 variate 1 09 separates L from D & P Note that the means have been rounded up to the nearest whole number. STATISTICAL ANALYSIS OF CRAB LARVAE 185 Table 3 List of characters that may be used to separate the 1 st crab stages Variate no. Characters 6 aesthetascs on 2nd exopod segment of antennule 9 setae on endopod of antennule 1 3 number of setae on 3rd segment of antenna 14 number of spines on 1st segment of antenna 2 1 number of setae on distal segment of mandibular palp 45 number of setae on basis of 2nd maxilliped 57 number of setae on coxa of 3rd maxilliped 94 number of setae on basis of 2nd peraeopod 99 number of spines on merus of 2nd peraeopod 1 00 number of spines on ischium of 2nd peraeopod 1 14 number of setae on ischium of 3rd peraeopod 1 1 5 number of setae on basis of 3rd peraeopod 1 20 number of spines on merus of 3rd peraeopod 1 2 1 number of spines on ischium of 3rd peraeopod 1 35 number of setae on ischium of 4th peraeopod 1 36 number of setae on basis of 4th peraeopod 141 number of spines on merus of 4th peraeopod 146 number of hooks on propodus of 4th peraeopod 1 56 number of setae on ischium of 5th peraeopod 1 57 number of setae on basis of 5th peraeopod 1 67 number of hooks on propodus of 5th peraeopod practice, only a combination of characters can be used to distinguish between the species at first crab stage. Morphology The general morphology of/, dorsettensis was described and illustrated by Ingle (1977). Most of the setal counts fall within the variation recorded during the present study. This indicates little or no temporal variation. Some of the discrepancies may be due to the difficulty of classifying and objectively defining elements, as between a seta and a spine, when the structures grade one into the other (Gurney, 1931 : 38). However, some disparity between Ingle's study and the present work could not be accounted for. Discussion Williamson (1965 : 390) listed the presence of a seta on the outer margin of the maxillule basal endite as one often characters for separating brachyuran larvae from anomuran larvae. In previous descriptions of zoea II in majids this character is shown as present, for example, Ingle (1977) records this seta as present in zoae II and megalops of Inachus reared from Plymouth material — this was confirmed by re-examining Ingle's material and by rearing fresh material from the Plymouth area. In this study the seta was absent from zoea II of/. dorsettensis reared from the Isle of Man and from all three megalops. Lebour* (1928) suggested that larvae of the three Inachus species could be separated on size, chromatophore patterns and length of dorsal spines, but none of these claims could be verified. Only the megalops and first crab stage of/, leptochirus in the present study proved to be larger than those of the other two species. Larval inachinids have apomorphic zoeal characters which were listed by Rice (1980 : 307), to which can now be added the absence of *Lebour's material is no longer extant; Ingle, pers. comm. 186 P. F. CLARK a c '-' 00 <U || .S."SflL a> oo vo vo £ 3 <L> & oj .22 -O .5 £•" | — — o o *1 1 c c c c eri 03 OO^ ~2 S — 0 o 2 ^ o o D (N — •* <N S — o o OJ f^1 O •—" "55 •" . £ £ £ £ .0 •— *** Q 2 £ II Q Q &\ ^f C1 ^^ kj < Q d*j 1/5 2 a. r\ Cu \h *• Ov CU § c * J3 J5 ^ £ o ^^ ff ^00*000 g Ov C O\ £ g "*• o Si «fc -C -SI •2 Q tt •2 ^- -2 •2 i-J <-> -C ^j o o ^ oj cl C § — O oo en J > i — m o O t/' V^ 0) ^" ^^ ^*. ^ "^ "" <S ^ -s-°i a <N o — • oo $ — r \ -4-1 ^ 2 H .1 II c •2 a 2 a u C/5 03 s: .0 vo o "n r- S •S "" — u *S t/5 c 2 c O — fsl ON —H oc Q •— » >M u ••<• a g a 2 03 a R a O — O ^ OO QJ 3 0 £ S~ •o ^O p^. ^2 ^ ^o ON •^ ^5 o -S . *2 _jj C IT) W (TV V S ™" Or 't- o S; IU t^ "^ O >n m w • 2 & .^ <U ^? .22 u. .22 to ^ .2 "Q 03 "S 'Jg "S «3 ^ .2 OJ *^ O •r" ||| O 0 <N i— i r~ 03 — > ^^ ^^ t*^ f^^ o3 |M o o — o 0 O m ON O 03 — <N > O O ""> m 03 "^ JQ cu JQa. J Q cu JQfl. JQo. "" > § O MT* *•* j Q Q C o BO Q c • _i C^ o Im- -S C Os ^ djK C <% n~ °O 03 °° •^ oj f> <N m Cu ~~< ^ _«. ^ * (U ^T f** f*i Q^ C &l ~~> 03 , ^* fN OJ <N — ~ — " « BB (M 6A <D (U *~ ^J C .2 cu E Si £ Cu •5- £ ^> £ c ^ .2 o -2 S £ o Si £ c •2 o C3 " p^ o a o <i- ^ £ **• tt •£ J2 « 5. m oo O o«t: § TJ- — 0 VO Q § Tj- OO ON vO , .§ ^ ^ VO O J 00 £ Jj 5* 1/5 "d ^ s ° U "^ g •£ o o >. •2 <N <N r^i U o ^ •2 ~ .O ro ON O Tt 2 -2 m «N ON m 2 .0 — 0 Tf ON 2 -a c <u ^ 3 O C 5 « "5 ° .a a ^ u a >< — 1 S 3 0. J .^ <u >*o D. OJ 1/2 *> _ _ w 3 Q. ! o H ^-ooo O (« •55 m — t — oo ai S CN| 0 O O rr> ^ <N ' .^ <N O <N — 00 | 0 0 0 - - ^ "c *- "^ Ss u ^ <L) "S OJ "^ aj •^ o _e •*; CO .2 .2 .2 .2 •g o-£ c, JQ 'C Cu > JQD. § *c jQo. 2 'C j Q o_ > STATISTICAL ANALYSIS OF CRAB LARVAE 187 f mean — o o cu Q c 1 PO CN CO CU o o — ' °o! c cu *n ^^ *n e a. C CU <N — ' (N E cu c CU **} <N <N E tx -J ^5 cu •^ e ^h 6 K-i 6 ^ p E •Si £ •Si & •Si vOr^O<N ^g ^^ . ^^ *— ~. <^ ir fS) i*i ^j i": Q •Si 0 i: •2 •2 Q •2 Q 1 Q •2 Q 1"" r- <N 0 ft §-* r^O- ft <-> 1 C/5 cu 4-1 S CU 1 C/5 CU ^ 1 ^ 2 ^ 2 "o1 8 %> 8 R •2 a cu |^ cd VO O OO O. •1 10 t^ ^— t^ Q- "^ C/5 |-o2« | |^g°^ 03 a cu C/} 3 ^ 3 ^ 3 VO rv f*^ 3 7g £5 cu .^5 cu •^ CU ,***> CU *5 cu ^ .2 "3 "5 ~5 .2 "3 "«j ^ o3 *i_ t- •g o m oo o <a <N "" ^° 5 — ' O ON — J3 — > O O — O ea <N O O <•*•> > -) Q cu QQ- Qcu Q cu J - o — — ON — oo O 3 -c> o — o — cu "08 Q. C j ^ O ct (N ON O O ™ ^ $ 2 a --oo£ -oo — oo — O 05 a 3 & 7$ O C O tN ON O r^J "3 ° eS cu p O .« — — a 2 -s. rS «n ^^o-^ 2 So i£ §_ Qou Qeu Qo- Qcu 188 P. F. CLARK Q 05 O I O O 05 (X, H CO 05 +7 +6 +5 +4 +3 +2 +1 -1 -2 -3 -4 -5 -6 -7 L • 25 33 24 31. • 23 38* • 29 •28 36 57 .58.48 •44 • ' 51 •53 •47 43 54« 13, I I • 5 14* 9* 4 A 16 «• ,10,11,18,20 -6 -5 -4 -3 -2 -1 0 +1 +2 +3 SECOND PRINCIPAL CO-ORDINATE +4 + 5 Fig. 5 A plot of the 1st and 2nd Principal co-ordinates of first crab stage using 2 1 variates. OTUs 1-20 7. leptochirus, 21-40 /. dorsettensis, 41-60 /. phalangium. Although the number of variates is reduced from 138 to 21, the OTUs still fall into 3 distinct groups which correspond to the 3 British Inachus species. The grouping of the OTUs is similar to that in Fig. 3 and therefore illustrates that the 21 characters selected contribute to the separation of the 3 groups. Note that the groups /. leptochirus and /. dorsettensis have changed positions when compared with Fig 3; this has no significance in the analysis. STATISTICAL ANALYSIS OF CRAB LARVAE Genus INACHUS 189 Genus MACROPODIA group 1 I. leptochirus I. thoracicus group 2 I. dorsettensis I. phalangium M. tenuirostris M. rostrata 2 setae present on first abdominal somite First abdominal somite without setae. Zoea I without a seta on basis of 2nd maxilliped Distal endopod segment of 2nd maxilliped with 3 terminal setae. Distal endopod segment of 2nd maxilliped with h setae. 1 seta present on basis of 2nd maxilliped in zoea I and absent in zoea II. Zoea II with mandible palp and antennule endopod absent. Fig. 6 Cladogram of known Inachus & Macropodia larval descriptions. a mandibular palp and endopod bud on the antennule of zoea II. Similarly, when compared with other majid larva characters the loss of paired dorsal setae on the first abdominal somite and the absence of setae on the basis of the 2nd maxilliped in /. dorsettensis and /. phalangium, can be considered as derived traits. The present study failed to reveal characters which separate the larvae of/, dorsettensis from /. phalangium, but demonstrated that the larvae of/, leptochirus can be easily recognized. Adult males of/, leptochirus share one important feature with two other species of Inachus (i.e. /. thoracicus & I. aquiarii) in having a sternal callosity, a character that is absent in males of/, dorsettensis, I. phalangium and /. communissimus. Such a separation of Inachus species into two groups, those with and those without a sternal callosity, is supported by the present study. Heegaard (1963) studied the zoeae of/, thoracicus and clearly figures two setae on the first abdominal somite (p. 475, Fig. 83), but not a seta on the basis of the 2nd maxilliped (p. 475, Fig. 82). Unfortunately Heegaard's material is no longer extant. Re-examination of /. thoracicus zoeae may well show that they are inseparable from /. leptochirus, adding support to the suggestion that there are two natural groups in the genus Inachus. Present larval evidence supports the view that Inachus and Macropodia are the most derived of all majids since they show the greatest reduction in numbers of setae; considered by Rice (1980) to be the derived condition. A suggested phylogeny of well documented larvae from the genera Inachus and Macropodia is shown in Fig. 6. Setal studies of other brachyuran genera have shown that the larvae of species accepted as 190 P. F. CLARK closely related are not usually separable on quantitative characters. Therefore meristic setal incongruities within genera, as shown here for Inachus, may be the only morphological evidence of phylogenetic non-homogeniety. This project formed part of an M.Sc. degree in Modern Taxonomy. All relevant data and larval figures were deposited in the Crustacea Section, BM(NH) and the Library of the Polytechnic of Central London. Acknowledgements I wish to thank Drs Roger Lincoln, Ray Ingle and Geoff Boxshall, Crustacea Section BM(NH), for their help and critical comments on earlier drafts of this paper. For help with collection of ovigerous crabs, I thank Mr Tony Mattacola, Plymouth Marine Laboratory, the crews of the research vessels, Sarsia, Sepia & Squilla (Plymouth Marine Laboratory) and Cuma & Silver Spray (Port Erin, Isle of Man) and Drs D. I. Williamson & Richard Hartnoll (Port Erin Marine Station, University of Liverpool). Miss Joan Ellis, Crustacea Section, kindly sorted through large quantities of Modiolus, and Dr M. Hills & Miss Kay Shaw, Biometrics Section, gave invaluable statistical advice. References Christiansen, M. E. 1969. Marine invertebrates of Scandinavia. No. 2. Crustacea, Decapoda, Brachyura. Universitetsforlaget, Oslo pp. 1-143. Oslo. Clark, P. F. 1980. British Spider Crabs of the genus Inachus; a morphological study of larval development. M.Sc. Modern Taxonomy (C.N.A.A.) Thesis. Polytechnic of Central London/City of London Polytechnic. Gower, J. C. 1966. Some distance properties of latent root and vector methods used in multivariate analysis. Biometrika 53 (3-4) : 325-358. Gurney, R. 1931. British Fresh- Water Copepoda. Vol. 1, 239 pp, Ray Society, London. Hartnoll, R. G. 1961. A re-examination of the Spider Crab, Eurynome Leach from British waters. Crustaceana2(3) : 171-182. Heegaard, P. 1963. Decapod larvae from the Gulf of Napoli, hatched in captivity. Vidensk. Meddr dansk. nalurh. Foren. 125 : 449-493. Ingle, R. W. 1977. The larval and post-larval development of the Scorpion Spider Crab, Inachus dorsettensis (Pennant) (Family: Majidae) reared in the laboratory. Bull. Br. Mus. nat. Hist. (Zool.) 30 (9) : 329-348. 1982. Larval and post larval development of the slender- legged Spider Crab, Macropodia rostrata (Linnaeus) (Oxyrhyncha: Majidae: Inachinae), reared in the laboratory. Bull. Br. Mus. nat. Hist. (Zool.) 42 (3) : 207-225. Ingle, R. W. & Clark, P. F. 1977. A laboratory Module for rearing crab larvae. Crustaceana 32 (2): 220-222. Lebour, M. V. 1928. The larval stages of the Plymouth Brachyura. Proc. zool. Soc. Lond. 2 : 473-560. Rice, A. L. 1980. Crab zoeal morphology and its bearing on the classification of the Brachyura. Trans. zool. Soc. Lond. 35 : 271-424. Rice, A. L. & Ingle, R. W. 1975a. The larval development of Carcinus maenas (L.) and C. mediterraneus Czerniavsky (Crustacea, Brachyura, Portunidae) reared in the laboratory. Bull. Br. Mus. nat. Hist. (Zool.) 28 (3) : 101-1 19. 19756. A comparative study of larval morphology of the British Portunid crabs Macropipus puber(L.) and M. holstatus (Fabricius), with a discussion of generic and sub-familial larval characters within the Portunidae. Bull. Br. Mus. nat. Hist. (Zool.) 28 (4) : 1 2 1-1 5 1 . Williamson, D. I. 1965. Some larval stages o"f three Australian crabs belonging to the families Homolidae and Raninidae, and observations on the affinities of these families (Crustacea: Decapoda). Aust. J. mar. Freshw. Res. 16 : 369-398. Manuscript accepted for publication 18 June 1982. British Museum (Natural History) British Marine Amphipoda: Gammaridea by R. J. Lincoln 658pp 2,300 figures 4to hard bound ISBN 0 565 00818 £50.00 Amphipods are both numerous and diverse in numbers of genera and species in British coastal waters, but in the absence of any form of modern systematic synopsis or key this group of crustaceans has acquired the reputation of being notoriously difficult to identify. This monograph, which is the first comprehensive and illustrated text on British gammaridean amphipods to be published in more than a century, should go a long way towards solving the problem. The systematic section of the book contains descriptions and figures of all 271 species of marine and brackish water amphipods, in 123 genera and 36 families, recorded from British coasts and the adjacent continental shelf to a depth of 200 metres. Keys are provided at all levels, as well as relevant synonymies and diagnoses of genera and families. The text is illustrated with about 2,300 separate figures which have been drawn by the author from Museum and other material, in many cases with reference to type specimens. The work has been carefully edited to bring corresponding descriptions, keys and figures into close proximity within the text. The systematic section is supported by chapters dealing with morphology, systematics, geographical distribution, biology and ecology, the latter being presented in the form of an annotated subject index of research literature. Finally, there is an extensive bibliography of about 1,200 references that includes most of the British marine amphipod literature published to date. Publications Sales, British Museum (Natural History), Cromwell Road, London SW7 5BD, England. Titles to be published in Volume 44 Observations on the systematics of the genus Difflugia in Britain (Rhizopoda, Protozoa). By Colin C. Ogden Miscellanea A review of the Euplotidae (Hypotrichida, Ciliophora). By Colin Curds & Irene C. H. Wu Osteology, genitalia and relationships of the Acanthodactylus (Reptilia : Lacertidae). By E. N. Arnold The Opthalmotilapia assemblage of cichlid fishes reconsidered. By Peter Humphrey Greenwood Morphological studies on some Difflugiidae from Yugoslavia (Rhizopoda, Protozoa). By Colin G. Ogden & Andjelija Zivkovic Printed by Henry Ling Ltd, Dorchester Bulletin of the British Museum (Natural History) A review of the Euplotidae (Hypotrichida, Ciliophora) Zoology series Vol 44 No 3 31 March 1983 The Bulletin of the British Museum (Natural History), instituted in 1949, is issued in four scientific series, Botany, Entomology, Geology (incorporating Mineralogy) and Zoology, and an Historical series. Papers in the Bulletin are primarily the results of research carried out on the unique and ever-growing collections of the Museum, both by the scientific staff of the Museum and by specialists from elsewhere who make use of the Museum's resources. Many of the papers are works of reference that will remain indispensable for years to come. Parts are published at irregular intervals as they become ready, each is complete in itself, available separately, and individually priced. Volumes contain about 300 pages and several volumes may appear within a calendar year. Subscriptions may be placed for one or more of the series on either an Annual or Per Volume basis. Prices vary according to the contents of the individual parts. Orders and enquiries should be sent to: Publications Sales, British Museum (Natural History), Cromwell Road, London SW7 5BD, England. World List abbreviation: Bull Br. Mus. not. Hist. (Zool.) Trustees of the British Museum (Natural History), 1982 The Zoology Series is edited in the Museum's Department of Zoology Keeper of Zoology : Dr J. G. Sheals Editor of Bulletin : Dr C. R. Curds Assistant Editor : Mr C. G. Ogden ISSN 0007-1498 Zoology series Vol 44 No 3 pp 191-247 British Museum (Natural History) Cromwell Road London SW7 5BD Issued 31 March 1983 A review of the Euplotidae (Hypotrichida, Ciliophora) Colin R. Curds & Irene C. H. Wu Zoology Department, British Museum (Natural History), Cromwell Road, London SW7 5BD Contents Introduction Key to Genera . Genus Discocephalus Genus Diophrys Genus Uronychia . Genus Certesia . Genus Gastrocirrhus Genus Euplotaspis . Genus Euplotidium . Genus Paraeuplotes . Genus Swedmarkia . Genus Gruberella Genus Cyatharoides. References . Index . 191 192 193 197 215 227 228 232 234 239 240 242 243 244 247 Introduction Guides to the species of two genera of Euplotid ciliates, Euplotes Ehrenberg in Hemprich and Ehrenberg, 1831 and Aspidisca Ehrenberg, 1830, have been published in recent years (Curds, 1975; Wu & Curds, 1979). The other genera in the family Euplotidae Ehrenberg, 1838 contain fewer species but there are still identification problems in some. The present work is intended to aid the specific identification of the remaining nine genera which Borror (1972) grouped together into the Euplotidae, another more recently described genus and one other addition. Although four of these genera only contain single species it was thought worthwhile to include them for completeness. The genera included here are in chronological order of authority. Discocephalus Ehrenberg in Hemprich and Ehrenberg, 1828; Diophrys Dujardin, 1841; Uronychia Stein, 1859; Certesia Fabre-Domergue, 1885; Gastrocirrhus Lepsi, 1928; Euplotaspis Chatton and Seguela, 1936; Euplotidium Noland, 1937; Paraeuplotes Wichterman, 1942; Swedmarkia Dragesco, 1954; Gruberella Corliss, 1960 and Cyatharoides Tuffrau, 1975. Members of the Euplotidae are hypotrichs with the characteristically prominent adoral zone of membranelles (AZM) arranged at the anterior left of the ventral surface bordering a wide peristome. In certain genera the AZM may continue over the apical end of the body onto the dorsal surface. Unfortunately there is no set of characters which will include all of Borror's (1972) genera into the family. This could well indicate that it is not a natural family. The cirri on the ventral surface are arranged in distinct groups but they are not the only hypotrichs to have this feature. For example, the Oxytrichidae Ehrenberg, 1838 also have grouped cirri, and Borror (1972) distinguished them from the Euplotidae by their possession of only a few left marginal and no right marginal cirri, even so there are several exceptions to Bull. Br. Mus. nat. Hist. (Zool.)44(3): 191-247 Issued 31 March 1983 191 192 C. R. CURDS & I.C. H. WU this rule. Furthermore, while right caudal cirri are present in Diophrys, Discocephalus, Euplotes and Uronychia, they are absent in others. However, transverse cirri are present in all but one Euplotid genus. With this state of affairs, perhaps it is not surprising that there is some disagreement in the literature as to what constitutes the family Euplotidae. Borror (1972) included Aspidisca in the family but Stein (1859a), Biitschli (1889), Kahl (1932), Faure-Fremiet (1961) and Corliss (1961, 1977, 1979) all maintain it in a separate family the Aspidiscidae Ehrenberg, 1838. Corliss (1979) included four genera in the family Aspidiscidae; Aspidisca, Euplotaspis, Onychaspis Stein, 1859 and Paraeuplotes (as an incertae sedis). The genus Onychaspis differs from Aspidisca only by the former's possession of a larger number of transverse cirri and most authors consider it to be a synonym of Aspidisca (Borror, 1972; Wu and Curds, 1979). Indeed, Corliss (1979) indicated this possibility in his classification. One of the features of the Aspidiscidae is the great reduction of oral membranelles, however this description would not fit the AZM of Euplotaspis or Paraeuplotes. Corliss (1979) also placed three of the genera being considered here (Cirrhogaster Ozaki and Yagui, 1941; Euplotidium and Gastrocirrhus) into the family Gastrocirrhidae Faure-Fremiet, 1961 . Here the single species genus Cirrhogaster is regarded as a member of the genus Gastrocirrhus as it only differs slightly in cirral number. Borror (1972) included Gastrocirrhus in the Euplotidae but noted that its position in that family was provisional. It is clear from this brief synopsis that the position of these genera within three or a single family group is still in a state of flux and to a large extent a matter of conjecture. It is not the purpose of the present paper to attempt to assign the genera to any old, current or new classification scheme; more data, particularly concerning their comparative morphogenesis, are required before anything useful can be suggested. The aim here is to aid the marine ecologist and protozoologist to identify the species of those genera which conveniently fall within the single family Euplotidae. Key to Genera 1 AZM conspicuous, in single anterior part 2 AZM inconspicuous, in 2 parts ASPIDISCA (see Wu& Curds, 1979) 2 Without frontoventral cirri, caudals never extremely large . . . GRUBERELLA(p.242) With frontoventral cirri (when frontoventrals reduced and inconspicuous then caudals usually very large) 3 With caudal cirri 4 Without caudal cirri 11 4 With marginal cirri, caudals sometimes very large 5 Without marginals, caudals present but never very large 5 Caudals very large and prominent 6 Caudals weak EUPLOTES (see Curds, 1975) 6 5- 10 conspicuous frontoventral cirri present, moves forwards . . DIOPHRYS (p. 197) 3 inconspicuous cirri present, moves backwards URONYCHIA(p.2l5) 1 Elongate with discoid 'head' region DISCOCEPHALUS (p. 193) Ovoid to elongate, when elongate never with discoid 'head' region 8 8 Ovoid, dorsoventrally flattened 9 Elongate, rounded in section, often cup-shaped with funnel-shaped peristome opening apically and ventrally 10 9 Cirri mainly in 2 rows, found on coral PARAEUPLOTES (p. 239) Cirri in well-defined groups, found in sea-squirts EUPLOTASPIS (p. 232) 10 With 5-6 transverse cirri EUPLOTIDIUM (p. 234) Without transverse cirri GASTROCIRRHUS (p. 228) 11 Without marginal cirri, rounded in section EUPLOTIDIUM (p. 234) With marginal cirri, dorsoventrally flattened 12 1 2 Marginal cirri on both right and left sides, confluent posteriorly . SWEDMARKIA (p. 240) Marginal cirri on either right or left sides 13 13 Marginal cirri on left, not planktonic CERTESIA(p.221) Marginal cirri on right, planktonic CYATHAROIDES(p.243) REVIEW OF EUPLOTIDAE 193 Genus DISCOCEPHALUS Ehrenberg, 1 828 Introduction The genus Discocephalus was erected by Ehrenberg in Hemprich and Ehrenberg (1828) and although his description and illustration of the type species D. rotatorius were crude, it was clear that the organism had a distinctive discoid 'head' formed by a constriction at the anterior end of the elongate oval body. Butschli (1889) expressed some doubt concerning the observations of Ehrenberg (1831) but it was not until Kahl (1932), that Discocephalus was adequately described. The latter description concerned an organism which Kahl (1932) considered to be D. rotatorius Ehrenberg and of which he thought Polycoccon octangularis Sauerbrey, 1928 to be a junior synonym. Later, however, Dragesco (1960) isolated an organism from Roscoff which although identical to that described by Kahl (1932) was different in several respects from D. rotatorius Ehrenberg. Dragesco (1960) therefore named the species found at RoscoffZ). ehrenbergi and designated D. rotatorius Kahl to be its junior synonym. However, Dragesco (1960) agreed that Polycoccon octangularis Sauerbrey was a synonym of D. rotatorius Ehrenberg. In addition to the two species mentioned above two others, D. grandis Dragesco, 1954 and D. minimus Dragesco, 1968, have been described. There is a well developed AZM in all four of the above species which borders the small ventral peristome on the left of the discoid 'head'. In one species, D. ehrenbergi, there are 5-7 large membranelle-like structures lying along the right border of the peristome which Dragesco (1968) called 'pre-membranelles'. This character enables the diagnosis and separation of D. ehrenbergi Dragesco from D. rotatorius Ehrenberg which lacks these 'membranelles'. The cirral patterns on the ventral surface of Discocephalus differ greatly from those of Euplotes and as their morphogenesis is yet to be published fully it is difficult to interpret them adequately. Furthermore as the cirri vary considerably from species to species, it is possible that Discocephalus is really a polyphyletic group. The present confusion in different terms used for the same cirri by different authors can be illustrated by reference to 'marginal' cirri. In D. rotatorius and D. ehrenbergi there are two 'marginal' cirri on the left body edge just below the peristome. However, in D. grandis, Dragesco (1954) refers to the presence of three rows of 'marginal' cirri which is more characteristic of members of the Oxytrichidae rather than the Euplotidae. Furthermore, in D. minimus there is one row of cirri on the right body edge called ventral cirri and one row on the left edge called 'marginal' cirri. Until further morphogenetic information becomes available the present authors prefer to follow in part the system used by Hartwig and Parker (1977) which distinguishes left, central and right ventral cirri rather than to attempt to distinguish marginal from ventral rows simply on the basis of their position on the ventral surface. However, it is preferable to call the most posterior cirri, left and right caudal cirri, rather than left and right posterior 'marginals' as used in Hartwig and Parker (1977). The dorsal surface of Discocephalus has received less attention than that of either Euplotes (Curds, 1975) or Aspidisca (Wu & Curds, 1979) but both Dragesco (1965) and Kahl (1932) have illustrated D. ehrenbergi with six kinetics on the dorsal surface. Dorsal argyrome patterns as found in Euplotes and Aspidisca (Curds, 1975: Wu & Curds, 1979) have yet to be described. This means that the four species must currently be distinguished on the basis of their size, numbers and distribution of cirri, the presence or absence of membrane-like structures on the right of the peristome and the nature of the macronuclear apparatus. Corliss (1979) described this as a curious genus which he included only 'tentatively' in the Euplotidae and indeed, the unique body shape, the cirral arrange- ment and large number of macronuclear parts may well be considered sufficient for placing it in a separate family. Diagnosis of Discocephalus Oval marine hypotrichs with an anterior constriction of the body which forms a discoid 194 C. R. CURDS & I. C. H. WU 'head' containing the peristome and AZM on the left. Ventrally there are 4-8 frontal, 5-1 1 transverse (including satellites) and variable numbers and arrangements of ventral cirri. Posterio-dorsally there are 3-4 right caudal and 9-30 left caudal cirri. The size varies between 50-200 um long and there are numerous macronuclei. Key to the species of Discocephalus \ With 2 left ventral cirri With 7 to many left ventral cirri 2 With 5 transverse cirri but without 'pre-membranelles'. With 8-9 transverse cirri and several 'pre-membranelles' 3 Large (200 urn), row of many (about 40) left ventral cirri Small (50 urn), row of few (7-8) left ventral cirri . 2 3 D. rotatorius D. ehrenbergi D. grandis D. minimus Species descriptions Discocephalus rotatorius Ehrenberg, 1828 in Hemprich and Ehrenberg Polycoccon octangulus Sauerbrey, 1928 DESCRIPTION (Fig. 1). Medium sized (70-100 um long) marine species whose elongate, oval body is typically discocephalic. There is a well developed AZM bordering the left of the peristome area. The 7-8 frontal cirri are restricted to the anterior 'head' region. The ventral cirri are in two groups: there are 2-4 on the right body edge and 2 on the left immediately behind the peristome. There are 5 prominent transverse cirri. The caudal cirri are also in two groups and arise dorso-laterally: on the right are 3-4 large prominent caudals and on the left 20yu m Fig. 1 Discocephalus rotatorius: (a, b) after Sauerbrey, 1928 (called Polycoccon octangulus); (c) unpublished figure after Faure-Fremiet (in Dragesco, 1960). REVIEW OF EUPLOTIDAE 195 is a row of many (12-20) smaller caudal cirri. The macronucleus is divided into many randomly distributed spherical parts. NOTES. The description is based on that of Sauerbrey (1928) and on the illustration given in Dragesco (1960) but attributed to unpublished diagrams of Faure-Fremiet. Discocephalus grandis Dragesco, 1954 DESCRIPTION (Fig. 2). Large (200 um long) marine species with an uncharacteristically large number (120-150) of ventral cirri arranged in three longitudinal rows: one lies on the left body edge and two on the right. There are 4 frontal cirri which are all located along the right margin of the discoid 'head'. Immediately above the first of the long transverse cirri, on the left, are two small 'satellite' transversal cirri. There are two small right caudal and about 13 left caudal cirri. The macronucleus is divided into many (10-20) spherical parts each being 3-6 um in diameter. NOTE. This description is based on those of Dragesco (1954, 1960) who noted that the species is very similar to Holosticha discocephalus Kahl. Discocephalus ehrenbergi Dragesco, 1960 Discocephalus rotatorius Kahl, 1932 misidentification Fig. 2 Discocep ''alus grandis, after Dragesco, 1 960. 196 C. R. CURDS & I. C. H. WU DESCRIPTION (Fig. 3). This is a medium sized (90-120 um long) marine species. The presence of 7-9 transverse cirri (with 1 or 2 'satellites', Fig. 3f-h) and 5-7 'pre-membranelles' on the right of the peristome serve to distinguish it from the type species D. rotatorius Ehrenberg. The AZM consists of 18-22 membranelles arranged along the left of the peristome and there is an undulating membrane on the right. The 4-8 frontal cirri are of variable size and there are 2 left ventral, 2 mid-ventral and 4 right ventral cirri. The caudal cirri are in two groups: 3-4 right caudal and 14-20 caudal cirri on the left. There are 6 dorsal kineties with only the third from the right extending into the 'head' region (Dragesco, 1965). There is a large 30K Fig. 3 Discocephalus ehrenbergi: (a, b) ventral and dorsal surfaces, after Dragesco, 1965; (c, d) ventral and, dorsal surfaces, after Kahl, 1932 (called D. rotatorius); (e, 0 ventral surface and variations in transverse cirral arrangement, after Dragesco, 1960. REVIEW OF EUPLOTIDAE 197 number of spherical parts to the macronuclear apparatus which are scattered throughout the body but apparently not in the 'head' region. NOTES. This species was first described by Kahl (1932) as D. rotatorius Ehrenberg but was renamed and redescribed by Dragesco (1960, 1965). Later Dragesco (1968) expressed doubts about his conclusions and suggested that the species described as D. ehrenbergi in 1960 (Fig. 3e-h) might be a different species from that described in 1965 (Fig. 3a-b), although there was insufficient information to be certain. The description above is based on that of Dragesco (1965) but variations noted in other descriptions are included. Discocephalus minimus Dragesco, 1968 DESCRIPTION. Discocephalus minimus (Fig. 4) is characterised by its small size (50-60 urn long) and possession of left ventral cirri. The species has 7 frontal, 4-6 right ventral, 2 mid- ventral and 7 left ventral cirri. There are 4 right caudal and 9-10 left caudal cirri. The macronucleus is divided into relatively few (3-1 5) spherical parts. lOyu m Fig. 4 Discocephalus minimus, after Dragesco, 1 968. NOTES. The single description of this species is based on the observation of 5 individuals (Dragesco, 1968) and there are no data on the dorsal aspect of this organism. Genus DIOPHRYS Dujardin, 1841 Introduction It was Dujardin (1841) who first briefly described an organism called Diophrys marina and defined the genus Diophrys as having a discoid shape with groups of long 'cilia' at the two extremities of the body which was without a mouth. Later Stein (18590) stated that both D. marina and the earlier Stylonychia appendiculata Ehrenberg, 1838 were synonyms of 198 C. R. CURDS & I. C. H. WU Styloplotes appendiculatus Stein, 1859 (see Stein 1859a) which he characterised by the presence of three large right caudal cirri. Biitschli (1889) recognised Diophrys as a distinct genus and his list of synonyms included certain species of the genera, Stylonychia Ehrenberg, Ploesconia Dujardin, Euplotes Claparede & Lachmann, Schizopus Claparede & Lachmann, Styloplotes Stein, Styloplotes Quennestedt, Styloplotes Fresenius, Styloplotes Rees, Styloplotes Fabre-Domergue, and Styloplotes Andrusova. Although Biitschli (1889) stated that there were two species in the genus, he only illustrated Diophrys (Styloplotes) grandis Rees, 1 88 1 and failed to mention D. appendiculata. Over the next few years the combination D. appendiculata was used occasionally, for example, by Wallengren (1901) and by Calkins (1902) who established the combination Diophrys (Styloplotes) appendiculatus Stein. However, it was Kahl (1932) who first traced the taxonomic history of the species correctly. Borror (1972) recently listed eleven species of the genus with their synonyms and he designated Diophrys scutum (Dujardin, 1841) Kahl, 1932 the type species and listed D. marina as a synonym of D. appendiculata (Ehrenberg) Kahl. In view of the evidence given above, the present authors are of the opinion that Diophrys (Stylonychia) appendiculata (Ehrenberg, 1838) Kahl, 1932 is the correct name and authority for the type species of the genus Diophrys. Kahl (1932) defined the genus Diophrys as those members of the family Euplotidae with conspicuous sturdy transverse cirri and a single group of three large caudal cirri. In addition to D. appendiculata, Kahl (1932) described, and gave keys, to three other species, Diophrys (Ploesconia) scutum (Dujardin, 1841) Kahl, 1932; Diophrys hystrix Buddenbrock 1920 and Diophrys irmgard Mansfeld, 1923. Of the eleven species listed by Borror (1972) the present authors accept ten nominal species. D. tetramacronucleata Kattar, 1970 and D. multinucleata Hartwig, 1973 are two later additions to the genus, characterised by their possession of four and over twenty macron uclei respectively. The authors accept the latter as a distinct species but suspect that the former is a synonym of D. appendiculata. Two of the species, D. appendiculata and D. scutum, have been described by many authors over the past century but most of the other species are relatively recent additions. In most cases there are rather few data on the extent of intraspecific variation that might be found in potentially useful diagnostic structures. Even so, it was thought worthwhile to present a summary of the data that are available and to discuss the possible diagnostic importance of the various morphological features. (a) Shape. The typical body shape of Diophrys is an ovoid in which there is often a posterior right lateral indentation where the right caudal cirri are located. The anterior of D. hystrix is particularly truncate and the body of D. kahli is elongate. The dorsal surface of Diophrys is generally smooth, but in D. irmgard it is described with a 'trapeziform elevation' (Mansfeld, 1923). These variations are apparently distinctive although the keys here do not rely upon them for identification of these species. (b) Size. Most Diophrys species are between 50 and 120 um long. D. scutum at 1 50-200 (j.m long is the largest and D. hystrix at 30-40 um long is the smallest. Size variation within species appears to be small (Hartwig, 1973) so the size differences between D. hystrix, D. scutum and D. appendiculata (50-100 um long) are likely to be of diagnostic value. (c) Adoral zone of membranelles (AZM). Diophrys has a wide peristome which extends a third to two-thirds down the body length. On the right of the peristome there is a large, wide undulating membrane. On the left, there is a well-developed AZM which continues anteriorly over onto the dorsal surface: in some species it can return to the ventral surface down the right side of the body. Borror (1965a) stated that statistical analysis showed that the length of the right portion of the AZM in D. scutum was significantly longer from that of D. peloetes. He noted that this 'terminal portion' of the AZM in D. scutum was 0-4 the body length but only 0-3 the body length in D, peloetes. The present authors would not recommend species recognition on such a small difference as this without resort to statistical morphometric analysis but it is a useful feature for distinguishing between certain species. REVIEW OF EUPLOTIDAE 199 For example, in D. appendiculata the AZM hardly extends onto the right of the body while in D. scutum it extends almost to the central region. Rees (1883) and Kahl (1932) also consider this right extension of the AZM to be an important diagnostic feature by which they identified Styloplotes quennerstedti and D. scutum respectively. (d) Cirri. The type species, D. appendiculata, has 7-8 fronto ventral, 5 transverse, 1-3 left marginal and 3 right caudal cirri. The frontoventral cirri are arranged in two distinct groups, with 5 in the anterior right frontal group and 2-3 in the ventral group, often much smaller than the frontal cirri, lying in close proximity to the first transverse cirrus on the right. This distribution pattern is seen in all species but D. hystrix, D. irmgard and D. kahli have 9-10 frontoventrals in groups of 7 frontals and 2-3 ventrals which the authors consider to be of diagnostic importance. Some authors are in agreement with this others are not. For example, Agamaliev (1967) established a new species D. scutoides which differs from D. scutum only in having five instead of seven frontoventral cirri. However, Borror (1963) identified an organism as D. irmgard even though it possessed only five frontoventrals rather than the nine in Mansfeld's (1923) original description. Borror (1963) neither established the organism as a new species nor did he suggest the cirral difference to be due to intraspecific variation. The morphogenesis of cirri in D. appendiculata was described by Wallengren (1901). The frontoventral-transverse cirri arise from six streaks of kinetosomes as in Euplotes, with the I/I , 11/2, II/3, HI/2 and IV/2 cirri forming the frontals: V/2 and VI/2 the ventrals and II-VI/1 the transversals (Fig. 5). The transverse cirri of Diophrys are noticeably larger than those of Euplotes. There are almost invariably five transverse cirri but there are only four in D. irmgard and D. multinucleata. The presence of large, sickle-shaped, dorso-laterally attached right caudal cirri is a characteristic feature of the genus Diophrys. During morphogenesis, these cirri arise from basal bodies at the posterior ends of the ciliary rows on the right of the dorsal surface (Borror, 1972). Most of the species described have three of these cirri but D. quadricaudatus Agamaliev, 1967 has four and D. kahli Dragesco, 1963 has only one. Intraspecific variation in the number of these cirri has not yet been reported and so it is thought that this might be a useful diagnostic character. In most species, the left marginal cirri are located just posterior Fig. 5 Arrangement and numbering of cirral streaks in Diophrys appendiculata, after Wallengren, 1901. 200 C. R. CURDS & I.C. H. WU to the peristome, but in D. irmgard, D. kahli and D. multimicronucleata, they are in the 'caudal position' as are those in Euplotes and Uronychia. Hartwig (1974) believed that the positioning of these cirri in these three species was sufficient to constitute a separate genus. While the present authors agree that the caudal positioning of the left marginal cirri appears to be a significant character apparently associated with the presence of only four transverse cirri, they hesitate to erect a new genus on this alone. Mansfeld (1923) and Kahl (1932) distinguished D. irmgard from other species, not by the position of the left marginal cirri but by their number. Although most species have two left marginal cirri and D. irmgard has three, variation between 1-3 has been observed in D. appendiculata. (e) Nuclear features. The most commonly found nuclear arrangement in Diophrys is two macronuclei and 2-6 micronuclei. Exceptions to this include D. quadricaudatus, D. tetramacronudeata and D. multinucleata which have three, four and over 20 macronuclei respectively, with the diagnosis of the latter two species resting heavily on this feature. The macronuclei may be rod-shaped, ovoid or moniliform. Fig. 6 Nuclear arrangement in Diophrys: (a) Diophrys magnus, after Raikov & Kovaleva, 1968; (b-d) Diophrys scutoides, after Agamaliev, 1967; (c) Diophrys quadricaudatus, after Agamaliev, 1967; (e, 0 Diophrys hystrix, after Buddenbrock, 1920. Raikov and Kovaleva (1968) separated D. magnus from D. scutum principally on the basis of its macronuclei being moniliform, however they are similar to those of D. scutum and other species which are often shown to be slightly nodular (Fig. 6a-c). Here D. magnus and D. scutum are therefore regarded to be synonymous. Summers (1935) described the reorganisation and division of the macronuclei of D. scutum, misidentified as D. appendiculata. He noted (Fig. 7) that in the normal resting stage, the species possesses two macronuclei without a visible strand between them and a variable number of micronuclei. He observed that fragmentation of the reorganised parts of the macronuclei was not uncommon but 'fragments of the macronuclei have never been found free in the cytoplasm after the several parts fuse to form the rod-like mass'. One cannot be certain if the tripartite macronuclear structure of D. quadricaudatus (Fig. 6d) is the result of fragmentation or if it is the true resting stage, but it is likely that the sausage-shaped nucleus which Buddenbrock (1920) described in certain specimens of D. hystrix to be a divisional stage in the normally ovoid macronuclei (Fig. 6e). REVIEW OF EUPLOTIDAE 201 d Fig. 7 Division of the macronucleus of Diophrys scutum, after Summers, 1935 (called D. appendiculatd): (a) nucleus at rest; (b) first appearance of a reorganisation band at the outer pole of the posterior macronucleus; (c) reorganisation bands about to disappear at inner poles of the macronuclei; (d) fusion of the macronuclei; (e) after fusion; (0 macronucleus beginning to divide; (g) macronuclei completely divided just before daughter cells separate. Kisselbach (1936) also illustrated various stages in the nuclear development of D. appendiculata (Fig. 8a-e) one of which shows a quadripartite stage similar to that illustrated by Kattar (1970) in D. tetramacronucleata (Fig. 8f, g). In view of this D. tetramacronucleata should be strongly suspected as being a synonym of the type species. However, since one illustration by Kattar (1970) and another by Hartwig (1974) show the four ovoid macronuclei to be completely distinct (Fig. 8g) the species has been provisionally included here awaiting further data. As mentioned above, there are commonly 2-6 micronuclei in Diophrys. Borror (19650) accorded little significance to this feature and referred to Ito (1963) who stated that macronuclei may vary considerably in number within a species. (/) Dorsal silver-line system. Borror (19650) pointed out that few workers had mentioned the dorsal ciliature in Diophrys species descriptions and observed that Kahl (1932) was the first to note the presence of five rows of short cilia in D. scutum. Using the Chatton-Lwoff(1930) technique, Borror (19650) was able to show that '. . . the kinetosomes in the dorsal rows of Diophrys behave during cell division in a manner similar to the behavior of the dorsal kinetosomes in Euplotes, hence the proter and opisthe usually have the same number of rows. Within a population, with practically no exceptions, all members of the genus present have the same number of rows of cilia dorsally, and this is apparently not related with body size.' 202 C. R. CURDS & I.C. H. WU Several authors have used the number of dorsal kinetics as a diagnostic character (Borror, 19650, b: Agamaliev, 1967: Raikov & Kovaleva, 1968). However, the dorsal silver-line systems of other species including D. hystrix, D. irmgard, D. kahli, D. tetramacronudeata and D. multinucleata still remain to be described. For this reason the key here only distinguishes between D. oligothrix and D. peloetes on this character. All dorsal argyromes that have been described so far consist of a meshwork pattern and are therefore of little value for specific identification. Fig. 8 20yur Nuclear arrangement in Diophrys: (a-e) Diophrys appendiculata, after Kisselbach, 1936; (f, g) Diophrys tetramacronudeata, after Kattar, 1970. Diagnosis of Diophrys Marine hypotrichs 30-200 um in length. Ovoid body usually with prominent right posterio-lateral concavity from which arise three large sickle-shaped right caudal cirri. There are 5-10 fronto ventral, 4-6 transverse and usually 2-3 left marginal cirri. There are often two elongate, sometimes nodular, macronuclei but in some species there may be four or over twenty macronuclei. There is a variable number of micronuclei. The dorsal silver-line system consists of 4-8 dorsolateral kinetics and a mesh-like argyrome. Key to the species of Diophrys 1 With 5 frontoventral cirri With more than 5 frontoventral cirri 2 With 7-8 frontoventral cirri With 9- 10 frontoventral cirri 3 With 4 right caudal cirri With 3 right caudal cirri 4 With 1-3 left marginal cirri Without left marginal cirri 5 With 2 macronuclei With 4 or more macronuclei 6 With 5-6 dorsolateral kinetics With less than 5 or greater than 6 dorsolateral kinetics . 7 AZM extends almost to centre of right border, 1 50-200 um long. AZM hardly extends at all down right border, 50- 1 00 um long . 8 With 4 dorsolateral kinetics With 8 dorsolateral kinetics I), scutoides . . 2 . . 3 . . 10 D. quadricirratus . . 4 . . 5 D. salina . . 6 9 1 D. scutum D. appendiculata D. oligothrix D. peloetes REVIEW OF EUPLOTIDAE 203 9 With 4 macronuclei D. tetramacronucleata With 20 or more macronuclei D. multinucleata 10 With 2 left marginal cirri posterior to the peristome, 30-40 urn long .... D. hystrix Left marginal cirri in the 'caudal' position, 80-100 um long. ....... 11 1 1 With 1 right caudal and 2 left marginal/caudal cirri D. kahli With 3 right caudal and 3 left marginal/caudal cirri D. irmgard Species descriptions Diophrys appendiculata (Ehrenberg, 1838)Kahl, 1932 Stylonychia appendiculata Ehrenberg, 1838 Diophrys marina Dujardin, 1 84 1 Schizopus norwegicus Claparede & Lachmann, 1858 Styloplotes appendiculatus Stein, 1 859 Styloplotes fresenii Rees, 1883 Styloplotes appendiculatus var. pontica Andrusova, 1 886 Planiplotes wagneri Andrusova, 1 886 Diophrys appendiculatus (Stein, 18 59) Calkins, 1902 DESCRIPTION (Figs 9, 10). This, the type species of the genus, is 50-100 (im long. The body shape is typically ovoid with the characteristic lateral concavity at the posterior where the three sickle-shaped right caudal cirri arise. There are 7-8 frontoventral cirri - 5 anterior and 2-3 close to the transversals, 5 transverse and 1-3 left marginal cirri. The AZM extends down half to two-thirds of the length of the body on the left but hardly at all on the right. The two macronuclei are usually elongate to ovoid and may be smooth or nodular. There are 2-4 micronuclei and 5-6 dorsolateral kinetics each carrying 6-10 cilia. NOTES. Some of the nomenclatural history of this species has already been outlined in the introduction to the genus. Kahl (1932) transferred Stylonychia appendiculata Ehrenberg, 1838 to the genus Diophrys and redescribed the species. However, he made no reference to the fact that Stein (1859#) had already erroneously redefined the species as Styloplotes appendiculatus which combination was subsequently used by many workers (Fresenius, 1865: Quennerstedt, 1867: Kent, 1881: Rees, 1883: Fabre-Domergue, 1885). Stein (18590) suggested that Ehrenberg (1838) had overlooked the frontoventral cirri and suggested that Schizopus norwegicus Claparede & Lachmann, 1858 was probably a synonym, even though Claparede & Lachmann (1858) had distinguished their species from Stylonychia appendiculata Ehrenberg by the absence of marginal cirri. It seems likely that the two left marginal cirri were mistaken identified to be satellite transverse cirri. Calkins (1902) later transferred Styloplotes appendiculatus Stein to the genus Diophrys. Rees (1883) briefly 'described a species of Styloplotes which he stated was the same as Styloplotes appendiculatus Stein as described by Fresenius (1865) which he (Rees, 1883) proceeded to call Styloplotes fresenii. Earlier Rees (1881) had described the new species Styloplotes grandis but later (Rees, 1883) concluded that it was identical to Styloplotes norwegicus Quennerstedt, 1867 which he then erroneously called Styloplotes quennerstedti. In the present authors, opinion, Quennerstedt (1867) was mistaken in making Styloplotes norwegicus Quennerstedt a synonym of Schizopus norwegicus Claparede & Lachmann. It is here considered that the former species is a synonym of D. scutum because of the extent to which the AZM is developed on the right side of the body. Rees (1883) also used this character to distinguish Styloplotes quennerstedti, a synonym of D. scutum, from Styloplotes fresnii, a synonym of D. appendiculata. Diophrys scutum (Dujardin, 1841) Kahl, 1932 Ploesconia scutum Dujardin, 1841 (in part) 204 C. R. CURDS & I.C. H. WU 15;urn * •* » " «-J--1.9 jfa. - * •:- •: fto i> *-% • feiS-VS*!' ><V^ V^-^'V-1 • ^•-ni^.s Fig. 9 Diophrys appendiculata: (a) after Ehrenberg, 1838 (called Stylonychia appendiculatd); (b, c) after Claparede & Lachmann, 1 858 (called Schizopus norwegicus); (d, e) after Stein, 1 859a (called Styloplotes appendiculatus); (0 after Fresenius, 1865 (called Styloplotes appendiculatus); (g) after Calkins, 1902 (called D. appendiculatm; (h) after Kahl, 1932; (i,j) after Pierantoni, 1909; (k) after Andrusova, 1886 (called Styloplotes appendiculatm var. pontica; (1) after Andrusova, 1886 (called Planiplotes wagneri). 205 Fig. 10 Diophrys appendiculata, after Borror, 1963: (a) ventral surface; (b) dorsal surface; (c) nuclei. 20 um 20 urn Fig. 11 Diophrys scutum: (a) after Dujardin, 1841 (called Ploesconia scutum); (b) after Butschli, 1 889 (called Diophrys grandis); (c) after Dragesco, 1963; (d-f) ventral surface, dorsal surface, and nuclei, after Borror. 1965a. 206 C. R. CURDS & I. C. H. WU Styloplotes norwegicus Quennerstedt, 1 867 Styloplotes grand is Rees, 1881 Styloplotes quennerstedti Rees, 1 883 Diophrys grandis Butschli, 1889 Diophrys magnus Raikov & Kovaleva, 1968 Diophrys kasymovi Agamaliev, 1 97 1 DESCRIPTION (Figs 11, 12). This is the largest species (150-200 urn long) of the genus so far described. It may be distinguished from the type species, D. appendiculata, by its size and by the AZM which extends to the central body region on the right side. The body shape is ovoid with an indentation in the posterior right. The dorsal surface is smooth and arched. There are 3 large sickle-shaped right caudal cirri, 7-8 fronto ventral, 5 transverse and 2 left marginal cirri. The two elongate macronuclei may be curved, nodular or moniliform and are accompanied by up to six micronuclei. The dorsal silver-line system consists of 5-6 dorsolateral kinetics interspersed with mesh-like argyromes. f Fig. 12. Diophrys scutum: (a, b) ventral and dorsal surfaces with section showing argyromes, after Agamaliev, 1968; (c) after Raikov & Kovaleva, 1968 (called D. magnus); (d, 0 ventral argyrome, nuclei and dorsal argyrome after Agamaliev, 1 97 1 (called D. kasymovi). REVIEW OF EUPLOTIDAE 207 NOTES. Claparede & Lachmann (1858) and Stein (\S59a) believed that the three illustrations of Ploesconia scutum by Dujardin (1841) were of two different species. Claparede & Lachmann (1858) thought that one represented a Euplotes species whereas Stein (1859a) considered it to be Styloplotes appendiculatus Stein. The present authors doubt both of these opinions but agree with Kahl (1932) who identified the species as Diophrys scutum and considered the AZM originating in the middle of the right border to be an important diagnostic feature. It is mainly by this character that D. scutum can be distinguished from D. appendiculata. Raikov and Kovaleva (1968) distinguished D. magnus from D. scutum by the difference in the shapes of their macronuclei which is not a significant feature. The recent addition D. kasymovi Agamaliev, 1971 has been included here in spite of it being rather small for this species. Fig. 13 Diophrys hystrix, after Buddenbrock, 1 920: (a) ventral surface; (b, c) nuclear features. Diophrys hystrix Buddenbrock, 1920 DESCRIPTION (Fig. 1 3). Diophrys hystrix is a small (30^0 urn long) species. The body outline is generally oval but it is truncated anteriorly and there is the usual concavity on the posterior right accommodating three large sickle-shaped right caudal cirri. The dorsal surface is strongly arched. The ten frontoventral cirri are arranged in two distinct groups with 7 'frontals' at the anterior on the right of the peristome and 3 'ventrals' near the transverse cirri. One of the 'ventrals' is adjacent and similar in size to the transversals, but it points in the opposite direction and is used in the creeping movements of the animal. There are 4 long transverse cirri and 2 small left marginal cirri located just behind the peristome. There are two ovoid macronuclei. NOTES. Kahl (1932) gave an almost identical description and illustration of this species as in Buddenbrock's (1920) original. Kattar (1970) identified a small (35-40 urn) species with two ovoid macronuclei as D. hystrix but this is a dubious identification since the author gave an inadequate description and the illustration was of a different shape and cirral number to that of Buddenbrock (1920). Diophrys irmgard Mansfeld, 1 923 DESCRIPTION (Fig. 14). This is a medium sized (75-135 urn long) marine species. The body shape is characteristic, being broadly oval in outline but tending to be rectangular. The wide peristome is approximately half the body length and there is a prominent undulating 208 C. R. CURDS & I. C. H. WU m Fig. 14 Diophrys irmgard: (a, b) after Mansfeld, 1923; (c, d) after Kahl, 1932; (e) after Dragesco, 1 963 ;(f) after Borror, 1963. membrane on the right. The AZM bordering its left edge curves around the anterior end but only just extends to the right side of the body. There are 3 right caudal, 9 frontoventral, 4-5 transverse and 3 left marginal cirri. The two ovoid macronuclei are 8 urn in diameter and each is associated with a micronucleus. NOTES. This species may be distinguished from the type species, D. appendiculata, by the presence of 9 instead of 7 frontoventral cirri and because the left marginal cirri are in the 'caudal' position. The shape of its body is consistently observed to be widely oval, rectangular and lacks the posterior lateral concavity on the right which is usually charac- REVIEW OF EUPLOTIDAE 209 teristic of the genus. Additionally, the right caudal cirri are attached dorsally like those of Uronychia. Horror (1963) described an organism which he called D. irmgard but as it had only 5 frontoventral cirri perhaps future studies will show this to be a separate species. Diophrys salina Ruinen, 1938 DESCRIPTION (Fig. 1 5). This is a small (3CMO um long) species. The outline shape of the body is characteristically oval without any obvious lateral concavities but there is a posterior indentation where the 3 large caudal cirri arise. The dorsal surface is strongly convex, but the ventral surface is flattened. The peristome region extends to the centre of the body, with an AZM on the left and a well developed undulating membrane on the right. The frontoventral cirri are arranged in two groups with 4 right anterior 'frontals' and 4 'ventrals' situated immediately behind, and to the right of, the peristome. There are no left marginal cirri. Five transverse cirri lie between the caudal and 'ventral' cirri. The original description did not include any details concerning the nuclear apparatus. Feeds on diatoms, algae and bacteria. Fig. 15 Diophrys salina: (a, b) ventral surface and lateral view, after Ruinen, 1 938. Diophrys kahli Dragesco, 1 963 DESCRIPTION (Fig. 16). This species is about 80 um long, the body is elongate with a short posterior narrowed tail region. The peristome is small, bordered on the right by a well developed undulating membrane and on the left by a small AZM. The frontoventral cirri consist of a group of 7 long 'frontals' and 2 small 'ventrals'. The 5 transverse cirri are long, the 2 left marginal cirri are in the 'caudal' position and there is only one right caudal cirrus. The two oval macronuclei are connected by a nuclear membrane and there are 4-6 micronuclei. A few cilia have been observed along the left border of the animal. NOTES. Dragesco (1963) identified an organism that he considered to be identical to one incompletely studied by Kahl (1932) which he called D. kahli. Untypically, the body of this species is rather elongate and its left marginal cirri emerge caudally instead of immediately posterior to the peristome. Hartwig (1974) grouped this species with D. irmgard and D. 210 C. R. CURDS & I.C. H. WU Fig. 16 Diophrys kahli: (a, b) ventral surface and dorsal plaques, after Dragesco, 1963; (c) dorsal surface, after Kahl, 1932 (called an 'incompletely studied Diophrys species'). multinucleata because of this latter feature. In contrast to other species in the genus, D. kahli has only one right caudal cirrus, its peristome is rather small and the AZM is under- developed. Dragesco (1963) described the presence of small oval plaques on the dorsal surface (Fig. 14b) which he suspected to be 'protrichocysts'. Diophrys oligothrix Borror, 1 965 DESCRIPTION (Fig. 17). Diophrys oligothrix is a medium sized (79-106 urn long), ovoid species. The concavity at the posterior right edge, so typical of the genus, is here incon- spicuous and the dorsal surface smooth. The AZM bordering the left edge of the large peristome continues dorsally along the anterior region to the right side of the body. The ciliature and nuclear features are also typical of the genus, there are 7 fronto ventral, 5 transverse, 2 left marginal and 3 right caudal cirri. The two irregular, elongate macronuclei are usually accompanied by four micronuclei. The silver-line system consists of 3 dorsal kinetics, one lateral kinety on the right and a fine mesh-like argyrome. The dorsal kineties bear, from left to right, 13-20, 16-24, 12-18 cilia and the ventral kinety 9-13 cilia. NOTE. This species is distinguished from D. scutum on the basis of its different number of kineties. Diophrys peloetes Borror, 1965 DESCRIPTION (Fig. 18). D. peloetes is a medium sized (95-135 urn long) species typical of the genus. It has a wide peristome which is about two-thirds of the body length, bordered by a well developed AZM on the left and an undulating membrane on the right. The AZM travels along the anterior dorsal edge onto the right side of the body where it extends about 3/10 of the body length. There are 3 prominent right caudal cirri, 5 long transverse, 7 frontoventral and 2 left marginal cirri. The two macronuclei are elongate. There are 8 dorsolateral REVIEW OF EUPLOTIDAE 211 Fig. 17 Diophrys oligothrix, after Borror, 19656: (a) ventral surface; (b) dorsal surface; (c) frontal section showing nuclei. kinetics, each bearing 6-17 cilia. The number of kinetics distinguishes this species from D. scutum which has only five. NOTES. Borror (1965a) established D. peloetes after a morphometric comparison with D. scutum. He stated that the new species was 'extremely similar to D. scutum except for having eight dorsal rows of cilia instead of five, having fewer cilia per row, and having a significantly shorter AZM'. He also pointed out that he had identified it incorrectly as D. scutum in an earlier study (Borror, 1963). Diophrys quadricaudatus Agamaliev, 1967 DESCRIPTION (Fig. 19). This is a medium sized (100-1 10 urn long) species, characterised by the presence of 4 right caudal cirri arising from a particularly prominent concavity on the posterior right of an otherwise oval body. The wide peristome is about 48 um long and on its right there is a conspicuous undulating membrane. The AZM is composed of 50-60 membranelles which extend forward over to the right side of the body. There are 7 fron to ventral, 5 transverse, and 3 left marginal cirri. The dorsal silver-line system consists of 5 or 6 dorsolateral kinetics and a finely-meshed dorsal argyrome. There are two anterior and one posterior macronuclei. 212 C. R. CURDS & I. C. H. WU Fig. 18 Diophrys peloetes: (a, b) ventral and dorsal surfaces, after Borror, 1963 (called D. scutum); (c-e) ventral and dorsal silver-line systems, and nuclei, after Borror, 1965a. NOTES. Agamaliev (1967) considered the presence of four right caudal cirri and three macronuclei to be the diagnostic features of this species. The uneven number of macron uclei is rather strange and could perhaps represent an interdivisional state. Diophrys scutoides Agamaliev, 1967 DESCRIPTION (Fig. 20). D. scutoides is 1 10-120 urn long. The body is oval with a prominent concavity on the posterior right edge. The AZM of 75-80 membranelles borders the left edge of a wide peristome and continues along the anterior edge to extend a third of the body length REVIEW OF EUPLOTIDAE 213 20yum Fig. 19 Diophrys quadricaudatus, after Agamaliev, 1967: (a) ventral surface of living cell (b-d) stained ventral surface, dorsal surface and nuclei. down the right side. There are 3 right caudal, 5 transverse and 2 left marginal cirri but only 5 frontoventral cirri. The two elongate macronuclei are nodular and are accompanied by three micronuclei. The silver-line system consists of 5 dorsolateral kinetics with mesh-like dorsal and ventral argyromes. 214 C. R. CURDS & I. C. H. WU Fig. 20 Diophrys scutoides, after Agamaliev, 1967: (a) ventral surface; (b) dorsal surface; (c, d) ventral and dorsal argyromes. NOTES. Agamaliev (1967) described this species from the Caspian Sea. Apart from being slightly smaller in size, it differs from D. scutum in having five instead of seven frontoventral cirri. Diophrys tetramacronucleata Kattar, 1970 DESCRIPTION (Fig. 21). This is a small (55-65 urn long) species. The body is oval except for the concavity at the posterior right edge. The AZM consists of about 36 membranelles which extend about halfway down the body on the left but hardly at all on the right. There are 7 frontoventral, 5 transverse, 2 left marginal and 3 right caudal cirri. There are 5 dorsolateral kinetics and 4 ovoid macronuclei. NOTES. The original description of this species was brief and only the presence of four macronuclei distinguished it from the type species. Although it is suspected that Kattar (1970) described an interdivisional specimen, it is provisionally included here as a nominal species. Kattar (1970) stated that protargol impregnation showed the presence of three median and two dorsolateral kinetics he provided no diagram of these structures. The REVIEW OF EUPLOTIDAE 215 Fig. 21 Diophrys tetramacronucleata, after Kattar, 1 970: (a) ventral surface; (b) nuclei. redescription and photographs of this species by Hartwig (1974) are also incomplete although the presence of four macronuclei was clearly demonstrated. Diophrys multinucleata Hartwig, 1973 DESCRIPTION (Fig. 22). D. multinucleata is a medium sized (76-11 Sum long) highly thigmotactic species. The body is oval to rectangular in outline with the dorsal surface being arched and the ventral surface flattened. There is a small but distinct projection on the anterior right corner of the body. The peristome is about two-thirds of the body length. The AZM consists of about 30 membranelles lying along the left of the peristome and a few larger membranelles along the anterior edge of the body. The frontoventral cirri are arranged in two distinct groups: the 5-6 large 'frontals' are in the anterior and the two very small 'ventrals' lie close to the transverse cirri. There are 4 long transverse, 3 right caudal and 3 left marginal/caudal cirri. There are at least 20 macronuclei present. NOTES. This species is characterised by the presence of over twenty macronuclei which is unique in the genus, otherwise it is similar to D. irmgard in cirral arrangement, particularly in the caudal positioning of the left marginal cirri which Hartwig (1973, 1974) considered to be a feature of diagnostic importance. Genus URONYCHIA Stein, 1859 Introduction Stein (1859#, 18596) established and described the genus Uronychia and transferred Trichoda transfuga Muller, 1786 to the genus as the type species. Between 1901 and 1928, five new species were described and Kahl (1932) included a key to them in his classical compendium. Since then only one addition, Uronychia bivalvorum Fenchel, 1965, has been 216 C. R. CURDS & I.C. H. WU Fig. 22 Diophrys multinucleata, after Hartwig, 1973: (a) dorsal surface; (b) ventral surface showing nuclei. made which he found in the mantle cavity of certain lamellibranch molluscs. Uronychia is characterised by its enormous peristome region occupying half of the ventral surface with conspicuous peristomial membranes, the three posterior groups of large cirri, the apparent absence of frontoventral cirri and by its rapid backward motion (Bullington, 1940). How- ever, there are few features which clearly distinguish the described species from one another. Many of the features used in the past are variable so that here only four nominal species are recognised. (a) Shape. The typical Uronychia body is oval. Dorsal ribs, ridges or striations are often mentioned in descriptions but there are few data on the variability of these structures. Ventrally, there are two large posterior cavities which accommodate the transverse and left marginal cirri. In general, the right caudal cirri of Uronychia are attached more dorsally than those in Diophrys, so the oval body outline is without the dorsolateral concavity at the posterior right which is characteristic of the latter genus. However, Buddenbrock (1920) described U. heinrothi with an 'Ausschnitt' (notch) on the posterior right edge which can make the posterior border S-shaped. Similarly, Taylor (1928) described an 'uncinus' on U. uncinata which he stated apparently owes its origin in part to an attenuation of the remnant which holds proter to opisthe during the final stages of division. It seems likely that the 'Ausschnitt' and 'uncinus' are the same structure and as Buddenbrock (1920) noted that it was variable in extent and absent from some individuals then it cannot be used as a reliable diagnostic character. Indeed if it is formed during division then it could only be present in the proter of a dividing cell. (b) Size. The distinctive sizes of U. magna and U. setigera are here considered to be REVIEW OF EUPLOTIDAE 217 diagnostically significant. The former at 450 um long is the largest species so far described in the family Euplotidae, and the latter at 40-50 jim long is the smallest Uronychia species. The sizes of the remaining species fall within the range of 70-250 um long. The size of the type species U. transfuga has been noted to vary between 50-1 50 um long (Kahl, 1932) but Bullington (1940) separated U. heinrothi from U. transfuga by the larger size (129-264 um long) of the species he observed. However, Buddenbrock (1920) described U. heinrothi as having the range 70-250 urn in length. It is apparent that the size variation of these two species is great and their ranges overlap. Since there are no other significant distinguishing features, these two species are here regarded as being synonymous. (c) Adoral Zone of Membranelles. The ventral surface of Uronychia is dominated by an enormous peristome with conspicuous membranelles and membranes. Unlike the rest of the Euplotidae, the AZM of Uronychia consists of large membranelles along the anterior of the body and 4-5 smaller paroral membranelles at the posterior left of the peristome and there are undulating membranes along both sides of the peristome. Fenchel (1965) was of the opinion that it was the fusion of the adoral membranelles which forms the membrane along the left peristomial border. These peristomial membranes and membranelles may be observed to be closed over the peristome region or spread out and wing-like. The paroral membranes are often found in a pocket-like invagination of the peristomial wall. Buddenbrock (1920) described the presence of two large peristomial membranes in U. heinrothi but these appear to be split into five parts in one of his diagrams. Bullington (1940) observed four peristomial membranes on his specimens of U. heinrothi plus another large membrane close to the posterior right edge of the body. This marginal membrane has been described only on this occasion so it has not been used here as a diagnostic character. Although the peristomial membranes of U. heinrothi appear to be larger and more numerous than has been observed in U. transfuga, it is not considered to be a reliable character. On the other hand, Calkins (1902) described 'flagella-like' cirri in the peristome of U. setigera which have subsequently been noted by other authors (Buddenbrock, 1920; Young, 1922; Kahl, 1932; Kattar, 1970). This feature is apparently distinctive and consistent and is therefore useful in the identification of U. setigera. Fig. 23 Arrangement and numbering of cirral streaks in Uronychia transfuga, after Wallengren, 1901. 218 C. R. CURDS & I.C. H. WU (d) Cirri. One of the most distinctive generic features of Uronychia is the apparent absence of frontoventral cirri. Wallengren (1901) studied cirral morphogenesis in U. transfuga and was first to number the cirral streaks (Fig. 23). He found that there was a small residuum of cirral elements I/I, II/2 and 111/2 grouped closely together at the anterior right near the adoral membranelles which he described as membranous cirri. Young (1922) noted these in three Uronychia species and described them as cirri-like membranelles, but it was Buddenbrock (1920) who illustrated three similar small cirrus-like structures at the anterior left as well as on the right. Wallengren (1901) showed that the cirri V/2 and VI/2 which form the 'ventrals' in Euplotes and Diophrys lie among the transversals in U. transfuga and they appear like 'satellites' in this group of cirri. These cirri have not yet been observed by other authors but Buddenbrock (1920), Young (1922) and Taylor (1928) described the presence of one slender cirrus at the right of the transversals in U. setigera, U. heinrothi and U. uncinata. All species of Uronychia have 4 or 5 transverse cirri. Young (1922) considered the possession of four transversals in U. binucleata to be a specific character even though he recorded that the number of transversals in U. transfuga varied between 4 and 5. To the left of the ventral cavity from which the transversals emerge, there is another cavity which accommodates the two enormous left marginal cirri with a variable number of small cirri or cilia. The right caudal cirri emerge dorsally on the posterior right and are invariably sickle- shaped. All of the described species have three right caudals except U. magna which was shown as having two by Pierantoni (1909), although he also observed only two right caudals in U. transfuga which others have shown to possess three. Bullington (1940) discussed the attachment and movement of the right caudal cirri in Uronychia (Fig. 24). In addition to these three groups of large cirri, two small right marginal cirri have been observed in most Uronychia species. Fenchel (1965) distinguished U. bivalvorum from U. transfuga partly by the absence of these two small cirri but it should be noted that both U. transfuga and U. setigera have also been described without right marginals. Fig. 24 Arrangement of the right caudal cirri of Uronychia transfuga, after Bullington, 1940 (called U. heinrothi): (a) showing two large cirri attached in the mid-dorsal region of the posterior body end with a cirrus on the right; (b) showing two defimbriated cirri attached to either side of the mid-line and one cirrus attached in a pocket near the right edge and slightly below the other two cirri. REVIEW OF EUPLOTIDAE 219 Fig. 25 Stages in cell division of Uronychia transfuga, after Calkins, 1911: (a) resting stage; (b) condensation of the macronucleus; (c, d) later stages in division; (e) just before cell separation; (f-h) daughter cells immediately, 15 minutes and 1 hour after separation. Kahl (1932) noted the presence of a long slender right caudal cirrus in U. binucleata which he considered to be of diagnostic value, similarly Young (1922) described such a cirrus in U. setigera although no others have reported its presence. It is evident that cirral numbers and arrangements in this genus are highly variable and therefore of little diagnostic importance. (e} Nuclear features. Kahl (1932) relied heavily on the nuclear features of Uronychia in his key to the species. For example, he stated that U. transfuga had, without exception, two sausage-shaped macronuclei with a micronucleus and that U. magna and U. heinrothi had their nuclei split into many fragments. However, U. transfuga had already been seen with its macronucleus in many fragments. Calkins (1911) described the nuclear reorganisation of U. transfuga and showed that the macronucleus just after cell division was in two parts but that it was a fragmented C-shape when at the resting stage (Fig. 25). The macronucleus of U. transfuga has been described as having a fragmented C-shape, like a string of beads or partially fused, and in two parts (Fig. 26) (Buddenbrock, 1920; Bullington, 1940). Borror (1972) has also noted that the macronuclear shape and number were variable and for this reason considered U. heinrothi to be synonymous with the type species. Calkins (1902) described U. setigera with a single ovoid macronucleus but Young (1922) observed two irregular macronuclei in his specimens of the same species. Fenchel (1965) distinguished U. bivalvorum from the type species partly on the basis of its nucleus which he described as 'an irregular structure divided into two or more parts of unequal size': this would lie within the range of variability already noted above for U. transfuga. Kattar(1970) distinguished between U. transfuga and U. setigera by their possession of 9-15 and 2 nodular macronuclei respectively, although he also concluded that the six species recognised by Kahl (1932) including U. setigera could be varieties of U. transfuga. Although the number and shape of the macronuclei in Uronychia appear to be highly variable this is not the case with 220 C. R. CURDS & I. C. H. WU € ^0 Fig. 26 Nuclear variation in Uronychia transfuga, after Buddenbrock, 1920 (called V. heinrothi). the micronucleus. Most species possess a single micronucleus but U. binucleata is charac- terised by the presence of two micronuclei. Only one other species, U. magna, has been recorded with two micronuclei. (/) Dorsal silver-line system. Kattar (1970) noted the presence of four kinetics on the dorsal surface of U. transfuga and five on U. setigera, while Reiff (1968) illustrated five dorsolateral kinetics on the former species. The kinetics which have only recently been described appear to correspond in number and position with the dorsal ridges and striations that are sometimes described by earlier authors. However, far more data are required before the diagnostic importance of the silver-line systems of Uronychia can be assessed. Diagnosis of Uronychia Marine hypotrichs of variable size, mostly within the range 50-250 urn long, but up to 450 um long. Body oval and smooth in outline, dorsal surface smooth or with ridges. Peristome large with conspicuous membranes. The AZM is limited to the anterior border and the paroral region. There are 4-5 transverse and 2 left marginal cirri which emerge from prominent ventral cavities. The 3 large right caudal cirri are attached to the dorsal surface and there are sometimes 2 right marginal cirri present. The frontoventral cirri are reduced to a field of 3 near the origin of the AZM. The macronuclei are variable in number and shape and there are 1 or 2 micronuclei. Characteristically moves backwards rapidly. Key to the species of Uronychia 50-250 um long Smaller than 50 um long or larger than 250 um long With a single micronucleus With two micronuclei Peristomial cirri present Peristomial cirri absent 40-50 um long About 450 um long About 450 urn long, macronucleus moniliform and C-shaped 60-80 um long, macronucleus in 3-5 pieces .... 2 4 3 5 U. setigera U. transfuga U. setigera U. magna U. magna U. binucleata Species descriptions Uronychia transfuga (Muller, 1 786) Stein, 1 859 Trichoda transfuga Muller, 1 786 Ploesconia scutum Dujardin, 1841 (in part) Campylopus paradoxus Claparede & Lachmann, 1 858 Uronychia heinrothi Buddenbrock, 1920 Uronychia uncinata Taylor, 1928 Uronychia bivalvorum Fenchel, 1965 REVIEW OF EUPLOTIDAE 221 f -•M- P Fig. 27 Uronychia transfuga: (a, b) ventral and dorsal surfaces, after Stein, 1859a; (c, d) ventral and dorsal surfaces, afier Claparede & Lachmann, 1858 (called Campylopus paradoxus); (e) dorsal surface, after Dujardin, 1841 (called Ploesconia scutum); (f, g) ventral and dorsal surfaces showing nuclei, after Pierantoni, 1909; (h) ventral surface and nuclei, after Calkins, 1911; (i) dorsal surfaces and nuclei, after Young, 1922. 222 C. R. CURDS & I. C. H. WU b FMZ vFM rc IMC Fig. 28 Uronychia transfuga: (a-c) ventral and dorsal surfaces showing nuclei, after Kahl, 1 932 (c called U. uncinata); (d-f) ventral and dorsal surfaces and nuclei, after Fenchel, 1965 (called V. bivalvorum); (g, h) ventral surface and dorsal surfaces showing nuclei, after Reiff, 1968. REVIEW OF EUPLOTIDAE 223 Fig. 29 Uronychia transfuga: (a, b) ventral surface and nuclei, after Kattar, 1970; (c) ventral surface, after Fenchel, 1965 (called U. bivalvorum)', (d-g) ventral surface, dorsal surface showing nucleus, ventral view and lateral view of peristomial membranes, after Buddenbrock, 1920 (called U. heinrothi); (h) ventral surface, after Bullington, 1940 (called U. heinrothi); (i) dorsal surface, after Taylor, 1928 (called U. uncinata). 224 C. R. CURDS & I.C. H. WU DESCRIPTION (Figs 27, 28 & 29). This is a cosmopolitan species. The oval shaped body is variable in size (50-260 urn long), its dorsal surface is arched and may be smooth or with 3-4 ridges. At the posterior right there are the 3 characteristically sickle-shaped right caudal cirri. The large peristome and two posterior cavities occupy most of the ventral surface. Prominent adoral membranelles are situated along the anterior edge of the body and these emerge dorsally. At the posterior left of the peristome, there are 4-5 paroral membranelles lying in a pocket-like invagination. Large undulating membranes border two sides of the peristome. There are 4-5 large transverse cirri implanted in the larger posterior cavity on the right, sometimes with 1 or 2 satellite cirri. In the posterior left cavity there are 2 large marginal cirri sometimes accompanied by a few, usually 2, small cirri or cilia. The macronucleus varies from being a moniliform (5-13 segments) C-shape at resting stage, to being 2 irregular masses immediately after cell division. The silver-line system consists of 3-5 dorsolateral kinetics. It has been observed in the mantle cavities of the lamellibranch molluscs Thyasiraflexuosa and T. sarsi. 10JJ Fig. 30 Uronychia setigera: (a) after Calkins, 1902; (b-d) after Young, 1922; (e) after Kattar, 1970. REVIEW OF EUPLOTIDAE 225 NOTES. Stein (1859<2, b) established the genus Uronychia and redescribed U. (Trichoda) transfuga Muller as the type species. U. transfuga has since been identified by many workers from various localities (see Hartwig 1973, 1974). As discussed earlier U. heinrothi, U. uncinata and U. bivalvorum were established on characters that are now known to be variable and unreliable. These three species are here regarded as synonyms of the type species until more convincing data become available. Uronychia setigem Calkins, 1 902 DESCRIPTION (Fig. 30). This is the smallest (40-50 urn long) species yet described. The dorsal surface is arched and is sculptured longitudinally by 3-4 ridges. There are 2-3 flagella-like cirri in the large peristome and there are about 4 paroral membranelles. Wide undulating membranes lie on each side of the peristome. There are 3 curved right caudal cirri attached dorsally and a long thin satellite cirrus has been observed. In the two ventral cavities there are 4-5 transverse cirri and 2 large left marginal cirri. The macronucleus is usually in 2 band- like parts with a micronucleus between them but a single spherical macronucleus has also been observed in this species. There are 5 dorsolateral kinetics. NOTES. This species is characterised by the presence of flagella-like cirri extending from the posterior left margin into the peristome (Calkins, 1902). This author further distinguished it from the type species by its single ovoid macronucleus; however later authors (Young, 1922; Kattar, 1970) reported two macronuclei. Kattar (1970) impregnated the cell with protargol but failed to clearly illustrate the silver-line system. cl ..ctrr. cl SOyum Fig. 31 Uronychia magna, after Pier^.ntoni, 1 909; (a) ventral surface; (b) dorsal surface. 226 C. R. CURDS & I. C. H. WU Uronychia magna Pierantoni, 1909 DESCRIPTION (Fig. 3 1 ). This is the largest species yet recorded (450 um long). The body shape is approximately oval in outline but is ornamented at either end. The anterior dorsal edge is serrated and there are two short spines on the posterior left dorsal border. The dorsal surface is longitudinally striated. The peristome is extensive, occupying most of the ventral surface. The AZM is located anteriorly in a posterior pocket in the peristome. There are two large undulating membranes, one on each side of the peristome. There are 6 transverse, 2 left marginal and 3 right caudal cirri. The macronucleus is in many pieces forming a string of beads which follow the curve of the left side of the body so that it is C-shaped. Anteriorly there are 2 micronuclei. NOTE. This species has apparently been described on a single occasion. Uronychia binucleata Young, 1 922 DESCRIPTION (Fig. 32). Uronychia binucleata is 60-80 urn long. The dorsal surface is arched 10yum Fig. 32 Uronvchia binucleata: (a-c) ventral surface, dorsal surface and nuclear features, after Young, !922;(d)afterKahl, 1 932. REVIEW OF EUPLOTIDAE 227 and decorated with many small pits. The peristome is bordered on either side by a large undulating membrane and at the anterior left there are 3 delicate sickle-shaped membranelles. About 4 paroral membranelles lie in the 'buccal' pocket. There is a long slender cirrus accompanying the 3 curved right caudal cirri, 4 transverse, 2 left marginal and 2 right marginal cirri. The macronucleus is in 3-5 fragments and 2 micronuclei. NOTES. Young (1922) established this species which he showed to be almost identical to U. setigera in his comparative study. He distinguished his species by the absence of peristomial cirri, the presence of 4 or less transverse cirri, and the presence of a slender right caudal cirrus in addition to the two micronuclei. Although Young (1922) described a satellite cirrus in U. setigera which he considered to be significant, curiously he failed to mention it in U. binucleata even though he illustrated it. Here the presence of two micronuclei is used to characterise the species: should future studies show that the number of micronuclei to be variable, then it would become synonymous with U. transfuga. Genus CERTESIA Fabre-Domergue, 1885 Introduction Fabre-Domergue (1885) described an organism that was very similar to Euplotes except that it had a row of left marginal cirri, no caudal cirri and the macronucleus was in four parts. In his view this was sufficient to create the new genus Certesia although later both Biitschli (1 889) and Sauerbrey (1928) considered it to be a subgenus of Euplotes. Since the description of the type species, Certesia quadrinucleata Fabre-Domergue, 1885, only one other species, Certesia ovata Vacelet, 1960, has been described. Vacelet (1960) distinguished it from the type species on account of its smaller size, its more oval shape and its two curved left transverse cirri. Here, these differences are not considered to be sufficient to treat C. ovata as a separate species. Diagnosis of Certesia Oval marine hypotrichs with an anterior nose-like projection on the right anterior body edge. There is a conspicuous AZM which extends a third to halfway down the left side of the body. There are 1 1-13 frontoventral, 5 large transverse, and a variable number (6-1 1) of left marginal cirri. There are no caudal cirri. Macronucleus in several parts. Single species genus. 20/jm Fig. 33 Certesia quadrinucleata: (a) after Fabre-Domergue, 1885; (b) after Sauerbrey, 1928; (c) after Kahl, 1932;(d, e) after Vacelet, 1960 (called C. ovata). 228 C. R. CURDS & I. C. H. WU Species description Certesia quadrinucleata Fabre-Domergue, 1885 Certesia ovata Vacelet, 1 960 DESCRIPTION (Fig. 33). Certesia quadrinucleata is a medium sized (75-80 fim long), oval, rigid and colourless marine hypotrich. The dorsal surface is arched and smooth: the ventral surface flat. The right body border is convex and the left may be slightly concave. There is a distinct nose-like projection on the right of the extreme anterior body edge. The peristome is a third to a half of the body length. The AZM consists of about 5 large membranelles along the anterior border and 1 5-20 smaller ones along the left edge of the peristome. There are 1 1-13 frontoventral cirri, 5 large transverse cirri, a row of 6-1 1 left marginal cirri but no caudal cirri. Four ovoid macronuclei are located in pairs, one pair on the right anterior and one pair on the left below the AZM. Genus GASTROCIRRHUS Lepsi, 1928 Introduction Lepsi (1928) created the genus Gastrocirrhus and stated that the type species Gastrocirrhus intermedium Lepsi, 1928 possessed characters that were intermediate between the oligotrichs and the hypotrichs. The organism had ventral cirri arranged in groups like those of hypotrichs, but its large anterior funnel-shaped peristome and spiral AZM were more like those of oligotrich genera such as Stentor. Kahl (1932) thought that the organism was probably a piece of a fragmented Oxytricha, but soon after Bullington (1940) established another species Gastrocirrhus stentoreus Bullington, 1940. This has been followed by several other species descriptions. The six cirri along the right side of G. intermedius are here interpreted to be frontoventrals and the remaining ten cirri are called caudals. Bullington (1940) recorded the presence of four marginals, four ventral and two oral/anterior cirri on G. stentoreus. These are considered to be frontoventral cirri so that this species may be diagnosed by the presence of only five caudal cirri. In Gastrocirrhus adhaerens Faure-Fremiet, 1954, there are 16 cirri arranged in two rows on the right of the peristome, and 12 in a semi-circle at the posterior. Here, these are interpreted to be frontoventral and caudal cirri respectively. Gastrocirrhus trichocystus Ito, 1958 has 18 frontoventral and 13 caudal cirri arranged similarly to those in G. adhaerens but the species is characterised by the presence of zones of trichocysts (mucocysts?) on the dorsal and ventral surfaces. Faure-Fremiet (1961) created the family Gastrocirrhidae and included the single species genus Cirrhogaster Ozaki & Yagui, 1942 in the family. The type species, Cirrhogaster monilifer Ozaki & Yagui, 1942 is similar to G. adhaerens, but the former species has 10 rather than 16 frontoventral cirri. Dragesco (1965) suggested that these two species were synonymous but here, although C. monilifer is considered to be a species of Gastrocirrhus it is not considered to be a synonym of G. adhaerens. Diagnosis of Gastrocirrhus Marine hypotrichs that may be dorso vent rally flattened or cup-shaped. There is a large anterior funnel-shaped peristome which opens both anteriorly and ventrally. A well developed AZM borders the C-shaped anterior body edge and winds anti-clockwise down the left of the peristome. There are 5-18 frontoventral cirri, usually arranged in two oblique rows on the right of the peristome: 5-13 caudal cirri along the posterior pole of the body which in some species curve forwards ventrally on the left to give the appearance of transverse cirri. Macronucleus may be oval or moniliform in 11-15 pieces. REVIEW OF EUPLOTIDAE 229 Key to the species of Gastrocirrhus \ With 10 fronto ventral cirri 4 With 6, or more than 10 frontoventral cirri 2 2 With 6 frontoventral cirri G. intermedius With more than 10 frontoventral cirri 3 3 With 1 6 frontoventral cirri and 1 2 thigmotactic caudal cirri, without 'trichocyst' zones G. adhaerens With 1 8 frontoventral cirri, 1 3 caudal cirri and with dorsal and ventral zones of 'trichocysts' G. trichocystus 4 With 5 caudal cirri G. stentoreus With 12-13 caudal cirri G.monilifer 10/jm Fig. 34 Gastrocirrhus intermedius, after Lepsj, 1 928. Species descriptions Gastrocirrhus intermedius Lepsi, 1928 DESCRIPTION (Fig. 34). This species is a dorso ventral ly flattened cup-shape, approximately 70 jim long. The well developed AZM borders the anterior funnel-shaped peristome. There are 16 cirri in three distinct groups. Near the right body margin there are 6 frontoventral cirri. The caudals are situated along the posterior pole, comprised of a group of 3 sickle- shaped cirri, rather like the right caudal cirri in Diophrys, and 7 others to their left which are smaller and straighten The macron ucleus is oval. NOTES. There is only a single description of this, the type species of the genus. The observations of Lepsi (1928) appear to have been made exclusively on living specimens. The arrangement of the cirri and nuclear features do not appear to be as typical as those of the species described later. Gastrocirrhus stentoreus Bullington, 1940 DESCRIPTION (Fig. 35). Gastrocirrhus stentoreus is a medium sized (100 urn long, 70-80 um wide) perfectly cup-shaped species. The large funnel-shaped peristome has a ventral, elongate opening about two-thirds of the body length and is bordered by a prominent AZM. There are 1 1 frontoventral cirri on the right of the peristome in groups of two, four and five cirri. At the posterior right margin, there are 5 sickle-shaped caudal cirri. 230 C. R. CURDS & I. C. H. WU ^ SOiim Fig. 35 Gastrocirrhus stentoreus, after Bullington, 1 940. Fig. 36 Gastrocirrhus adhaerens: (a) ventral surface; (b) attached to substratum showing nuclei. Both after Faure-Fremiet, 1954. Gastrocirrhus adhaerens Faure-Fremiet, 1954 DESCRIPTION (Fig. 36). This is a medium sized (100 urn long), typically cup-shaped species. The peristome diameter is slightly less than the body length. The AZM, which winds around the anterior of the cell and down the left side of the peristome, consists of about 150 membranelles. The species is characterised by its 12 very long thigmotactic caudal cirri along the posterior border of the cell which can be retracted when not attached to a substratum. There are 16 frontoventral cirri arranged in two rows of 8 cirri on the right of the REVIEW OF EUPLOTIDAE 231 peristome. The moniliform macronucleus is composed of about 12 pieces: 3-5 micronuclei have been observed. Gastrocirrhus monilifer n. comb. Cirrhogaster monilifer Ozaki & Yagui, 1942 DESCRIPTION (Fig. 37). Gastrocirrhus monilifer is 95-105 urn long, 75-90 urn wide and cup- shaped. The ventral opening into the large funnel-shaped peristome is about a half the body length. The 10 frontoventral cirri, arranged in two rows, are restricted to the small area on the right of the peristome. There are 12 long caudal cirri. The moniliform macronucleus consists of 1 1-1 5 pieces and there are 8 micronuclei scattered along its length. NOTES. Dragesco (1965) suggested that this species should be a synonym of G. adhaerens. Here it is considered to be a separate species until further information concerning the variability in numbers of frontoventral cirri become available. Fig. 37 Gastrocirrhus monilifer, after Ozaki & Yagui, 1 942 (called Cirrhogaster monilifer). Gastrocirrhus trichcystus Ito, 1958 DESCRIPTION (Fig. 38). Gastrocirrhus trichocystus is 90-103 um