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. "^ n ^ "> *^ ^ ' .5 $J Q S __. "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 0 r~ oo o 1 zz 1 § VO m O + rn O + fN + 1 ' + Oi — — • 1 | O O oo (— , ^ | _j_ | r-~ oo _2 ^ rn . *"" . Tt O O 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 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 *- _ + \ | 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 '2? 3J + 1> + + + + + + — •» 1 1 ro •'ti -^ 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 si c c a O O o OO GO D £ oo vo vo £ 3 & oj .22 -O .5 £•" | — — o o *1 1 c c c c eri 03 OO^ ~2 S — 0 o 2 ^ o o D (N — •* -C ^j o o ^ oj cl C § — O oo en J > i — m o O t/' V^ 0) ^" ^^ ^*. ^ "^ "" 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 & .^ ^^ ^^ t*^ f^^ o3 |M o o — o 0 O m ON O 03 — 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> 03 , ^* fN OJ £ c ^ .2 o -2 S £ o Si £ c •2 o C3 " p^ o a o . •2 < — 1 S 3 0. J .^ *o D. OJ 1/2 *> _ _ w 3 Q. ! o H ^-ooo O (« •55 m — t — oo ai S CN| 0 O O rr> ^ 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 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 O O — O ea > -) 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*!' > o o o ° \0 0 0 o 0 \C 0 O O > : •'.: o °o °0 lo 0 00 / o°0o f o n0 ° ° 0 oo0 O Q/ Fig. 38 Gastrocirrhus trichocystus, after Ito, 1958: (a) ventral surface; (b, c) ventral and dorsal surfaces showing trichocyst distribution. Genus EUPLOTASPIS Chatton & Seguela, 1936 Introduction Chatton & Seguela (1936) described a Euplotes-like hypotrich found in the branchial cavity of the sea squirt, dona intestinalis. They noted that the organisms were never observed on or around their host and they did not survive without their host for more than 36 hours in a medium which had been used successfully for the culture of many marine Euplotes. This species was found to have many characters similar to those of Euplotes but Chatton & Seguela (1936) noted that its body shape and very thick short cirri were more like those of Aspidisca. Furthermore, the AZM was entirely ventral so that it did not border the anterior dorsal surface as in Euplotes, and four of the frontoventral cirri were split into two parts which is a distinctive feature. Corliss (1961) placed this genus along with Paraeuplotes in the family Paraeuplotidae but later (Corliss, 1977) he transferred it to the family Aspidiscidae. REVIEW OF EUPLOTIDAE 233 Diagnosis of Euplotaspis Marine oval hypotrichs living in sea squirts. There is a prominent AZM restricted to the ventral surface. There are 9 frontoventral, 5 transverse and 3—4 caudal cirri. The four frontoventral cirri towards the right body border are split longitudinally into two parts. Macronucleus C-shaped. The dorsal argyrome is like that of Euplotes vannus (see Curds, 1975). Species description Euplotaspis cionaecola Chatton & Seguela, 1936 DESCRIPTION (Fig. 39). Euplotaspis cionaecola is a 60-70 um long marine hypotrich found in rv-'x ; \ ::..x A u ,/ /--T ,-(' 1A _^ ^ ri 4---"\- J !' * A ,.-\ f- v — 4 - ) — v- V""' i Fig. 39 Euplotaspis cionaecola, after Chatton & Seguela, 1936: (a) ventral surface of living cell; (b, c) ventral and dorsal surfaces of silver-impregnated specimens. 234 C. R. CURDS & I. C. H. WU the branchial cavity ofCiona intestinalis. The body outline is perfectly oval, convex dorsally and flattened or slightly concave ventrally. The AZM of about 50 membranelles, is a prominent band parallel to, and at a short distance from, the left body margin. There are 10 short, wide frontoventral cirri: the four on the right being split longitudinally. The 5 transverse cirri are separated by marked ridges on the ventral surface. The 3-4 caudal cirri are small and indistinct in vivo but can be seen in silver impregnated specimens. The dorsal silver-line system consists of 7-8 dorsal kinetics, each carrying about 1 5 cilia, with simple cross-links between the kinetics. The macronucleus is C-shaped and a single micronucleus has been observed at its posterior left. Genus EUPLOTIDIUM Noland, 1937 Introduction Noland (1937) described a hypotrich found in sponges from the Gulf of Mexico and stated that 'the organism differs from Euplotes, its nearest relative, in the absence of caudal cirri, and in the more cylindrical shape of the body'. Consequently, he erected the genus Euplotidium Noland, 1937 and called the organism Euplotidium agitatum Noland, 1937 because of its erratic movements. Ito (1958) also described a cylindrical Euplotes-\ike organism, but in this species there was one left caudal cirrus and more frontoventral and transverse cirri than in E. agitatum, this he called Euplotidium itoi Ito, 1958. A further species with different numbers of frontoventral and transverse cirri, Euplotidium arenarium Magagnini & Nobili, 1964, was later described and Borror (1972) transferred Euplotes psammophilus Vacelet, 1961 to the genus. More recently Hartwig (1980) added another species to the genus. Diagnosis of Euplotidium Small to large (65-200 um long) marine hypotrichs. Outline shape slightly elongated oval. Rounded in cross-section, never dorso ventrally flattened. The peristome is a wide funnel- shape with a prominent AZM that borders both the anterior semi-circular body edge and the left margin of the peristome. There are 7-12 frontoventral, 5-6 transverse and, when present, a reduced number (1-2) of caudal cirri. Key to the species of Euplotidium 1 With less than 10 frontoventral cirri 2 With 10 or more frontoventral cirri 4 2 With 9 frontoventral cirri but without caudal cirri E. agitatum With 7 frontoventral and 1 or 2 caudal cirri 3 3 With 1 caudal cirrus, macronucleus in many parts E. helgae With 2 caudal cirri, macronucleus elongate E. psammophilus 4 With 10 frontoventral and more than 1 caudal cirri E. arenarium With 12 frontoventrals and 1 caudal cirrus E. itoi Species descriptions Euplotidium agitatum Noland, 1937 DESCRIPTION (Fig. 40). This, the type species, is 65-95 um long and its cylindrical body shape is most apparent when viewed from the anterior. There is a funnel-shaped peristome which is lined around its anterior rim and left side by a prominent AZM. There are approximately 40 membranelles on the anterior part and about the same number in the REVIEW OF EUPLOTIDAE 235 Fig. 40 Euplotidium agitatum, after Noland, 1937: (a) ventral surface; (b) dorsal surface; (c) view from anterior showing cylindrical body. ventral part of the AZM. There are 9 frontoventral cirri, aligned in 2 rows, near the right body edge and 5 conspicuous transverse cirri but caudal cirri are not present. NOTE. Originally isolated from water squeezed from sponges in the Gulf of Mexico. Euplotidium itoi Ito, 1958 DESCRIPTION (Fig. 41). This is a medium sized (89-95 um long), cylindrical hypotrich with a slightly flattened ventral surface. The AZM borders the anterior and left edges of the peristome forming a sigmoid shape. Nine of the 12 frontoventral cirri are in 2 oblique rows situated near the anterior right of the peristome while the other 3 are scattered along the right body edge. There are 6 large transverse cirri and a single small left caudal cirrus. The macronucleus is in 2 ribbon-like parts with 4 micronuclei. NOTES. The position of the reorganisation band in Ito's (1958) diagram indicates that it could have been at some stage of division. Originally found in seaweed in the Inland Sea of Japan. Euplotidium arenarium Magagnini & Nobili, 1964 DESCRIPTION (Fig. 42). This is a medium sized (71-120 um long) oval species with a wide 236 C. R. CURDS & I. C. H. WU Fig. 41 Euplotidium itoi, after Ito, 1958. triangular peristome. The AZM consists of about 75 membranelles and it extends around the anterior semi-circular rim of the peristome down to the left side. There are 10 fron to ventral s, 5 transversals and a single left caudal cirrus. The transverse cirri are not conspicuous as in the other species of the genus and could be overlooked. The macronucleus is moniliform, in 5-10 pieces, and is curved towards the right. The silver-line system consists of 2 marginal kinetics confluent posteriorly and there are dorsal and ventral mesh-like argyromes. NOTE. Originally isolated from sand in the Gulf of Naples. Euplotidium psammophilus (Vacelet, 1961)Borror, 1972 Euplotes psammophilus Vacelet, 1 96 1 DESCRIPTION (Fig. 43). This is a large (125 urn long) species in which the wide peristome extends about two-thirds down the length of the body. There are 7 frontoventral cirri arranged in 2 groups on the right of the peristome. Three are closely packed together at the anterior and 4 are in a row behind them. The 5 transverse cirri are long and there are 2 caudal cirri. Vacelet (1961) also described the presence of a row of short cilia along the posterior right body edge. The elongated curved macronucleus is rod-like with an adjacent micronucleus. NOTES. This was originally described as a species of Euplotes', Borror (1972) transferred it to Euplotidium on account of the shape of the body and peristome and because of the reduced number of caudal cirri. Euplotidium helgae Hart wig, 1980 DESCRIPTION (Fig. 44). This is the largest (up to 200 urn long) of the species. The peristome Fig. 42 Euplotidium arenarium, after Magagnini & Nobili, 1964; (a) ventral surface of living cell; (b, c) ventral and dorsal surfaces of silver-impregnated specimens; (d) stages in nuclear reorganisation. 238 C. R. CURDS & I. C. H. WU 20iim Fig. 43 Euplotidium psammophilus, after Vacelet, 1961 (called Euplotes psammophilus): (a) ventral surface; (b) nuclear apparatus. 50yu m Fig. 44 Euplotidium helgae, after Hartwig, 1 980. extends about two-thirds down the body length. The original author (Hartwig, 1980) was not too sure about the cirral pattern and the interpretation used here is based on the assumption that there are 5 transverse and 7 frontoventral cirri rather than 4 transverse and 8 frontoventral cirri. There is a single caudal cirrus on the left and the fronto ventral s are arranged in a single group on the right of the peristome. The macronucleus consists of 1 1 oval parts arranged in the shape of the letter C. There are several micronuclei. NOTE. Originally found in sand in Bermuda. REVIEW OF EUPLOTIDAE Genus PARAEUPLOTES Wichlerman, 1942 239 Introduction Wichterman (1942) described a hypotrichous ciliate which he found in abundance on the coral Eunicea crassa in the Tortugas. The species resembled Euplotes in that it had a well developed AZM and a C-shaped macronucleus, but its rather peculiar ciliature bore no resemblance to that of Euplotes. He called the genus Paraeuplotes Wichterman, 1942 and placed it in a new family, the Paraeuplotidae Wichterman, 1942. Here, following Horror (1972) and Corliss (1977) the genus is provisionally included in the Euplotidae. Diagnosis of Paraeuplotes Discoid marine hypotrich with a well-developed AZM which originates on the dorsal surface and curves down three-quarters of the body length on the ventral surface. Undulating membrane absent. There are no marginal cirri but there is a small group of short caudal cirri. There is an extensive arc of transverse cirri parallel with the right body edge. Anteriorly, there is an arc of cilia parallel with the apical body edge and an isolated pair of cirri in the midventral position. The macronucleus is C-shaped. Contains numerous zooxanthellae. 20>um Fig. 45 Paraeuplotes tortugensis, after Wichterman, 1942: (a) ventral surface; (b) dorsal surface; (c) nucleus. 240 C. R. CURDS & I. C. H. WU Species description Paraeuplotes tortugensis Wichterman, 1942 DESCRIPTION (Fig. 45). Small to medium discoid species measuring on average 80 um in diameter. The well-developed AZM forms a collar-like structure on the anterior dorsal surface which extends ventrally down about three-quarters of the body length. There is no undulating membrane present. Anteriorly there is an arc of cilia parallel with the body edge and a pair of isolated cirri lying in a midventral position. There is an extensive arc of transverse cirri parallel with the right body edge and a group of 5-6 short caudal cirri slightly to the right of the posterior body pole. The macronucleus is C-shaped. The cell is packed with numerous yellow-brown zooxanthellae. NOTE. Originally isolated from the coral Eunice crassa in the Tortugas. Genus SWEDMARKIA Dragesco, 1954 Introduction Dragesco (1954, 1960, 1965) studied and described this genus over a period of several years. He (Dragesco, 1960, 1965) likened the genus to Euplotidium and Gastrocirrhus and considered it to be a possible evolutionary link between the Holostichidae Faure-Fremiet, 1961 and the Euplotidae. Both Faure-Fremiet (1961) and Corliss (1977) placed Swedmarkia in the family Gastrocirrhidae but it is here provisionally included in the Euplotidae. Diagnosis of Swedmarkia Medium sized (100-1 10 jim long) marine hypotrichs with conspicuous AZM arranged around a wide triangular peristome. There are two particularly long membranelles at the left of the apex of the peristome. A wide undulating membrane lies on the right of the peristome. There are many (54-58) cirri present with the following distribution. Numerous frontoventrals include a row along the right peristome edge, an apical group and an irregular midventral row. There are 5 large transverse and rows of right and left marginal cirri that are confluent posteriorly. The macronucleus is divided into numerous (about 100) portions and there are 5-9 micronuclei. Species description Swedmarkia arenicola Dragesco, 1954 DESCRIPTION (Fig. 46). This is a medium sized (100-1 10 urn long) marine hypotrich, similar in shape to Euplotes. The body is oval to triangular in shape and there is a large triangular peristome which extends down three-quarters of the body length where it occupies about half of the ventral surface. The AZM consists of 54-68 membranelles of which two, at the extreme left apex of the peristome, are particularly long. There is a wide undulating membrane on the right peristome border. The total of 54-58 cirri are arranged as follows, a row of fron to ventral (peristomial) cirri is spaced evenly along the right peristomial edge. A group of 6 frontoventral cirri are situated around the extreme apex of the cell and there is an irregular row of 5 frontoventrals lying in the midventral position. Additionally, a short row of left marginal cirri is present with an irregularly spaced row of right marginals, of which the anterior half arise from the dorsal surface. The marginals are continuous along the posterior border. The macronucleus is divided into numerous (about 100) spherical pieces and there are 5-9 micronuclei. The three dorsal kinetics bearing double cilia are illustrated in Fig. 46b. REVIEW OF EUPLOTIDAE 241 Fig. 46 Swedmarkia arenicola, after Dragesco, 1965: (a) ventral surface; (b) dorsal surface; (c, d) ventral surface showing variations in form, number and arrangement of certain cirri. 242 C. R. CURDS & I. C. H. WU Genus GRUBERELLA (Gruber, 1884) Corliss, 1960 Stylocoma Gruber, 1 884 Introduction Gruber (1884) described the marine hypotrich Stylocoma oviformis Gruber, 1884 which Kahl (1932) redescribed and placed in the family Euplotidae. Soon after, another species, Stylocoma adriatica Kiesselbach, 1936, which lacked transverse cirri, was described. Corliss (1960) pointed out that the generic name was preoccupied by Stylocoma Lioy, 1864 a dipteran insect, and proposed that it should be replaced by Gruberella Corliss, 1960. Borror (1972) considered the genus to be of questionable status but Corliss (1977) included it as an incertae sedis in the Sporadotrichina. Here, the genus is provisionally included in the Euplotidae on account of its funnel-like peristome, which is reminiscent of Gastrocirrhus, and the arrangement of cirri which, although reduced, are more like those in the Euplotidae than in any other family of hypotrichs. Diagnosis of Gruberella Ovoid, marine hypotrichs, rounded in cross-section. There is a centrally placed funnel- shaped peristome bordered by a conspicuous AZM anteriorly and down the left side. Cirri reduced. Caudal cirri present, transverse cirri may or may not be present. Frontoventral and marginal cirri absent. Macronucleus in two parts. Key to the species of Gruberella 1 With 6 caudal and 7 transverse cirri . With 6 caudal but without transverse cirri G. oviformis G. adriatica Species descriptions Gruberella oviformis (Gruber, 1 884) Corliss, 1960 Stylocoma oviformis Gruber, 1 884 DESCRIPTION (Fig. 47). Ovoid marine hypotrich with wide, centrally placed, funnel-shaped peristome which has a slightly raised edge forming an anterior collar-like region. The Fig. 47 Gruberella oviformis: (a) after Gruber, 1 884; (b) after Kisselbach, 1936. REVIEW OF EUPLOTIDAE 243 prominent AZM consisting of many large membranelles originates on the ventral surface on the right of the peristome and continues around the apex down the left side. There are only 2 groups of cirri, 7 transverse and 6 long caudal cirri. No frontoventral or marginal cirri are present. Shape of macronucleus unrecorded. Gmberella adriatica (Kisselbach, 1936) Corliss, 1960 Stylocoma adriatica Kiesselbach, 1936 DESCRIPTION (Fig. 48). Medium sized (80 um long) triangular shaped marine hypotrich with funnel-shaped, centrally positioned peristome. Prominent AZM borders the anterior and left peristomial edges. Cirri reduced to a single group of 6 long caudals. There are no transverse, frontoventral or marginal cirri present. Macronucleus divided into 2 ovoid pieces with a micronucleus between the pair. Fig. 48 Gruberella adriatica, after Kisselbach, 1 936. Genus CYATHAROIDESTuffrau, 1975 Introduction Tuffrau (1975) described a species from Antarctica which closely resembled Euplotes in certain respects but not in others. It is characterised by the presence of a row of 12 large right marginal cirri in addition to the usual frontoventral and transverse cirri. Furthermore, there is an extensive paroral membrane composed of a single kinety of long cilia which is unlike the undulating membrane of Euplotes and there is also endoral ciliature which is not found in Euplotes. Diagnosis of Cyatharoides Irregularly oval marine hypotrich with a very large peristomial funnel occupying much of the ventral surface onto which it opens. The peristome is surrounded by a collar-like swelling of the anterior left body edge, with a characteristic 'niche' or invagination of the right anterior peristome region. The AZM is composed of many membranelles lining the left peristomial border. On the right, at the bottom of the peristomial funnel there is a paroral membrane composed of a single kinety of long cilia and an arc of endoral cilia. There are 10 frontoventral, 5 transverse and a row of 1 2 right marginal cirri along the right body edge. Dorsally there are 12-26 kinetics of cilia and the macronucleus is C-shaped. 244 C. R. CURDS & I. C. H. WU Species description Cyatharoides balechi Tuffrau, 1 975 DESCRIPTION (Fig. 49). Irregularly oval, large (140-200 urn long) marine, planktonic hypotrich with a very large peristomial funnel opening over much of the ventral cell surface. Anteriorly the peristome is surrounded by a collar-like swollen ridge of the anterior left body edge, with a characteristic invagination of the peristome on the right anterior edge. The AZM is prominent and composed of many large membranelles. There are paroral and endoral membranes on the posterior right peristomial edge. With 10 frontoventral, 5 transverse and 12 right marginal cirri. Dorsal surface with 12-26 kinetics of many cilia. Macronucleus large, open C-shaped. NOTE. Originally isolated from plankton sample taken from Antarctic Ocean near base of Argentina by Prof. Balech. Mr Fig. 49 Cyatharoides balechi, ventral surface, after Tuffrau, 1975. References Agamaliev, F. G. 1967. Faune des cilies mesopsammiques de la cote ouest de la Mer Caspienne. Cah. Biol. mar. 8 : 359^02. 1 968. 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Some ciliates from Tortugas. Pap. Tortugas Lab. 32 : 179-222. Biitschli, O. 1887-1889. Protozoa. Abt III. Infusoria und System der Radiolaria. In Bronn, H. G. (Ed.), Klassen und Ordnungdes Thiers-Reichs Vol. 1 , pp. 1098-2035. Leipzig, C. F. Winter. Calkins, G. N. 1902. Marine protozoa from Woods Hole. Bull. U.S. Fish Comm. 21 (yr 1901): 41 3-468. 1911. Regeneration and cell division in Uronychia. J. exp. Zool. 10 : 95-1 16. Chatton, E. & Lwoff, A. 1930. Impregnation par diffusion argentique de 1'infraciliature des cilies marins et d'eau douce apres fixation cytologique et sans dessication. C. r. Seanc. Soc. Biol. 104 : 834-836. Chatton, E. & Seguela, J. 1936. Un hypotriche de la branchie de dona intestinalis L., intermediaire entre les Euplotidae et les Aspidiscidae: Euplotaspis cionaecola n.g., n.sp. Bull. Soc. zool. Fr. 61 : 332-340. Claparede, E. & Lachmann, J. 1858 (1857). Etudes sur les infusoires et les rhizopodes. Mem. Inst. natn. genev. 5 : 1-260. Corliss, J. O. 1960. 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Complements a la connaissance des cilies mesopsammiques de RoscofF. II. Heterotriches III. Hypotriches. Cah. Biol. mar. 4 : 251-275. 1965. Complements a la connaissance de Swedmarkia arenicola et Discocephalus ehrenbergi cilies hypotriches. Anneebiol. 4 : 187-204. 1968. Metopus jankowskii n.sp., Sonderia sinuata Kahl et Discocephalus minimus n.sp. cilies nouveaux ou mal connus. Annls Fac. Sci. Univ. fed. Cameroun 1 : 77-£ Dujardin, F. 1841. Histoire Naturelle des Zoophytes Infusoires. 678 pp. Paris. Ehrenberg, C. G. 1830 (1832). Beitrage zur Kenntriis der Organisation der Infusorien und ihrer geographischen Verbreitung, besonders in Siberien. Abh. Akad. Wiss. DDR year 1832 : 1-88. 1831 (1832). Uber die Entwicklung und Lebendauer der fnfusionsthiere; nebst ferneren Beitragen zu einer Vergleichung ihrer organischen Systeme. Abh. Akad. Wiss. DDR year 1832 : 1-1 54. 1838. Die Infusionsthierchen als Vollkommene Organismen.6\2 pp. Leipzig. Fabre-Domergue, P. L. 1885. Note sur les infusoires cilies de la baie de Concarneau. /. Anal. Physioi, Paris 21 -.554-56%. Faure-Fremiet, E. 1954. Gastrocirrhus adhaerens n.sp. Anais Acad. bras. Cienc. 26 : 163-168. 1961. Remarques sur la morphologie comparee et la sytematique des ciliata Hypotrichida. C.r. hebd. Seanc. Acad. Sci., Paris 252 : 35 1 5-3519. Fenchel, T. 1965. Ciliates from Scandinavian molluscs. Ophelia 2:71-1 74. Fresenius, G. 1865. Die Infusorien des Seewasseraquariums. Zool. Gart., Frankf. 6 (3): 8 1-89. 6(4): 121-129. Gruber, A. 1884. Die Protozoen des Hafens von Genua. Nova Acta Acad. Caesar. Leop. Carol. 46 : 473-539. 246 C. R. CURDS & I.C. H. WU Hartwig, E. 1973. Die Ciliaten des Gezeiten-Sandstrandes der Nordseeinsel Sylt. 1. Systematik. Mikrofauna Meeresbodens 18 : 1-69. 1974. Verzeichnis der im Bereich der deutschen Meereskiiste angetroffenen interstitiellen ciliaten. Mitt. hamb. zool. Mus. Inst. 71 : 7-21. The interstitial ciliates of Bermuda with notes on their geographical distribution and habitat. Cah. Biol.mar.2l : 409-441. Hartwig, E. & Parker, J. G. 1977. On the systematics and ecology of interstitial ciliates of sandy beaches in North Yorkshire. J. mar. biol. Ass. U.K. 57 : 735-760. Hemprich, F. G. & Ehrenberg, C. G. 1828 (1831). Animalia Evertebrata exclusis Insectis. In Symbolae Physicae seu Iconis et Descriptiones Animalium Evertebratorum Sepositis Insectis. 126 pp. Berolini ex officina Academica. (date of plates 1 828). 1831. Animalia Evertebrata exclusis Insectis. In Symbolae Physicae seu Iconis et Descriptiones Animalium Evertebratorum Sepositis Insectis. 126 pp. Berolini ex officina Academica. (date of text 1831). Ito, S. 1958. Two new species of marine ciliates Euplotidium itoi sp.nov., and Gastrocirrhus trichocystus sp.nov. Zool. Mag. Tokyo 61 : 184-187. 1963. Cytological observations of nuclear behavior in the conjugation of Diophrys scutum. Zool. Mag. Tokyo 72: 230-234. Kahl, A. 1932. Urtiere oder Protozoa. I. Wimpertiere oder Ciliata (Infusoria), eine Bearbeitung der freilebenden und ectocommensalen Infusorien der Erde, unter Anschluss der marinen Tintinnidae. 3. Spirotricha. In Dahl, F. (Ed.), Die Tierwelt Deutschlands, pt. 25 : 399-650. G. Fischer, Jena. Kattar, M. R. 1970. Estudo dos protozoarios ciliados psamofilos do litoral Brasileiro. Bolm Fac. Filos. Cienc. Univ. S. Paulo Zool. Biol. mar. NS21 : 123-206. Kent, W. S. 1880-1882. A Manual of the Infusoria. Vols 1-3: 913 pp. David Bogue, London. Kisselbach, A. 1936. Zur Ciliatenfauna der Nordlichen Adria. Thalassia2(5): 1-53. Lepsi, J. 1928. Un nouveau protozoaire marin; Gastrocirrhus intermedium. Annls Protist. 1 : 195-197. Lioy, P. 1864. I ditteri distribuiti secundo un nuovo metodo di classificazione naturale. Atti 1st. veneto Sci. Ser. 3.9(2) : 989-1 126. Magagnini, G. & Nobili, R. 1964. Su Euplotes woodruffi Gaw e su Euplotidium arenarium n.sp. (Ciliatea, Hypotrichida). Monitore zool. ital. 12 : 1 78-202. Mansfeld, K. 1923. 16 neue oder wenig bekannte marine Infusorien. Arch. Protistenk. 46 : 97-140. Miiller, O. F. 1 786. Animalcula Infusoria Fluviatilia et Marine. 367 pp. Havniae et Lipsiae. Noland, L. E. 1937. Observations on marine ciliates of the gulf coast of Florida. Trans. Am. microsc. Soc.56: 160-171. Ozaki, Y. & Yagui, R. 1942. A new marine ciliate Cirrhogaster monilifer n.g. n.sp. Annotns zool. jap. 21:79-81. Pierantoni, N. 1909. Su alcuni Euplotidae del Golfo di Napoli. Boll. Soc. Nat. Napoli 1909 : 53-64. Quennerstedt, A. 1867. Bidragtill a Sveriges Infusorie-fauna. Ada Univ. lund. 4 : 1-47. Raikov, I. B. & Kovaleva, V. G. 1968. Complements to the fauna of psammobiotic ciliates of the Japan Sea (Posjet Gulf). Ada Protozool. 6 (27) : 309-333. Rees, J. van 1881. Zur Kenntnis der Bewimperung der Hypotrichen Ifusorien, nach Beobachtungen an Styloplotes grandis n.sp. und Euplotes longipes Claparede & Lachmann. Ellerman & Harms, Amsterdam. 1883-1884. Protozoaires de 1'escautde Test. Tijdschr. ned. dierk. Vereen. Suppl. 1 : 592-673. Reiff, I. 1968. Die genetische Determination mutlipler Paarungstypen bei dem Ciliaten Uronychia transfuga (Hypotricha, Euplotidae). Arch. Protistenk. 110 : 372-397. Ruinen, J. 1938. Notizen uber Ciliaten aus konzentrierten Salzgewassern. Zool. Meded. 20 : 243-256. Sauerbrey, E. 1928. Beobachtungen uber einige neue oder wenig bekannte marine Ciliaten. Arch. Protistenk. 62 : 355-407. Stein, F. 18590. Der Organismus der Infusionsthiere nach eigenen Forsuchungen in Systematischer Reihenfolge Bearbeitet I. 206 pp. Leipzig. 185%. Charakteristik neuer Infusoriengattungen. Lotos 9 : 2-5. 9 : 57-60. Summers, F. M. 1935. The division and reorganization of the macronuclei of Aspidisca lynceus Miiller, Diophrys appendiculata Stein, and Stylonychia pustulata Ehrbg. Arch. Protistenk. 85: 173-208. Taylor, C. V. 1928. Protoplasmic reorganization of Uronychia uncinata sp.nov. during binary fission and regeneration. Physiol. Zool. 1(1): 1-25. Tuffrau, M. 1975 (1974). Un nouvel Euplotidae: Cyatharoides balechi, n.g., n.sp., cilie Hypotriche de 1'Anarctique. Prostistologica 10 (3) : 31 1-317. REVIEW OF EUPLOTIDAE 247 Vacelet, E. 1960. Note preliminaire sur la faune infusorienne des 'Sables a Amphioxus' de la biae de Marseille. Reel Trav. Stn mar. Endoume33 (9) : 53-57. 1961. La faune infusorienne des 'Sables a Amphioxus' des environs de Marseille. Bull. Inst. oceanogr. Monaco 3 (\202) : 1-12. Wallengren, J. 1901 (1900). Zur Kenntnis der vergleichenden Morphologic der hypotrichen Infusorien. Bih. K. svenska VetenskAkad. Handi 26 (4) : 1-31. Wichterman, R. 1942. A new ciliate from coral of Tortugas and its symbiotic Zooanthellae. Pap. Tortugas Lab. 33 : 107-111. Wu, I. C. H. & Curds, C. R. 1979. A guide to the species ofAspidisca. Bull. Br. Mus. nat. Hist. (Zool.) 36(1): 1-34. Young, D. B. 1922. A contribution to the morphology and physiology of the genus Uronvchia. J. exp. Zool. 36 : 353-395. Manuscript received for publication 4 August 1982 Index to Species (Names given in roman refer to synonyms) Campylopus paradoxus 220 Certesia ovata 228 quadrinucleata 228 Cirrhogaster monilifer 23 1 Cyatharoides balechi 244 Discocephalus ehrenbergi 195 grandis 195 minimus 197 rotator ius 194 rotatorius 195 Diophrys appendiculata 203 appendiculatus 203 grandis 206 hystrix 207 irmgard2Ql kahli 209 kasymovi 206 magnus 206 marina 203 multinucleata2\5 oligothrix 2 1 0 peloetes 2 1 0 quadricaudatus 2 1 1 salina 209 scutoides 2 1 2 scutum 203 tetramacronucleata 2 1 4 Euplotaspis cionaecola 233 Euplotes psammophilus 236 Euplotidium agitatum 234 arenarium 235 Helgae236 /to/ 23 5 psammophilus 236 Gastrocirrhus adhaerens 230 intermedius 229 monilifer 231 stentoreus 229 trichocystus23\ Gruberella adriatica 243 oviformis 242 Paraeuplotes tortugensis 240 Planiplotes wagneri 203 Ploesconia scutum 203, 222 Polycoccon octangulus 194 Schizopus norwegicus 203 Stylocoma adratica 243 oviformis 242 Stylonychia appendiculata 203 Styloplotes appendiculatus 203 appendiculatus var pontica 203 fresenii 203 grandis 206 norwegicus 206 quennerstedti 206 Swedmarkia arenicola 240 Trichoda transfuga 220 Uronvchia binucleata 226 bivalvorum 220 heinrothi 220 magna 226 setigera 225 transfuga 220 uncinata220 British Museum (Natural History) An Atlas of Freshwater Testate Amoebae C. G. Ogden & R. H. Hedley 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) The Ophthalmotilapia assemblage of tichlid fishes reconsidered Peter Humphry Greenwood Zoology series Vol 44 No 4 28 April 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.) A) is unique to the Ophthalmotilapia assemblage. The gap is created, in part, by a reduction in the depth of the entopterygoid, and in part by a reduction of its extension above the quadrate. As a. result of these proportional and positional changes, the anterior entopterygoidal margin lies below the level of the palatine's posterior margin, and below the upper part of the ectopterygoid as well (with both of which bones it would otherwise articulate). The space between the three bones (that is, the 'gap') is actually filled by dense, translucent connective tissue. 256 P. H. GREENWOOD It could be argued (and has been argued by Barel, pers. comm.} that the palatopterygoid gap is a correlate of the large and often ovoid eye characterizing all members of the OA. This is a complex problem to resolve since the influence of eye size and shape on cranial architecture is the result of several interacting factors, and there are few data available on the dynamics of syncranial ontogeny. In particular we have no information on the influence of ultimate eye size on the ontogeny of the whole suspensorium, of which the palatine and entopterygoid bones are but a part (see below p. 257). Taking the maximum diameter of the eye (expressed as a proportion of head length) as a measure of eye size it is difficult to find a simple correlation between that ratio and the nature of the palatine-entopterygoid articulation. For example, in Hemibates, Trematocara, Reganochromis, certain ' 'Limnochromis'' species and in Perissodus (all from Lake Tanganyika) the eye is as large as that in members of the OA, and the eye in Trematocara is as markedly ovoid as it is in any member of the OA. Yet, in none of these species is there a palatopterygoid gap. (Recently, Poll (1981) has revised the genus Limnochromis which he now divides into four genera. Since several of the older references in the literature are just to the genus Limnochromis, I have adopted the convention of referring to the taxon as 'Limnochromis', except when reference is made to species retained by Poll (1981) in that genus.) Conversely, in many species of the Malawian genus Lethrinops (Fig. 15) there is a palatopterygoid gap (albeit a less extensive one than in some though not all OA species), but the eye is smaller than in members of the OA. Since, amongst the taxa with enlarged eyes only the OA species have developed a palatopterygoid gap, the gap would seem to be a shared derived character for the assemblage. That argument would hold even if future research shows the 'gap' to be one of several correlated features associated with the evolution of a large eye. The presence of a gap in Lethrinops (which does not have enlarged eyes), on the other hand, fails to support any argument suggesting that eye size and a palatopterygoid gap are necessarily correlated. (2) [3]. The slender hyomandibula has a long symplectic process and no, or a very reduced, hyomandibular flange. On the basis of extensive outgroup comparisons I cannot agree with Liem on the relative length of the symplectic process. In fact, most OA species have a process which is no longer than that in Astatotilapia burtoni, A. elegans (or in other Astatotilapia species), or that in other Tanganyika genera (Fig. 2). Unfortunately this character is difficult to quantify and is one affected by the level to which the anterior margin of the hyomandibular flange is produced ventrally. To this extent the apparent length of the process is an optical illusion. It is also affected by the stoutness of the flange which, in this region of the bone, is easily damaged; if partially broken its absence may add to the apparent length of the symplectic process. As compared with the hyomandibular flange in many taxa (both within and outside Lake Tanganyika) that in all OA species is reduced. But, I would question that it is ever absent, even in those species with the greatest reduction in flange area. A reduction in flange area comparable with that found in OA species does occur in several other species as well, and these are mostly taxa with large eyes. Thus, amongst the Lake Tanganyika endemics a reduced OA-like flange is found in Hemibates, Trematocara, Haplotaxodon, Grammatotria, Callochromis, Xenotilapia, Cardiopharynx, Cyathopharynx and Aulonocara. In contrast, Reganochromis calliurus, whose eye is as large as that in some OA species, has a moderately well-developed flange which is larger than that in any OA species. The hyomandibular flange is not reduced in Lethrinops (Lake Malawi) nor in any of the species examined whose modal eye size (i.e. eye diameter as a proportion of head length) is less than that of any OA species. THE OPHTHALMOTILAPIA ASSEMBLAGE OF CICHLID FISHES 257 i mm Fig. 2 Hyomandibula (right), in lateral view, of: A, Ectodus descampsi; B, Astatotilapia macropsoides. There is thus some suggestion that a reduction in hyomandibular flange area may be correlated with a large eye size. This correlation could result, ontogenetically, from the developing eye preempting some of the space which otherwise would be available for the levator arcus palatini muscle whose origin is principally from the flange. It is noteworthy that in those species with a reduced flange, the levator arcus palatini has, relatively speaking, a reduced volume, and that its origin has shifted largely to the metapterygoid (Liem, 1981 : 19 5-6; personal observations). Incidentally (pace Liem, 1981 : 207), in three of the four Oreochromis niloticus specimens examined, hyomandibular flange area is proportionately equivalent to that in the OA species; in the fourth specimen it is noticeably larger. The two smallest O. niloticus (ca. 42 and 52 mm standard length) have the narrowest flanges of the four specimens examined, again suggesting that flange area may be related to eye size since the smallest fishes have proportionately the largest eyes. (3) [5] The vertical depth of the metapterygoid is shallow. It is difficult to assess the value of this character as an indicator of phyletic relationships. The metapterygoid is noticeably shallow in all the OA species recognized by Liem, and in those which I would add to the assemblage. However, an equally shallow or even shallower metapterygoid is known from several Tanganyika taxa (for example, in species of Lamprologus, Reganochromis, Trematocara, 'Limnochromis', and also in Perissodus hecqui, P. microlepis and P. eccentricus). In some of these species the eye is large (equivalent in size to those of the OA species), in others it is smaller. From this information it is impossible to decide whether a shallow metapterygoid is a correlate of eye enlargement, a homoplastic feature, or one which might be indicative of phyletic relationship at a higher level than that under consideration. (4) [2] The posterior and dorsal margins of the palatine form a 90° angle. Elsewhere, Liem (1981: 206) expands this statement and notes that The 90° posterodorsal angle surrounding a posterodorsal expansion of the palatine is not found in any other Tanganyika cichlids and deviates from the condition in generalized cichlids (e.g. Astatotilapia burtoni, Liem and Osse, 1975 and A. elegans, Barel, et al, 1976).' 258 P. H. GREENWOOD Liem (1981 : 208) places particular importance on this character, considering it as possibly the only autapomorphic feature of the assemblage. My observations on the OA species indicate that the posterodorsal angle is not always rectangular and that it shows some intra- and interspecific variability. Also, I would contest the statement that the OA type of palatine shape is not found in other Tanganyika species. It does occur, for example, in Limnochromis abeelei, and is closely approached in other species as well. Furthermore it occurs in species outside the lake (e.g. Astatotilapia macropsoides [Lakes Edward and George] and in some Lethrinops species [Lake Malawi]). I would agree, however, that the overall type of palatine morphology in OA species is relatively uncommon amongst African cichlids, combining as it does a straight or virtually straight posterior margin meeting the dorsal margin at, or almost at, an angle of 90°, and with a posteriorly expanded body of the bone. In combination these features give to the elongate vertical part of the bone a distinctive and near rectangular outline. Like character (3) [5], the palatine shape is difficult to evaluate as an indicator, or potential indicator, of close phylogenetic relationship. However, since a similarly shaped bone is rarely present amongst taxa other than members of the OA (and in those genera where it does occur it is not manifest by all member species), and since non-OA taxa with this type of palatine are not closely related to the OA, it might well indicate a shared common ancestry for the Ophthalmotilapia assemblage. (5) [4]. The anterior margin of the pterosphenoid is notched. This character is so widely distributed amongst African cichlids (including the most generalized taxa) that it cannot be treated as an apomorphy at this level of phyletic analysis. That the notch, or rather the tongue which delimits one aspect of the notch, has not been commented upon before, or been shown in figures of cichlid neurocrania, may well be due to its fragility and hence loss during preparation of the skull. (It is of course absent in some species and is not invariably present in all members of a genus.) Also, the process can be rather small and is then virtually invisible unless the skull is carefully cleaned of connective tissue. Pace Liem (1981 : 207), the ligament connecting the sclerea with the pterosphenoid or its notch is present in generalized cichlids. In fact, it is present in all the cichlids I have dissected, and also in several other teleostean groups as well (including non-percoids). (6) Liem's two myological characters, viz. [7] the transversus dorsalis is reduced, and [8] the obliquus posterior is enlarged, may be taken together. At the outset of any discussion it must be made clear that neither character is easily assessed, partly because of insufficient comparative data from outgroups, and partly because they are not readily quantified and are thus particularly subjective. In the discussion which follows, Asprotilapia is excluded from any generalizations about the transversus dorsalis in the OA; Asprotilapia does show unequivocally clear-cut reduction of the transversus dorsalis anterior and the posterior head of the muscle is not developed at all. From my observations on dorsal gill-arch muscles in OA taxa, and in other cichlids from Tanganyika and elsewhere (including generalized species such as Astatotilapia elegans, and 'derived' taxa such as Bathybates, Hemibates and Trematocara (see also Stiassny, 1981), I would not consider the condition of the transversus dorsalis or the obliquus posterior in OA species to be trenchantly distinct. For example, although Liem (1981 : 207) considers the transversus dorsalis complex in OA species to be reduced relative to that in A. elegans, and the obliquus posterior to be hypertrophied, I could see no obvious differences when making the same comparisons. That there are differences in the extent to which these and other dorsal gill-arch muscles are developed amongst African cichlids cannot be denied (see for example Liem, 1973; Liem & Osse, 1975; Stiassny, 1981). But, the differences are rarely trenchant and in some cases THE OPHTHALMOT1LAPIA ASSEMBLAGE OF CICHLID FISHES 259 (including manifestly trenchant ones) are the result of environmentally induced individual variations (see Liem & Osse, 1975 : 442, fig. 11; for environmental effects, see Greenwood 1965). Thus, until considerably more comparative data are available, and until some means of quantifying apparent differences is employed, the use of relative muscle size would seem to be of very limited value, and could even be misleading. For those reasons I would not use either of the muscle characters in attempting to unravel the phylogeny of the OA (except, as noted earlier, with regard to Asprotilapia; see below, p. 263). (7) [6] The operculum has a distinct auricular process. Although Liem (1981 : 207) notes that a well-developed auricular process occurs on the operculum in several taxa, it is only in Perissodus hecqui, 'Limnochromis' dhanisi and the six genera now included in the OA (see p. 262) that I would consider the process equivalent to that found in the OA species. In all members of the assemblage, the opercular process, although interspecifically variable in form and size, is always a noticeable feature of the bone. That fact, coupled with the infrequent occurrence of a distinct process amongst other genera (and its mosaic interspecific distribution in those taxa), would seem to enhance its value as an indicator of monophyletic origin for the OA. In brief, of the eight supposedly apomorphic characters cited by Liem as suggesting a monophyletic origin for the OA, only three would seem to fulfil the necessary requirements for such features, and then mainly because of their unique congruence in the species con- cerned. The characters, as numbered above, are: the palatopterygoid gap (1), the morphology of the palatine bone (4), and the presence of an auricular process on the posterodorsal margin of the operculum (7). The remaining characters (i.e. 2, 3, 5 & 6) are either of no value, are possible homoplasies, or cannot be fully evaluated within the scope of our present knowledge. There are, however, two other characters noted by Liem, and used by him at a different level of universality (the intragroup level), which I consider to be group apomorphies for the whole assemblage. These are: (8) [15] The morphology of the lachrymal (1st infraorbital) bone. The lachrymal in members of the OA has a very distinctive appearance (see Liem, 1981, fig. 5; and Figs 3A-H), one which, apparently, is not replicated in any other African cichlid. It differs from the generalized condition (as seen, for example, in Astatotilapia macropsoides, Fig. 3J) in its overall protraction and relative shallowness. Because the anterior portion is noticeably deeper than the posterior part, the bone has almost the appearance of a short but deep handle extending from its expanded and near rhomboidal anterior region (Figs 3A-H); although the anterior region is much deeper than the posterior part, it is by no means as expansive as it is in the majority of African cichlids. An elongate lachrymal occurs in a few other taxa (e.g. certain 'Limnochromis' species; Fig. 31) but here the bone is uniformly protracted and so lacks the contrast between its shallower posterior third to half and the deeper anterior part, which is so characteristic of the OA type lachrymal. Also, in these non-OA taxa with an elongate, or relatively elongate lachrymal, the dorsal margin of the bone is but slightly concave, whereas in the OA species it is markedly so. The anterior margin of the lachrymal is straight or very slightly concave, its anteroventral angle produced into a slight but distinctive peak (which is lacking in most species with an elongate lachrymal but is present in some, e.g, 'Limnochromis' permaxillaris and 'L'. pfefferi). When the bone is in situ its anterior margin slopes upwards at an angle of 50°-60° to the horizontal (the 'modal' slope in African cichlids would seem to be one close to the horizontal, but there are several and apparently unrelated species where the slope is between 45° and 60°). 260 P. H. GREENWOOD Fig. 3 Lachrymal (left), in lateral view, of: A, Cyathopharynx furcifer; B, Callochromis macrops melanostigma; C, Xenotilapia tenuicaudata; D, Xenotilapia boulengeri; E, Grammatotria lemairei; F, Cyathopharynx schoutedeni (see p. 282); G, Asprotilapia leptura; H, Aulonocranus dewindti: I, Limnochromis auritus; J, Astatotilapia macropsoides. Liem's figure of the OA species Cunningtonia longiventralis (and his comments on the bone, Liem, 1981 : 206, fig. 5C) represents an unusual condition in that species since the anterior lachrymal margin is shown as markedly concave and aligned almost horizontally. In all 12 specimens I examined, the orientation of the bone and the shape of its anterior margin (including the anteroventral peak) are typically of the OA type (see Fig. 4). There are, with very few individual exceptions, six lateral line canal pores in the lachrymal of OA species (but see p. 263 below). The modal number of these pores in all African cichlids is five; the occasional departure from that number seems to be attributable to individual variability. Thus, both in its outline shape (including the anteroventral peak) and in having six lateral line pores, the lachrymal appears to be a unique apomorphic feature for the OA. Liem (1981 : 208) used the presence of an anteroventral peak on the lachrymal as a synapomorphy differentiating Ectodus, Lestradea, Ophthalmotilapia and Cunningtonia from Asprotilapia which, by implication, lacked this process. In the three specimens of Asprotilapia leptura (the sole species) I examined, a typical OA peak is present and the outline shape of the bone also conforms with that of other OA species (see Fig. 3G). THE OPHTHALMOT1LAPIA ASSEMBLAGE OF CICHLID FISHES 261 omm Fig. 4. Cunningtonia longiventralis, left lateral view of lachrymal in situ. (9) [9]. The presence on the anguloarticular bone of a well-developed, anteroposteriorly aligned fossa for the insertion of the adductor mandibulae muscle A2. This well-developed fossa is noted by Liem (1981 : 195) in his anatomical description of Ectodus descampsi, and is illustrated in the six species depicted in his figure 4. Liem did not, however, use the feature as a major apomorphy for the OA as a whole. Indeed, he used the presence of an extensive fossa in Asprotilapia as an autapomorphic character for that genus (Liem, 1981 : 208). In all <9A species the fossa is clearly defined, and is limited anteriorly by a prominent, near-vertically aligned ridge on the anguloarticular. The principal surface for muscle insertion is situated on the lateral aspect of the bone, and is thus unlike the generalized condition where it lies on and across the bone's posterior margin. The insertion face, and hence the area of the fossa, varies in size amongst members of the OA. It is largest in Asprotilapia, smallest in Cunningtonia, with the other species occupying various inter- mediate positions in the range. Parenthetically, it may be noted that amongst the species I would now include in the 6>A, the fossa is small in Cyathopharynx, of intermediate size in Xenotilapia and Grammatotria, and largest in Callochromis. Amongst the outgroup taxa examined, an 0A type fossa is found only in Lethrinops (Lake Malawi), Trematocara (Lake Tanganyika), Chromidotilapia batesi and C. kingsleyae (West Africa) and, in a poorly developed state, in the following Lake Malawi 'Haplochromis' species 'H. ' prostoma, 'H. ' johnstoni, 'H. ' breviceps and 'H. ' tetrastigma. (For the use of the name 'Haplochromis' see Greenwood [ 1 979 : 3 1 7]). In all other outgroup taxa examined the adductor mandibulae A2 inserts along the some- what medially expanded posterior margin of the anguloarticular. There is no obvious evidence to suggest a recent common ancestry shared by the O\ and the Chromidotilapia species, nor one between any of the Lake Malawi 'Haplochromis' and either the OA or the Chromidotilapia species. 262 P. H. GREENWOOD In the current state of our knowledge one can be less certain about making a similar state- ment with respect to the OA and either Trematocara (also from Lake Tanganyika) or the Malawian genus Lethrinops. Thus a suspended judgement only can be given on whether the presence of an OA-type fossa in these three taxa is a homoplasy, or whether it is a synapomorphy for a group of higher universality than the one under discussion (see also p. 257). Because the fossa is present in all OA species (including the new additions, see below) and because it is congruent with other apomorphic features shared by them, it can, I would con- sider, be taken as further evidence for the monophyly of the lineage. To summarise this review of group characters in the Ophthalmotilapia assemblage (as defined by Liem, 1981), the congruent apomorphic features are: (i) The presence of a palatopterygoid gap (see p. 254) (ii) The morphology of the palatine bone (see p. 257) (iii) The presence of an auricular process on the opercular bone (see p. 259) (iv) The shape of the lachrymal bone (1st infraorbital); see p. 259) (v) The presence of a well-defined, laterally placed fossa for the insertion of the A2 adductor mandibulae muscle on the anguloarticular bone (see p. 261). The Ophthalmotilapia assemblage reconsidered On the grounds of all their constituent species sharing the five features listed above, and because none possesses any feature which might suggest other relationships, six further genera can be included in the Ophthalmotilapia assemblage (see Figs 1,3, 10 and 1 1). The new additions are: (i) Xenotilapia Blgr, 1899 (type species X. sima Blgr) (ii) Callochromis Regan, 1920 (type species Pelmatochromis macrops Blgr) (iii) Grammatotria Blgr, 1899 (type species G. lemairii Blgr) (iv) Cyathopharynx Regan, 1920 (type species Tilapia grandoculis Blgr; but see p. 284). (v) Cardiopharynx Poll, 1942 (type species C. schoutedeni Poll) (vi) Aulonocranus Regan, 1920 (type species Paratilapia dewindti Blgr) Although not apparently relevant to the question of their phyletic relationships, it may be noted that these six genera also share with members of Liem's original OA all the other features discussed in the previous section (i.e. characters 2, 3, 5 & 6). For taxonomic and biological details of these genera and their contained species, reference should be made to Poll (1946 & 1956). Since I can find no grounds for maintaining Cyathopharynx and Cardiopharynx as separate genera (see p. 282), all further references to these taxa will be made under the name of the senior synonym, Cyathopharynx. Liem (198 1 : 208) has already suggested that Xenotilapia, Callochromis and Aulonocranus might be the sister lineage of the Ophthalmotilapia assemblage, but he felt that more information was needed before their 'precise relationships' to the others could be determined. His reason for making this suggestion was that all three genera share with the OA a palatopterygoid gap and various derived features of the hyomandibula, ie characters (1) and (2) above. That the three taxa also shared the other six and supposedly apomorphic features originally used to define the OA, was not noted by him. Although I would be chary of claiming that the 'precise relationships' of Xenotilapia, Callochromis, Aulonocranus, Grammatotria and Cyathopharynx have been determined, I would submit that an a priori case can be established for including them within the Ophthalmotilapia assemblage itself, and not just as a sister-group to that lineage. Before going on to consider intralineage relationships within the expanded OA, some comments must be made about certain features in Aulonocranus and Xenotilapia. In Aulonocranus the lachrymal has the characteristic shape of that bone in other OA species (Fig. 3H), but it lacks the anteroventral peak; the anteroventral angle is rounded and THE OPHTHALMOT1LAPIA ASSEMBLAGE OF CICHLID FISHES 263 so resembles the condition found in most cichlid taxa. It is possible that this atypical anterior profile might be attributed to the greatly inflated laterosensory canals in the lachrymal of Aulonocranus. In most Xenotilapia species too, the lachrymal is atypical for the OA because in these species there are, modally, five and not six openings to the laterosensory canal system (Figs 3C & D). There is, however, considerable inter- and intraspecific variation in pore number; some species have six pores, others only four, and some individuals have a different number of pores on each side of the head. Clearly, pore number is an unstable characteristic in Xenotilapia. The genus also differs from all other OA taxa, and all other African cichlids I have examined, in having the posterior opening to the lachrymal laterosensory system positioned below and not opposite the anterior canal opening in the second infraorbital bone. As in Aulonocranus, the outline shape of the lachrymal in Xenotilapia is a typical OA one (Figs 3C & D); not surprisingly, considering the number of species (11), there is rather more variation on that basic shape in Xenotilapia than in other members of the assemblage. Relationships within the Ophthalmotilapia assemblage In its original form, the assemblage was divided into two major sublineages, one comprising only Asprotilapia leptura, the other containing the four remaining genera, Ectodus, Lestradea, Ophthalmotilapia and Cunningtonia (see Liem, 198 1 : 208 & fig. 9). As defining features for the larger sublineage, Liem employed two supposedly synapomorphic characters: (i) the morphology of the lachrymal, and (ii), the dominance of the A, division of the adductor mandibulae muscle complex (Liem's characters 15 & 16 respectively). The Asprotilapia lineage was recognized both by the absence of those features, and, more importantly, by its having six presumed autapomorphic characters (see Liem, 198 1 : 208). As argued above (character (8)[15], page 259), the features of the lachrymal must now be considered an apomorphic character for the whole OA (including the new additions and Asprotilapia itself)- The muscle character, according to Liem, has two components. First, that the A, division of the adductor mandibulae has become the dominant component of the complex, its cross sectional area surpassing '. . . that of the other parts', and second, that '. . . its origin has expanded ventrally at the expense of the adductor mandibulae part A2' (Liem, 1981: 208). It is difficult to test the first claim adequately, and my attempts to do so failed to confirm Liem's claims, especially if, as his statement implies, the A, division is dominant to both the A2 and A3 divisions combined. However, the area of origin of A, in the taxon concerned is very clearly greater than that of A2 when measured by its extent along the vertical arm of the preoperculum (see fig. 6 in Liem, 1981). When, however, the additional OA taxa are taken into account, the second feature shows a continuous range of variation from a state where the origins of both A, and A2 occupy an approximately equal depth on the vertical preopercular limb, to one where the origin of A2 is virtually excluded from that limb and thereby is almost confined to the horizontal part of the bone. Furthermore, even within a single genus (as in Xenotilapia and Callochromis} some species have A, and A2 with almost equal depths of vertical origin (the plesiomorph condition in cichlids), others have the depth of A, greater than A2, and yet others have A2 with a much greater vertical depth of origin than A, (Fig. 5B). Thus there would no longer seem to be any grounds for maintaining the unity of the Ectodus- Cunningtonia sublineage on the basis of its myological characters. The peculiar arrangement of the adductor mandibulae muscles in Asprotilapia still stands as a well-defined autapomorphy for the genus. Here, division A, is markedly reduced, both in the depth of its origin on the preoperculum, and in its overall bulk (Fig. 5A), a condition not found elsewhere in the OA. Other features, however, suggest that Asprotilapia is closely related to some of the newly incorporated members of the assemblage (p. 265). 264 P. H. GREENWOOD B Fig. 5 Superficial adductor mandibulae muscles (left side) of: A, Asprotilapia leptura; B, Xenotilapia sima. AM, & AM2 : adductor mandibulae divisions 1 and 2; TAM, : tendon of insertion for AM,. Although a primary dichotomy within the OA cannot be made on the characters employed by Liem, such a dichotomy can be established on differences in the length of the gut and the manner in which it is arranged within the visceral cavity (see Figs 6 & 7). Liem (1981 : 209; character [19]) used intestinal length to define a group of taxa (Ophthalmotilapia, Cunningtonia and Lestraded) within the original 0A, but he did not comment on the spatial arrangement of the alimentary tract in those species. Within the expanded OA, the member taxa can be grouped into those with an intestinal length less than 3 times the standard length of the body, modally 2-3-2-5 times SL, and those with an intestinal length 3-6 times the standard length. Species in the first group have the relatively short gut coiled into a few loops whose arrangement is in an essentially anteroposterior direction. In contrast, species with a long gut have the intestine much coiled and the coils are arranged in an essentially transverse direction (see Figs 6 & 7). At first sight this transverse arrangement gives an erroneous impression of the intestine actually being coiled around the stomach (Fig. 7). A long and complexly coiled gut is a derived feature, occurring in several cichlid lineages. But, since these lineages are not closely related it can be treated as a synapomorphy at the level of universality involved here. THE OPHTHALMOTILAPIA ASSEMBLAGE OF CICHLID FISHES 265 » mm Fig. 6 Alimentary tract (left lateral view) of an Asprotilapia subassemblage taxon (Grammatotria lemairei). »mm Fig. 7 Alimentary tract (left lateral view) of an Ophthalmotilapia subassemblage taxon (Ophthalmotilapia boops). Taxa of the OA belonging to the group with a long and transversely coiled intestine are: Lestradea, Ophthalmotilapia, Cunningtonia and Cyathopharynx - hereafter referred to as the Ophthalmotilapia subassemblage; their interrelationships will be considered later (see p. 271). The group with a short and longitudinally coiled intestine comprises the genera Asprotilapia, Callochromis, Xenotilapia, Grammatotria, Ectodus and Aulonocara- hereafter referred to as the Asprotilapia subassemblage. Four genera in the Asprotilapia subassemblage, viz. Asprotilapia, Callochromis, Xenotilapia and Grammatotria, share an apomorphic feature which suggests their shared common ancestry. This character is the presence of a fully developed pharyngeal hanging pad, with its associated modifications to the superficial anatomy of the gill-rakers; see Figs 8 &9. The pad is an hypertrophied and well-circumscribed, forwardly directed, and turgid fold of the buccopharyngeal tissues. It lies immediately anterior to the upper pharyngeal bones and extends forward and downward, as a visor-like projection, for a short distance in front of the first gill-arch. Posterolaterally the pad is fused with the thickened tissue covering the epibranchial gill-rakers of the first gill-arch, but over most of its width the visor-like part is 266 P. H. GREENWOOD Fig. 8 Pharyngeal hanging pad in Xenotilapia boulengeri. Left side, seen from a slightly dorsolateral viewpoint. mm Fig. 9 Ventral portions of the gill-arches, and the lower pharyngeal bone of Xenotilapia boulengeri, viewed from above to show the nature of the gill-rakers. separated from the buccal roof by a distinct transverse groove. This groove is open anteriorly and laterally. In the buccal midline the left and right halves of the visor-like portion are confluent with the buccopharyngeal roof. When the mouth is closed, and the ventral gill-arch skeleton is adducted, the visor occludes the pharynx, leaving only a narrow channel coincident with the medial area of confluence between the two halves of the visor and the buccopharyngeal epithelium. THE OPHTHALMOTILAPIA ASSEMBLAGE OF CICHLID FISHES 267 The pharyngeal surface of the visor is thrown into a large number of broad-based but terminally acute papillae. When the gill-arches are adducted the papillose area is brought into close contact with the upper surface of the cerato- and hypobranchial regions of the gill-arches. These, in turn, are covered by a greatly thickened and soft epithelium. The inner and outer gill-rakers on the ceratobranchial of each arch are joined transversely by anvil- shaped folds of thickened tissue so that, superficially, there appears to be but a single series of rakers, with each raker extending across the breadth of the arch (Fig. 9). A pharyngeal hanging pad is known from two other, and very dissimilar, African genera, Chromidotilapia and Tylochromis, and in the South American Geophagus (see Trewavas, 1 974 : 389-392). Since there are several features strongly indicating that none of these taxa is closely interrelated, and that none is closely related to the Ophthalmotilapia assemblage, the repeated occurrence of a hanging pad can only be interpreted as the result of convergent evolution. Any other explanation would be most unparsimonious. It would be equally unparsimonious to assume that its occurrence in four of the OA taxa was the result of independent evolution in each genus. This is particularly so since three of the four genera share another apomorphy, a high number of caudal vertebrae in Xenotilapia, Asprotilapia and Grammatotria, and a second derived character, the shape of the dentary, is shared by Xenotilapia, Callochromis and Grammatotria, of which taxa Callochromis alone does not share the vertebral apomorphy. Thus, on the basis of their all possessing a pharyngeal hanging pad, Xenotilapia, Callochromis, Grammatotria and Asprotilapia1 are taken to form a natural group within the <9A. The group can be further subdivided on the distribution within its members of certain other derived features. Xenotilapia, Callochromis and Grammatotria all have a peculiarly shaped dentary (Fig. 10). When viewed laterally, the dorsal margin of the bone is seen to dip downwards immediately behind the last tooth in the outer row. It continues posteriorly at this lower level until it curves upwards to form the anterior margin of the coronoid process. The alveolar surface is confined to that part of the bone preceding the step, behind which it is edentulous. The dentary of Asprotilapia will be discussed below. This type of dentary, as far as I am aware, is not found in any other cichlid from Lake Tanganyika, or for that matter from Lake Victoria either. It is, however, closely approached by the dentary in the Malawian genus Lethrinops and in some 'Haplochromis' species from that lake. The significance of this similarity, and the occurrence in Lethrinops of a palatopterygoid gap, is discussed on page 279. Within the group comprising Xenotilapia, Callochromis and Grammatotria it is impossible to determine which two genera are the more closely related since no clear-cut linking synapomorphies can be recognized. It is accepted that the diagnostic 'generic' characters for each genus are autapomorphies for that taxon. At present the trio can only be treated as an unresolved trichotomy, but with the suggestion that further research may show Xenotilapia and Grammatotria to be sister taxa. Asprotilapia, the fourth member of the group, is a most distinctive taxon, in which Liem (1981 : 208) identified six autapomorphies. These must now be reviewed in the context of the expanded Ophthalmotilapia assemblage. As in earlier discussions, Liem's apomorphy number is given in square brackets. (i) [9]. The elongate, slender mandible has an expanded adductor fossa for the A2 division of the adductor mandibulae muscle. As noted earlier (p. 261) the adductor fossa is expanded in several members of the OA, particularly in species of the group to which Asprotilapia belongs. However, even amongst those species the fossa is most expansive in Asprotilapia. 'Microbranchiospines are present in all four of these Tanganyika genera; in this respect they resemble Tylochromis and differ from Chromidotilapia (see discussion in Trewavas, 1 973 : 1 7 & 1 974 : 388). 268 P. H. GREENWOOD ADDF Fig. 10 Dentary and anguloarticular in two species of the Asprotilapia subassemblage : A, Grammatotria lemairei (lateral view); B & C, Xenotilapia boulengeri (lateral and ventral views respectively). ADDF : adductor fossa. NF : nerve foramen. 1mm Fig. 11 Left dentary and anguloarticular of Asprotilapia leptura in : A, lateral view; B, occlusal view. In B the teeth have been restored (based on a spirit specimen), but in A only the tooth scars are shown. THE OPHTHALMOTILAP1A ASSEMBLAGE OF CICHLID FISHES 269 The mandible is not, in my view, especially elongate, particularly when it is compared with that element in other members of the Asprotilapia subassemblage (cf. Figs 10 & 1 1). Its gross morphology differs from that in Xenotilapia, Callochromis and Grammatotria since it lacks a 'stepped' alveolar margin, and because each ramus of the jaw has a more abrupt and stronger medial curvature towards the symphysis. Also, in Asprotilapia, immediately before the dentary curves inwards, the alveolar surface is produced laterally so as to form a noticeable, shelf-like overhang of the underlying ramus (Fig. 1 1). Overall, the dentary in Asprotilapia bears a fairly close resemblance to that bone in Labeotropheus of Lake Malawi, a resemblance enhanced by the tricuspid, slender-necked, procumbent and movably implanted teeth present in both genera. Asprotilapia has, how- ever, a shallower dentary, and the anguloarticular is taller and more expansive than in Labeotropheus. Parenthetically it may be noted that Asprotilapia, like Labeotropheus, has an enlarged and similarly shaped cartilaginous meniscus underlying the premaxillary ascending process, and a similar fleshy medial projection overlying the broad palato- premaxillary ligaments. Observations made from radiographs of the two species, and from manipulation of preserved specimens, indicate that the protrusile mechanisms in the two species are very similar. There are, however, no reasons to doubt that these similarities should be treated as homoplasies. (ii) [10]. The posterior head of the transversus dorsalis anterior muscle is absent. This seems to be a clear-cut autapomorphy, but should be checked in more examples than the single specimen available to Liem and myself. (iii) [11]. Lateral ethmoids greatly enlarged. This again is an apparently good autapomorphy. (iv) [12]. Interorbital width greatly reduced. The interorbital width is reduced in some Xenotilapia species, but in none is it as narrow as in Asprotilapia. (v) [13]. The reduced articular process of the premaxilla is in a more forward position. There is considerable and continuous variation in the relative position of this process in Xenotilapia species, and indeed within the taxa of the entire OA. It would not, therefore, seem to be a character of particular value. (vi) [14]. The greatly enlarged cranial condyle and the premaxillary process constitute the bulk of the maxilla. The maxilla of Asprotilapia is less outstanding when compared with that bone in other members of the subassemblage, especially Xenotilapia (Fig. 12). In X. boulengeri, for example, the process is larger than in Asprotilapia. The cranial condyle, however, is largest in Asprotilapia and, as compared with all other <9A species, the whole bone is relatively foreshortened. In the context of the expanded <9A, I would consider that at least three of the autapomorphies originally proposed (i.e. nos. i, ii and iii above) retain their validity (if, that is, the apomorphic features of the lower jaw are interpreted as has been done here). Although not listed as an autapomorphy by Liem (198 1), the peculiar condition of the A, division of the adductor mandibulae muscle in Asprotilapia would seem deserving of that status. In Asprotilapia, as compared with all other OA taxa, A, is a very short and narrow muscle with an extremely long tendon of insertion (Liem, 1981; fig. 6; also Fig. 5), and an area of origin much smaller in all respects than that of the A2 division. No other species in the OA has this arrangement of the adductor mandibulae muscles. 270 P. H. GREENWOOD mm 1mm Fig. 12 Right maxilla, in lateral view, of: A, Xenotilapia boulengeri; B, Asprotilapia leptura (the damaged ventral margin of the premaxillary saddle is indicated by a broken line). When commenting on the unusual A, muscle in Asprotilapia, Liem (1981:203) makes particular reference to a tendon stemming from the muscle's principal tendon of insertion, and which joins the tendinous part of adductor division A^. This emphasis might give an impression that the vertically directed interconnecting tendon is a unique (or unusual) feature of Asprotilapia. That is not so because the tendon is present in all cichlids whose jaw musculature has been examined (see for example Liem & Osse, 1975: fig. 6; Stiassny, 1981 : 80, and figs 8 & 1 1 [tA.b]; also personal observations on species other than those studied by these authors). Asprotilapia is, however, unusual in having a discrete, ligament-like condensation in the connective tissue between the premaxilla and dentary, inserting on the lateral (and not the medial) face of the premaxilla. Interestingly, despite the resemblances in lower jaw morphology between Asprotilapia and Labeotropheus (see above p. 269), the pattern of adductor muscles in the two genera is quite different. Labeotropheus has the typical generalized cichlid arrangement. The various autapomorphies of Asprotilapia serve to indicate the taxon's isolation within its group. For the moment it can only be treated as the sister taxon to the other three genera (i.e. Callochromis, Xenotilapia and Grammatotria) combined. The two remaining taxa in the Asprotilapia subassemblage (see p. 265), Ectodus and Aulonocranus, are 'interrelated' only at the level of their sharing with their supposed sister- group, Asprotilapia, Callochromis, Xenotilapia and Grammatotria, the plesiomorphic feature of a short intestine. With one possible exception, neither Ectodus nor Aulonocranus has any uniquely shared derived features suggestive of their recent common ancestry. The exceptional feature concerns the marked elongation of the first, and to a lesser extent the second pelvic fin rays in adult males. In Aulonocranus the first ray extends to about the middle of the anal fin, and in Ectodus to a point beyond its spinous part, but never as far as the middle of the fin. Other members of the Asprotilapia subassemblage have variously modified relative proportions of different pelvic fin rays (see Poll, 1956) but none has the first ray elongated to the degree found in Ectodus and Aulonocranus. The significance of this feature is, however, somewhat questionable (see p. 272). THE OPHTHALMOTILAPIA ASSEMBLAGE OF CICHLID FISHES 271 In Liem's scheme (1981 : 208-9, fig. 9), Ectodus was allied with Lestradea, Ophthalmo- tilapia and Cunningtonia (now considered to be a separate sublineage, see below) and not with Asprotilapia. Liem's grounds for this alliance were based on Ectodus sharing two apomorphic characters with Lestradea, Ophthalmotilapia and Cunningtonia, namely a distinct antroventral process on the lachrymal bone, and a dominant Aj division in the adductor mandibulae muscle complex. As was argued above (pp. 262-263) the former character is one shared by all members of the OA (except Aulonocranus) and the latter is a variable feature of little value as an indicator of relationships within the OA. Aulonocranus was not included in the original OA, although Liem (1981 : 206 & 208) did suggest that it might be related to that assemblage. The genus is readily identified by one outstanding apomorphy, the hypertrophy of its cephalic laterosensory canal system, and as a probable correlate, the enlarged saccular bulla in the basioccipital and prootic bones. Ectodus has one autapomorphy, viz. the vertical and horizontal limbs of the pre- operculum are of equal or almost equal length (see Liem, 1981 : 209). Liem also ranked the enlarged saccular bulla as an autapomorphy, but the bulla is enlarged to an equal extent in Lestradea and Ophthalmotilapia amongst members of the original OA, and in Aulonocranus and Cyathopharynx among the new additions to the assemblage. Indeed, apart from Callochromis, Xenotilapia and Grammatotria the saccular bulla is noticeably enlarged in all OA species, the degree of enlargement showing a continuous increase from the condition in Asprotilapia through to that in Aulonocranus, with Lestradea, Ectodus and Ophthalmo- tilapia all close to Aulonocranus. Turning now to the second lineage of the primary dichotomy, the Ophthalmotilapia subassemblage (p. 265), one again finds difficulty in establishing intragroup relationships, but little difficulty in recognizing autapomorphies for the constituent genera, viz. Lestradea, Ophthalmotilapia, Cunningtonia and Cyathopharynx. Since Lestradea lacks the various derived features shown by its congeners in the subassemblage it would appear to be the plesiomorph sister taxon to the other three genera combined. Liem (1981 : 209) singled out two autapomorphies for Lestradea (i) the edentulous anterior process of the lower pharyngeal bone is only half as long as the toothed part (his apomorphy 20), and (ii), the body of the maxilla is stout, and has a prominent postmaxillary process (his apomorphy 2 1 ). I cannot agree with Liem's statement about the relative proportions of the anterior process of the lower pharyngeal bone* The Lestradea specimens I have examined all have this process as long as, or almost as long as the toothed part, a condition approaching that in Ophthalmotilapia and Cunningtonia. This condition must be considered derived relative to that in Astatotilapia and many other African cichlids. In these various taxa the edentulous anterior process of the bone is indeed half or less than half as long as the toothed part. The body of the maxilla in Lestradea is stout and the posterior process is prominent, but in both features the bone does not differ from the maxilla in Ophthalmotilapia where the process is a little less prominent. A relatively short maxilla with a prominent posterior process is, it would seem, a common feature in the whole Ophthalmotilapia assemblage. Cyathopharynx is readily distinguished by its autapomorphous lower pharyngeal bone (Fig. 23), with its deeply concave occlusal surface, heart-shaped dentigerous area, and greatly inflated body below that surface. There are, however, no synapomorphies (except group ones) shared by Cyathopharynx and any other member of the subassemblage. Liem (1981:209) recognized three synapomorphies which suggested to him that Ophthalmotilapia and Cunningtonia were members of a monophyletic unit. The presumed synapomorphies were (i) jaw teeth with long stalks, and movably implanted, (ii) the first pelvic ray greatly elongate (Liem's apomorphies 22 & 23 respectively), and (iii) the posterior margin of the vertical preopercular limb is straight and forms a 90° angle with the horizontal limb. 272 P. H. GREENWOOD The teeth in all members of the OA (sensu lato) are movably implanted, and in all species the teeth could be described as having 'long stalks', albeit with specifically distinct but varying degrees of slenderness. For example, in both these features the outer jaw teeth in Ophthalmotilapia are very like those in Lestradea, but those in Cunningtonia have a much more slender and elongate neck than do the teeth in any other OA species. The first and second pelvic rays are elongate (much more so in males than in females) in both Ophthalmotilapia and Cunningtonia, with, in the former, the first ray somewhat longer than the second. But, when other species in the expanded OA are taken into account one finds that the condition of the two rays in Cyathopharynx furcifer is like that in Cunningtonia longiventralis, and that Aulonocranus also has elongate rays but which extend only to the middle of the anal fin base and not to the posterior margin, or slightly beyond, as they do in Cunningtonia and Cyathopharynx furcifer. Cyathopharynx schoutedeni has elongate first and second pelvic rays too, but in this species it is the second ray which is the longer and, unlike the elongate first ray in C. furcifer, it extends posteriorly only a short distance beyond the spinous part of the anal fin. Thus it is difficult to treat marked elongation of the first, or first and second pelvic rays as a synapomorphy for Ophthalmotilapia and Cunningtonia. That it is a character showing continuous variation and one that is incongruent with other apomorphies would also preclude its use as an indicator of recent shared common ancestry for the genera exhibiting it, namely Aulonocranus, Ophthalmotilapia, Cunningtonia and Cardiopharynx (see below). Some comment on the spatulate, bifid tips to the first ray in males of Ophthalmotilapia species would be appropriate here. The feature appears to be a unique apomorphy for Ophthalmotilapia, indeed it is one of the reasons given by Liem (1981 :210) for synonymizing Ophthalmochromis with that genus. Spatulate tips have not been mentioned in the formal descriptions of any other species, nor have I seen such modifications in any of the taxa, other than Ophthalmotilapia, which I have examined. However, Brichard (1978 : 187) describes the pelvic fin in Cyathopharynx furcifer as having '. . . a long filament tipped with a yellow double spatula'. On page 190 of the same book he comments on 'The ventral filaments, reaching the end of the anal fin are each tipped with a double yellow-orange spatula'. Finally, Brichard (1978 : 148 & 149) provides two illustrations of a live individual (or individuals) showing what certainly looks like a spatulate tip to the protracted pelvic fin rays. Brichard is an experienced underwater-naturalist and one is hesitant to suggest he has misidentified his material. On the other hand, in his description (Brichard, 1978 : 326) of Ophthalmotilapia ventralis (as Ophthalmochromis ventralis) he remarks that The males . . . have very long pelvic filaments also forked like O. nasutus, but the tips are without spatulae (although they are pale yellow like those of O. nasutusY; bold type added. Clearly there is some terminological confusion here since none of the male O. ventralis specimens I have examined, or those which have been described elsewhere, lacks well-defined spatulae. The tips of the elongate pelvic rays in Cyathopharynx are brightly coloured, and seem to serve the same ethological function as the spatulae in Ophthalmotilapia. Perhaps the confusion stems from that colour similarity rather than a structural one? Until spatulate Cyanopharynx are described formally, the uncertainty will remain. In itself, very marked elongation of the first and second pelvic rays is a derived feature (see below), but in the context of the OA it is not clear at what level of universality it can be recognized as a synapomorphy. For example, if used to unite Aulonocranus, Cyathopharynx, Ophthalmotilapia and Cunningtonia, pelvic fin length would be incongruent with the group synapomorphy of an elongate and complexly folded intestine shared by all except Aulonocranus, which has a short and simply folded intestine. If, on the other hand, because of its short gut Aulonocranus was taken to be the plesiomorph sister taxon of the others, then where would Lestradea which has a long gut but short pelvic fins be placed? The problem is further compounded by Ectodus which has a short and simply folded gut but elongate first and second pelvic rays produced to a degree almost comparabale with those in Aulonocranus. THE OPHTHALMOT1LAPIA ASSEMBLAGE OF CICHLID FISHES 273 In no case are there any known synapomorphies which are uniquely congruent with protracted pelvic fin length, and which would thereby establish a strong case for arguing that the gut character is a homoplasy. Finally, it must be recalled that some relative elongation of the first and second pelvic rays is of relatively common occurrence in African cichlids (see Greenwood, 1981), and that the degree of elongation must be treated as a continuous variable, albeit one rarely reaching the extremes found in Cunningtonia and Ophthalmo- tilapia. Liem's third synapomorphy (involving the shape of the preoperculum; see page 271) is also difficult to substantiate, particularly in the context of the expanded OA. In all constituent species of the O\ sensu law the vertical and horizontal limbs of the preopercular bone meet at, or very nearly at, a right angle, and in all except Ophthalmotilapia and Cunningtonia the posterior margin of the vertical limb curves inwards for a short distance near its dorsal extremity. Because Ophthalmotilapia and Cunningtonia have the bony flange behind the vertically aligned laterosensory canal tube narrowing imperceptibly, rather than abruptly, the entire posterior margin of the preoperculum does give the impression of being straight in these two species. The difference between the two types of posterior margin is, however, very slight and is almost obliterated by the condition in Cyathopharynx. Here the dorsal extremity of the margin is slightly indented, but less noticeably so than in most other OA taxa. Thus, of the three apomorphies under review, only the nature of the preopercular margin, a not particularly trenchant character, would seem to be a synapomorphy linking Ophthalmotilapia and Cunningtonia. On the morphological evidence alone, it is thus impossible to hypothesize precise intragroup relationships for the Ophthalmotilapia subassemblage, except to note that on a simple summation of derived features Lestradea would seem to be the most plesiomorph taxon. At the generic level the other taxa are readily identified by their particular autapomorphies (see below). It is possible that these currently obscure and therefore uncertain intralineage relation- ships will be clarified when more data are available on the breeding habits of its constituent species. Brichard (1978 : 108), for example, groups Cyathopharynx with Ophthalmotilapia as polygamous spawners in which there is no contact between the sexes at the nest site. The import of Brichard's statement is not really clear, and the phyletic importance of most ethological characters still awaits evaluation. Nevertheless it is suggestive that Brichard did single out these taxa as forming a distinctive reproductive class. Returning now to the autapomorphic features of the genera constituting the sub- assemblage, one finds that Ophthalmotilapia (sensu Liem, 1981 : 210) is distinguished by the bifid spatulae in which each elongate first pelvic ray terminates, and the subdivision of the retractor dorsalis muscle of the upper gill-arches into two distinct heads (see Liem, 1981 :201,fig.8D). Cunningtonia has as its principal autapomorphies the nature of its oral dentition, the stout foreshortened dentary (Fig. 1 3) and the stout premaxilla. 5mm Fig. 13 Left dentary and anguloarticular of Cunningtonia longiventralis in lateral view. 274 P. H. GREENWOOD Most of the jaw teeth are very slender and tall, with strongly recurved, tricuspid and broad crowns. The teeth are arranged in wide bands over the entire alveolar surface of the premaxilla and on the transverse part of the dentary, but on the lateral alveolar surface the teeth are much stouter and are unicuspid. The palatine of Cunningtonia is also unique in having its facet for articulation with the lateral ethmoid expanded medially into a shelf-like projection. When viewed from the side, especially in specimens prepared as alizarin transparencies, the shelf has a spine-like appearance (see Liem, 198 1 : 2 10; apomorphy 26). Liem considered that the symplectic in Cunningtonia was '. . . very elongate' (his apomorphy 28), but I find that it is of virtually equal relative length in all members of the OA. In Cyathopharynx the principal autapomorphy is the peculiar, heart-shaped and deeply concave dentigerous surface of the lower pharyngeal bone and, of course, the correlated changes in the shape of the upper pharyngeal elements (see p. 288). The nature of the apophysis for the upper pharyngeal bones in the Ophthalmotilapia assemblage Like Liem (1981), I have not taken into account the nature of the pharyngeal apophysis when analysing intragroup relationships amongst members of the OA (see Greenwood, 1978, for an evaluation of this character in determining phyletic relationships; also Fryer & lies, 1972:504^5^.). Based on material examined personally, the distribution of apophyseal types (defined as in Greenwood, 1978) within the two major subassemblages of the 0A is as follows: Asprotilapia subassemblage Ophthalmotilapia subassemblage Hap.1 Troph. Tilapia Hap. Troph. Tilapia Callochromis Xenotilapia — — Cyatho- Lestradea (a few spp.) pharynx Xenotilapia Aulono- (most spp.) cranus Ophthalmotilapia Grammatotria* Ectodus Cunningtonia lffap. = Haplochromis type; Troph. = Tropheus type; Tilapia = Tilapia type. *In all specimens the apophysis is of the Haplochromis type on one side, and the Tropheus type on the other. It is interesting that no true Tilapia type apophysis occurs amongst members of the Asprotilapia subassemblage, but that three of the four taxa in the Ophthalmotilapia subassemblage do have an apophysis of that type. In contrast, a Haplochromis type apophysis occurs in three members of the Asprotilapia subassemblage but not in any taxa of the Ophthalmotilapia subassemblage. It must be borne in mind, however, that the Tropheus apophyseal type is structurally intermediate between the Haplochromis and Tilapia types (see Greenwood, 1978) and that in the Asprotilapia subassemblage certain taxa have more than one type of apophysis. Indeed, the three specimens of Grammatotria lemairei examined have a Haplochromis type apophysis on one side of the skull and a Tropheus type on the other. It is also interesting to note that if the Tropheus category (of Greenwood, 1978), which Regan did not recognize, is ignored and the taxa in that category are returned to the one in which they were placed by Regan (1920), then the entire Asprotilapia subassemblage is of the Haplochromis type, and the Ophthalmotilapia subassemblage becomes exclusively of the Tilapia type. THE OPHTHALMOTILAPIA ASSEMBLAGE OF CICHLID FISHES 275 Such a pattern might well be taken to argue against my earlier criticisms of the pharyngeal apophysis as an indicator of phyletic relationships at a high level of universality (Greenwood, 1978) and that, on the contrary, African cichlids can be divided into 'Tilapicf and 'Haplochromis"1 supralineages as suggested by Regan (1920). If the latter argument is accepted, then the synapomorphies delimiting the Ophthalmo- tilapia assemblage as a whole must be considered as homoplasies developed independently in the two subassemblages recognised here. That assumption would produce a scheme of relationships less parsimonious than the one proposed above and earlier by Liem (1981). Also, the existence of intermediate conditions (i.e. the Tropheus type) in the structure of the apophysis, and of other cases where a classification based on apophyseal structure is incongruent with different and apparently synapomorphic characters (see Greenwood, 1978; Liem & Stewart, 1976) would seem to support the rejection of apophyseal structure as an indicator of phyletic relationships at the level proposed by Regan. A review of other schemes of relationship suggested for members of the Ophthalmotilapia assemblage Regan (1920 : 52) did not present detailed arguments for his views on the interrelationships of the Lake Tanganyika genera, which were strongly influenced by his assumption of there being a fundamental dichotomy of African cichlids into those with a 'TilapicC type apophysis, and those with a 'Haplochromis'' type (see above). As a result of this basic difference in approach, it is difficult to make direct comparisons between Regan's ideas and those put forward in this paper. However, some comments can be made on certain of Regan's suggested relationships involving OA members and taxa outside that assemblage. For example, Ophthalmotilapia was grouped with Cyathopharynx, Cunningtonia, Asprotilapia, Petrochromis and the Malawian genus Petrotilapia (then considered a species of Petrochromis); furthermore, Regan suggested that Ophthalmotilapia was closely related to Limnotilapia (now synonymised with Simochromis, see Greenwood, 1979) and that it had '. . . given rise to Cyathopharynx'. Petrochromis and Petrotilapia were included in this grouping because, in their dental morphology and pattern, they are strikingly similar to Cunningtonia (see p. 280 below). No reasons were given for including Asprotilapia, a taxon quite unlike the others in its gross morphology and in its dentition; presumably the reason lay in Regan's (1920 : 42) belief that the 'Skeleton (is) essentially similar to that of Ophthalmotilapia ventralis . . .'. The skeletal features noted by Regan (1920 : 41 & 42) were, it should be emphasised, not those used in this paper; most can be treated as plesiomorph characters when used at the level of analysis involved here. Presumably it was the same suite of skeletal characters which led Regan to suggest a close relationship between Limnotilapia (i.e. Simochromis) and Ophthalmotilapia, a relationship which I cannot accept since ''Limnotilapia'' apparently shares no derived features with any members of the OA.. Ectodus (as a putative ancestral morphotype) was grouped by Regan (1920: 53) with Callochromis, Xenotilapia and Grammatotria,\hQ taxa being given that order of increasing morphological derivation. Again no detailed reasons are given for this grouping, save that all its taxa have a 'Haplochromis'' type pharyngeal apophysis and small conical teeth. In effect, however, it approximates closely to the arrangement proposed in this paper. Regan (1920 : 53) also included, albeit implicitly rather than explicitly, Aulonocranus and Trematocara with those genera listed in the previous paragraph. The association of Aulonocranus with Trematocara was, presumably, based on both genera having hyper- trophied cephalic laterosensory canal systems (Regan, 1920:47); no other relationship with Aulonocranus was suggested, save that it is 'Intermediate between Haplochromis and Trematocara.'' The linking of Aulonocranus and Trematocara with the Ectodus- Grammatotria group (see above) was apparently based on the common possession of small conical teeth and a 'Haplochromis' type of pharyngeal apophysis. 276 P. H. GREENWOOD That Regan did not consider there to be any relationship between his Asprotilapia- Ophthalmotilapia and his Ectodus-Grammatotria ( + Aulonocranus) groups is doubtless due to his basic assumption that the endemic genera of Lake Tanganyika were derived from '. . .two ancestral types, one nearly related to Limnotilapia and the other to Haplochromis' (Regan, 1920:53). After Regan's initial analysis of the Tanganyika cichlids, no further attempt to interrelate the endemic genera of the lake was made for more than fifty years. In 1972 Fryer & lies paid considerable attention to this problem, in particular to the assumption that there was a basic diphyletic origin of the flock. However, despite their professed uncertainty about the value of the pharyngeal apophysis as an indicator of phyletic relationships, Fryer & lies (1972 : 506, fig. 337) virtually followed Regan's (1920) scheme. They were, of course, able to include three genera described since that time, namely Lestradea, Cardiopharynx and Ophthalmo- chromis. Cardiopharynx is now considered a synonym of Cyathopharynx (see p. 282) and Ophthalmochromis was synonymised with Ophthalmotilapia by Liem (1981: 210-21 1). As would be expected, Fryer & lies considered Ophthalmochromis and Cardiopharynx to be the sister taxa of Ophthalmotilapia and Cardiopharynx respectively. Interestingly, they associated Lestradea with Asprotilapia, Cunningtonia and the Ophthalmotilapia- Ophthalmochromis pair, but gave no reasons for doing so. Their tentative alliance of Cyathopharynx -{-Cardiopharynx with Lobochilotes and Limnotilapia is not explained either, and only partly follows Regan who implied some relationship between Limnotilapia and Lobochilotes, but also included Gephyrochromis, Simochromis and Tropheus in the same group -again without a detailed explanation (Regan 1920:52). I can find no synapomorphic characters to support the idea of a close relationship between Lobochilotes and any member of the Ophthalmotilapia assemblage. Like Regan, Fryer & lies (1972 : fig. 337) treat Aulonocranus and Trematocara as close relatives, but give the two genera an origin separate from that of the taxa currently grouped in the 0A. Leptochromis (now renamed Reganochromis, see Whitley, 1928), a genus not mentioned in Regan's analysis, is included by Fryer & lies as a member of their Ectodus, Callochromis, Xenotilapia lineage, but again no reasons are given. This suggested relationship is discussed on p. 278 below. In effect, the main difference between the schemes proposed by Regan (1920) and Fryer & lies (1972) lies in the latter authors not portraying any taxa in an ancestor-descendent relationship, as was implied, or stated explicitly, in Regan's treatment. Also, Fryer & lies indicate a more distant relationship than did Regan between Limnotilapia (i.e. Simochromis) and other members of the latter author's Ophthalmotilapia group (see above, p. 275). In their final analysis Fryer & lies are less definite in their suggested relationships than was Regan (see figure 337 in Fryer & lies, 1972 : 507); their phylogram was to be '. . . regarded as extremely tentative'. Liem's (1981) wide ranging review of the 0A is, in its treatment of anatomical and morphological detail, far more thorough than either of the other two reviews. It was also the first to employ a basically cladistic (sensu Hennig, 1966, phylogenetic sensu Wiley, 1981) methodology. Liem brought together certain taxa from Regan's two major groups (see above p. 275), namely Ectodus with some elements of Regan's Ophthalmotilapia- Asprotilapia group, but excluded other taxa from his Ectodus-Grammatotria assemblage (see p. 275 above). The present analysis (also cladistically based) finally brings together, in a single lineage, all but one pair of taxa from Regan's two groups, the exceptions being Petrochromis and the Malawian genus Petrotilapia (see above, p. 275). It also includes Aulonocranus (but not Trematocara) from a third group which Regan implied had some relationship with his Callochromis-Grammatotria lineage (Regan, 1920 : 53). Effectively it hypothesizes that the two major Regan groups are sister lineages within a larger taxon which, following Liem (1981), can be named, informally, the Ophthalmotilapia assemblage (see Fig. 1 4). Asprotilapia SA ..Ophthalmotilapia SA. (U 1-5 Fig. 14 Cladogram for the Ophthalmotilapia assemblage based on the 10 apomorphic characters discussed in this paper. Page numbers, given in brackets after each numbered character, refer to those pages on which the character is discussed in detail. An interrogation mark precedes character 9 since its apomorphic status is doubtful (see p. 272). ( 1 ) Palatopterygoid gap (p. 254) (2) Auricular process on the operculum (P. 259) (3) Morphological features of the palatine bone (p. 257) (4) Outline shape of the lachrymal (1st infra- orbital bone), and the presence of six laterosensory canal pores (p. 259) (5) Adductor fossa on the lateral aspect of the anguloarticularbone (p. 261) (6) Intestine long and transversely coiled p. 264) (7) Presence of a pharyngeal hanging pad and associated modifications to the gill-raker morphology (p. 265) (8) Dentary with a distinct 'step' (p. 267) (9) First branched pelvic fin ray produced (P. 272) (10) Dorsal part of the flange behind the vertical part of the preopercular laterosensory canal not narrowing abruptly (p. 273) 278 P. H. GREENWOOD Summary of the taxonomic conclusions and a discussion of the sister-group problem in these and other lake cichlids The Ophthalmotilapia assemblage, originally comprising the genera Ectodus, Lestradea, Asprotilapia, Cunningtonia and Ophthalmotilapia (Liem, 1981) can now be expanded to include Xenotilapia, Callochromis, Grammatotria, Aulonocranus and Cyathopharynx (with which is synonymized Cardiopharynx). Taxonomically, the assemblage is recognized as a monophyletic lineage on the grounds of its member species sharing a unique congruence of five apomorphic characters (pages 254-262; Fig. 14). Two major sublineages can be recognized within the assemblage. One, characterized by having a short and simple coiled intestine, comprises the genera Ectodus, Aulonocranus, Asprotilapia, Xenochromis, Callochromis and Grammatotria. It can be further subdivided on the basis of various synapomorphies shared by four of its members (see pages 263-274 and Fig. 14). The other major sublineage contains Lestradea, Ophthalmotilapia, Cunningtonia and Cyathopharynx, species in which the intestine is long and complexly coiled (see pages 264-265). Attempts to subdivide this lineage have not proved satisfactory, but it would seem that Lestradea is the plesiomorph sister-group of the other three genera (pages 271-274 and Fig. 14); possibly amongst these three genera Ophthalmotilapia and Cunningtonia are sister taxa, but the entire group is, for the moment, probably best treated as an unresolved polychotomy. No sister-group, or even a single taxon, has so far been satisfactorily identified amongst the cichlids of Lake Tanganyika. Regan's (1920 : 52) suggestion of close relationship between Limnotilapia (i.e. Simochromis, see Greenwood, 1979) and Ophthalmotilapia (and hence Cyathopharynx, Asprotilapia and Cunningtonia as well) cannot be corroborated on the basis of shared synapomorphies. When comparisons are made with other Tanganyika taxa the results are equally unproductive except that two OA group synapomorphies occur, singly, in some species of ' Limnochromis* and Trematocara. For example, in Trematocara marginata, but in no other species, there is a poorly differentiated OA-like projection from the anteroventral angle of the lachrymal (see p. 259). A similar projection occurs in 'Limnochromis'' permaxillaris and 'L.' pfefferi, both of which are now placed in Poll's genus Gnathochromis. Both the ' 'Limnochromis* species and Trematocara marginata have only 5 pores in the lachrymal, but other 'Limnochromis' species which lack the projection, V otostigma, L. auritus and L. abeeli, have 5 or 6 pores. Neither Trematocara nor ' ' Limnochromis'' has the characteristically shaped lachrymal of the OA species, and the distribution pattern of the two OA group-features indicates an independent (i.e. homoplastic) origin in the two genera. Regan's (1920:53) suggested relationship between Aulonocranus and Trematocara apparently stems from the hypertrophied laterosensory canals, and pores, present in both taxa. Apart from that feature, and the weak OA-type lachrymal peak in one species of Trematocara, there are no derived features uniquely shared by the two genera. Admittedly there is a trend amongst the OA species for there to be some degree of hypertrophy in the laterosensory canal system of the lachrymal. But, in the absence of other synapomorphies it would be unrealistic to use a trend character as a basis for suggesting group relationships, especially when that trend occurs in several other lineages as well. In this particular instance, too, the lowest degree of canal enlargement is found in those OA species with the least number of derived features (i.e. Ectodus and Lestradea), and which are therefore taken to be the plesiomorph members of their respective subassemblages. The tentative phylogenetic schemes proposed by Fryer & lies (1972 : 507, fig. 337) are not always arranged so as to suggest sister-group relationships with taxa outside the OA. They do, however, show Leptochromis (i.e. Reganochromis) as a sister taxon of Ectodus, Callochromis, Xenotilapia and Grammatotria, and Aulonocranus is paired with THE OPHTHALMOT1LAPIA ASSEMBLAGE OF CICHLID FISHES 279 Trematocara. Once again, there are no shared derived features to substantiate such relation- ships, and none which might indicate that either Reganochromis or Trematocara is the sister-group, or part of the sister-group, to the Ophthalmotilapia assemblage. The only taxon which consistently shows more than a single OA group synapomorphy amongst a number of its species is the Malawian genus Lethrinops. I have examined alizarin preparations and dry skeletons of five Lethrinops species, the type species Lethrinops lethrinus, and L. praeorbitalis, L. parvidens, L. auritus and L. longimanus. In all there is a distinct palatopterygoid gap and a well-defined, although not extensive OA type adductor fossa on the anguloarticular bone (Figs 1 5 & 16). The palatopterygoid gap is relatively smaller than in most OA species, but in none of the Lethrinops species examined is there any contact between the palatine and the entopterygoid. Unlike members of the OA, the Lethrinops species have a much deeper entopterygoid, and one that either rests along the upper margin of the quadrate or slightly overlaps that bone medially. In OA species, most of the entopterygoid lies medial to the quadrate, and is thus largely obscured by it in lateral view. As a consequence of this spatial relationship the dorsal margin of the entopterygoid in Lethrinops lies at a level nearer the palatine head than it does in OA species. * mm Fig. 15 Left suspensorium of Lethrinops lethrinus. The shape of the palatine (Fig. 15) in Lethrinops differs somewhat from that in the OA taxa(see p. 257 above). Its posterior margin is slightly concave, and the angle between this margin and the head of the bone is less nearly rectangular; the posterodorsal margin contributing to the angle is also less acute in Lethrinops; indeed, in some specimens and species it is almost rounded. But, as in the OA species the body of the bone is expanded posteriorly so that the bone's proportions are nearer those of the OA type than that commonly found amongst African cichlids. The occurrence of this particular palatine shape in association with a palatopterygoid gap raises the question of whether or not the two characters are correlated. That a similarly shaped palatine does occur in at least two species without a palatopterygoid gap (viz. Limnochromis abeeli [Lake Tanganyika] and Astatotilapia macropsoides [Lakes Edward and George]), would seem to argue against correlation, but the possibility requires further testing. The adductor fossa in Lethrinops (Fig. 16) is well defined but, as compared with the fossa in members of the Asprotilapia subassemblage amongst the OA (p. 261) it is less extensive. It is, however, comparable with the fossa in members of the Ophthalmotilapia subassemblage (p. 265). 280 P. H. GREENWOOD omm Fig. 16 Left dentary and anguloarticular ofLethrinops lethrinus, lateral view. An adductor fossa of this type is not restricted to members of the OA, but also occurs in several seemingly unrelated taxa, including some 'Haplochromis* species from Malawi (see p. 261). Thus, in itself, the fossa cannot be considered a unique apomorphy; its value as a group synapomorphy stems solely from its congruence with other apomorphic characters. There is a third derived character found in the five Lethrinops species which is also present in one subgroup of the OA, namely a stepped dorsal margin to the dentary, with the teeth confined to the higher level of the step (Fig. 16). Amongst the OA taxa this feature is found only in Xenotilapia, Callochromis and Grammatotria (all members of the Asprotilapia subassemblage; see p. 267). Its restricted distribution within the OA considerably reduces its potential significance as a character indicative of a possible relationship between Lethrinops and the OA. That it apparently occurs only in these OA species and in Lethrinops, and that both groups have a palatopterygoid gap is, nevertheless, intriguing and requires further investigation. Attempts to evaluate the two apomorphic features shared by Lethrinops and the OA in its entirety (i.e. the palatopterygoid gap and the adductor fossa) are hampered by lack of comparative data from the Malawi cichlids as a whole. A relatively superficial survey shows, however, that the adductor fossa is present only in some haplochromine species (see p. 26 1 ). Whether or not these haplochromines are closely related to Lethrinops has not been adequately tested, but preliminary investigations do not suggest that this is the case. The situation regarding the palatopterygoid gap is different. I have examined specimens of all the described genera of Malawi fishes, but by no means all their included species. In none is there a palatopterygoid gap. Thus, the character appears restricted to Lethrinops and the OA (see also p. 255). In summary, it seems that no group of Lake Tanganyika cichlids consistently shows one or more of the group synapomorphies for the OA. On the other hand, in Lake Malawi at least some species of Lethrinops share two derived features with all members of the OA, and only one of these features (the adductor fossa) occurs in other Malawi taxa. The Lethrinops species also have a third derived feature, the shape of the dentary, which is present in one lineage amongst the OA. As it stands, this indication of a possible sister-group relationship between the OA and Lethrinops is no more than suggestive. It could well be refuted as an example of convergence when more is known about the interrelationships of the cichlids from Lake Malawi and those of Lake Tanganyika. There are several cases of close similarity existing between certain features in endemic taxa of each lake, but few between species in those lakes and endemic taxa from Lake Victoria. As examples one may mention that the dentition in Cunningtonia is virtually identical with that in Petrotilapia and there are marked similarities in the jaw anatomy of the two genera (Petrochromis from Lake Tanganyika can also be included in this example); or, the morphology of the dentary in Asprotilapia which is like that of Labeotropheus a Malawian genus also sharing several features with Tropheus from Lake Tanganyika. Finally, one can cite the many similarities in syncranial architecture existing between Simochromis of Tanganyika and the Pseudotropheus species complex of Lake Malawi. THE OPHTHALMOTILAPIA ASSEMBLAGE OF CICHLID FISHES 281 These are by no means the only cases that can be, or have been, cited of supposed convergence or parallelism between the cichlid faunas of the two lakes (see Fryer & lies, 1 972). Adequate explanations for these similarities are, however, far more difficult to find. An example of similarity involving much greater geographical separation than that between Tanganyika and Malawi, and one which incorporates a greater number of species as well as a mosaic distribution of similar characters amongst the species, involves two members of the OA, another, unrelated, genus from Lake Tanganyika, a Malawian taxon and Neopharynx schwetzi, a monotypic genus from the lower Fwa (Kasai drainage in south- western Zaire; for a full description of N. schwetzi, see Poll, 1948). >mm Fig. 17 Lower pharyngeal bone of Neopharynx schwetzi, occlusal view (from a specimen in paratypical series, MRAC 7 1 29 1-7 1 299). Neopharynx schwetzi has a lower pharyngeal bone morphologically and dentally almost identical with that of Cyathopharynx (see Figs 17 & 24). Its oral dentition, in contrast, is virtually identical with that in Petrochromis (Tanganyika) and Petrotilapia (Malawi), and is quite unlike that in Cyathopharynx. As far as the morphology of the teeth is concerned, but not their distribution on the dentary, Neopharynx also closely resembles Cunningtonia of Lake Tanganyika. It differs from all three taxa in the shape of its premaxilla, but the morphology of the premaxillary teeth is, as might be expected, very similar in all four genera. The relationships of Neopharynx have yet to be established; probably they lie with two other Fwa endemics, Cyclopharynx and Callopharynx, genera having an extreme development of the Neopharynx-Cyathopharynx type of lower pharyngeal bone (for details see Poll, 1948). Neopharynx has neither an OA type lachrymal, a palatopterygoid gap, nor an OA-type of adductor fossa, and the shape of its palatine bone is close to the generalized form. Thus the similarities between Neopharynx, Cyathopharynx and Cunningtonia are undoubtedly homoplastic, as most probably are the similarities shared with Petrochromis and Petrotilapia. The Neopharynx example underlines the problems involved in attempting to work out interrelationships amongst cichlid fishes, as do the repeated appearances of certain derived features shown by members of the Ophthalmotilapia assemblage in species which appear to be but distantly related to the OA. Surmises about the interrelationships of African lake cichlids have, I believe, been unduly influenced, perhaps even inhibited, by three major factors. Firstly, the idea that there are two 282 P. H. GREENWOOD basic lineages, a ' Tilapia" line and a 'Haplochromis' one (see discussion in Greenwood, 1 978; also p. 274 above). Secondly, that the major lakes are, faunistically, closed basins and have been so almost since their inception, with the result that the cichlids of a lake are presumed to have evolved from one or a few ancestral species originally trapped there (see discussion in Fryer & lies, 1972; and Greenwood, 1974). In other words, assumed histories for the lakes have been given too great a weight in deciding whether a feature was the result of convergence, parallelism, or the consequence of common ancestry. The third, and overriding, factor is a paucity of specific and critical studies on the phylogeny of the fishes. Overall resemblances, or the use of characters without adequate outgroup comparisons, are often major weaknesses influencing decisions on relationships. The effect of these three factors has resulted in a tendency to restrict the search for sister- groups to a single lake and to the appropriate 'Tilapia' or 'Haplochromis' lineage. Admittedly, at lower levels of universality sister species are generally to be found within the same lake or proto-lake system (Greenwood, 1980); the problems arise when attempting to establish relationships at somewhat higher taxonomic levels. The Ophthalmotilapia assemblage, and the search for its sister-group are good examples of problems encountered at these two levels. The existence of endemic species flocks, the superficially close similarity of species in different flocks, and indeed of many different taxa outside the lakes, all help to complicate the issue. Under such circumstances the possibility and probability of homoplasy are theoretically enhanced, as in practice are the problems associated with their resolution. What is needed to resolve these problems are tests of the assumption that a so-called species flock is really of monophyletic origin. If a lake's cichlid fauna was derived from a few species which are not true sister species, and if the true sister taxa were the ancestors of another flock, then the situation suggested by the apparent relationship of Lethrinops (Malawi) and the 0A (Tanganyika) could well be a real one. The idea first put forward by Regan (1922) that the Malawi 'flock' carries indicators of its monophyly must be seriously questioned (Greenwood, in press). No indicators of monophyly have been suggested for the Tanganyika 'flock' (even at the levels of the supposed 'Tilapia' and "Haplochromis" type basic stocks). The possibility of a close relationship between the faunas of the two lakes deserves very careful examination. The status of Cyathopharynx Regan, 1920 and Cardiopharynx Poll, 1942 In his original description of the monotypic genus Cardiopharynx, Poll (1942 : 346) noted the great similarity between its peculiarly shaped lower pharyngeal bone and the lower pharyngeal of Cyathopharynx. He differentiated the two genera because Cardiopharynx has, as compared with Cyathopharynx: (i) Larger scales (36-38 c/48-64 in a longitudinal series (see Poll, 1956:1 27). (ii) Jaw teeth in two rows, the teeth, in both jaws, of equal size (c/3-5 rows; teeth in the outer row larger than those of the inner rows), (iii) Dentigerous surface of the lower pharyngeal bone cardiform (cf rounded in Cyathopharynx) (iv) Supraoccipital extending forward to a level above the anterior margin of the orbit (c/to the mid-orbital region only) (v) Parietal crests ending above the centre of the orbit (c/extending to a point above the posterior part of the orbit) (vi) More vertebrae (36, i.e. 17+19) c/32-34 (i.e. 1 6 or 1 7 + 1 6 or 1 7) Poll gives no reasons why these characters should be used to separate the taxa at a generic level, and neither does he indicate why the great similarity in pharyngeal morphology, and its uniqueness, should be outweighed as an indicator of close phyletic relationship by the diagnostic characters he enumerates. THE OPHTHALMOTILAPIA ASSEMBLAGE OF CICHLID FISHES 283 None of these latter features can be considered uniquely apomorphic for Cardiopharynx, and now that more material is available several are found to be less trenchant than was first thought to be the case, as the following comments show. The teeth in both jaws of all Cardiopharynx specimens I examined are invariably arranged in two rows, but in Cyathopharynx there is a greater variation than was intimated by Poll (1942 & 1956). In the majority of specimens examined, the inner premaxillary row is, in places, irregularly arranged so as to give the appearance of a double row wherever the irregularities occur. Occasionally there are specimens in which the inner tooth row is clearly and regularly double, thus giving a total count of three tooth rows; also occasionally it is distinctly single, giving a total of two rows. In none of the specimens is there a total of more than three premaxillary rows. The inner row of teeth in the dentary is generally single; in a few fishes, however, it is somewhat irregular and so comes to resemble the modal condition in the premaxilla. Contrary to Poll (1946), I can find no marked difference between the taxa in the relative size of inner and outer teeth. In both genera the outer teeth, in both jaws, are clearly taller and stouter than those of the inner row or rows, and not of equal size in Cardiopharynx as claimed by Poll. The most that can be said is that in Cardiopharynx the size difference between outer and inner row teeth is a little less marked than in Cyathopharynx. In a later redescription of both taxa, Poll (1956) commented on the outer teeth of Cardiopharynx being more or less tricuspid in young fishes, but he gave no size-range over which tricuspid teeth are found. In specimens 60-105 mm SL I have examined, there are no outer tricuspids, whereas in specimens of Cyathopharynx of a comparable size range and up to 1 12 mm SL, distinctly, and also weakly, tricuspid teeth do occur. In larger Cyathopharynx specimens the teeth are exclusively and clearly unicuspid. The difference in the shape of the dentigerous surface of the lower pharyngeal bone (iii above, p. 282) is due entirely to a marked median depression in the posterior face of the bone and of the toothed area in Cardiopharynx. In Cyathopharynx this margin of the bone is slightly and more broadly indented, and there is no indentation of the posterior tooth row (Fig. 23). In all other respects the lower pharyngeal bone in both taxa is identical. As noted above (p. 27 1 ) it represents a uniquely derived condition amongst the cichlids of Lake Tanganyika. The shape of the pharyngeal teeth, tall and slender, with spatulate crowns that are not broader than the neck, and their cardiform pattern on the alveolar surface of the bone, is the same in both genera (Fig. 24). Likewise, the morphology of the principal upper pharyngeal bones is identical, as is the morphology and pattern of their teeth. Unlike the lower teeth, those on the upper pharyngeal bones do have a slight, shoulder-like cusp at the base of the spatulate crown surface. The anterior point reached by the supraoccipital and parietal crests (iv & v above) is variable intragenerically. In the skulls I have examined there are specimens from each genus showing conditions intermediate between those originally used as diagnostic features for the two genera. Finally, there are the supposedly intergeneric differences in vertebral number (vi above). I have examined 15 specimens of Cardiopharynx schoutedeni (13 from radiographs, 2 as alizarin preparations), and 12 of Cyathopharynx furcifer (10 from radiographs and 2 dry skeletons), and obtained the following counts: Cardiopharynx: Total number (excluding the fused Ui-PUi centra) 33 (f5) and 34 (flO), comprising 1 5 (fl), 16 (f7) or 17 (f7) abdominal and 16 (fl), 17(f9) or 18 (f5) caudal elements. Cyathopharynx: Total number (excluding the fused Ui-PUi centra) 32 (f5) 33 (f6) or 34 (fl ), comprising 1 6 (f9) or 1 7 (D) abdominal and 1 6 (f7) or 1 7 (f5) caudal elements. The differences in range are not very marked and there is a complete overlap in other counts, but with a slight difference in the modal number for total [34 c/33] and abdominal counts [1 7 cf\ 6] for Cardiopharynx and Cyathopharynx respectively. Thus, of Poll's (1942) original diagnostic features, only the difference in scale size remains. 284 P. H. GREENWOOD There are, however, other differences which were noted in the original diagnosis. Cyathopharynx has proportionately longer pelvic fins, in males the tip of this fin reaches the last anal fin ray or even to as far as the caudal fin fork; in Cardiopharynx it reaches only to about the middle of the anal fin. Also, in Cyathopharynx the first pelvic ray is clearly the longest whereas in Cardiopharynx either the first and second rays are equally protracted or the second ray may be the longest. Other differences involve neurocranial shape (Figs 18 & 19). Cardiopharynx has a shallower skull than does Cyathopharynx, the prootic portion of its otic bulla is more inflated, and the interorbital region is much narrower. Undoubtedly the two taxa are distinguishable. The problem is to decide at what taxonomic level their separation should be recognized. To recognize two genera on the basis of the differences discussed above is to obscure the fact that, amongst the Lake Tanganyika cichlids, Cyathopharynx and Cardiopharynx share a unique apomorphy (the form of the lower pharyngeal bone) which would indicate a common ancestry not shared with any other taxon. That relationship is, I believe, best indicated by treating the two species as members of a single genus, Cyathopharynx Regan, 1920. Cyathopharynx Regan, 1 920 Cyathopharynx Regan, 1920. Ann. Mag. nat. Hist. (9), 5: 42-43. Cardiopharynx Poll, 1942. Revue Zool. Bot. afr., 36: 346-347. TYPE SPECIES. Tilapia grandoculis Boulenger, 1899. Trans, zool. Soc. Lond. 15: 94, pi. XIX, fig. 6. Poll (1946 : 283^) has synonymized this species with C.furcifer (Blgr), 1 898. DIAGNOSIS. A member of the Ophthalmotilapia assemblage, distinguished from other members of that group by having a cardiform dentigerous surface to the lower pharyngeal bone, the body of which is inflated and nearly cardiform in outline. Cyathopharynx is distinguished from other species with a cardiform alveolar surface to the lower pharyngeal bone by, among other features, its <9A group characters (see p. 262) and by the marked elongation of the first, or first and second pelvic fin rays in adult male fishes; these protracted rays extend to at least the middle of the anal fin, and in one species, some- times as far as the fork of the caudal fin. Description Neurocranium (Figs 1 8 & 1 9). In its general outline, the skull differs little from that of the generalized haplochromine type in which the preorbital profile is slightly decurved. The orbit, however, is relatively larger than in a generalized skull, and the otico-occipital region is shorter, a correlate, probably, of the enlarged orbit since the ethmoid region retains the same proportions as in a generalized skull. The ventral apophysis for the upper pharyngeal bones is of a weak 'Tropheus1 type, in which the basioccipital barely contributes to the articular surface (see Greenwood, 1978; also p. 274 above). Suspensorium (Figs 1 C & D). As in other members of the Ophthalmotilapia assemblage, there is a distinct palatopterygoid gap (see p. 255), and the entopterygoid is shallow, with only one-third to one-quarter of its depth visible above the quadrate margin. The hyomadibula has a narrow flange anterior and dorsal to the symplectic process. The shape and proportions of the symplectic are typically those of an OA species (see p. 256). Infraorbital series (Figs 3 A & F). The lachrymal bone (1st infraorbital) has the typical outline shape, and the anteroventral process, of an OA taxon (see p. 259). There are six pores opening from the laterosensory canal system, the tubular part of which is somewhat THE OPHTHALMOTILAPIA ASSEMBLAGE OF CICHLID FISHES 285 5mm Fig. 18 Neurocranium of Cyathopharynx furcifer in : A, left lateral view; B, dorsal view. inflated. The pores, however, do not show a corresponding enlargement (i.e. they do not deviate noticeably from the generalized condition). The other infraorbital bones are little more than tubular ossifications around the sensory canal, but do have low dorsal and ventral keels. Myology. Division I of the adductor mandibulae complex has an extensive origin along the vertical limb of the preoperculum, but division II has its preopercular origin mainly from the horizontal limb of that bone; only a small area extends onto the vertical limb. The dorsal gill-arch muscles compare closely, in most respects, with those of other 0A species (see Liem, 1981 : 196-7 & 205, & fig. 8; also p. 258 above). The retractor dorsalis muscles are especially well developed with, in some individuals of both species, indications of a subdivison into dorsal and ventral components. Dentition (Fig. 20). Some aspects of the oral dentition have been commented upon already (p. 283 above). The outer row teeth in both jaws are tall and slender. In C. furcifer the crown is slightly broader than the neck and shaft of the tooth, whereas in C. schoutedeni the crown is no wider than the shaft. The crowns are slightly recurved in both species. Premaxillary outer row teeth are aligned vertically to the alveolar surface, but in the dentary the teeth situated anteriorly and anterolaterally are procumbent. The posterior dentary teeth are vertical, those of C. furcifer continuing for some distance up the coronoid process. Inner row teeth in both jaws, and both species, are noticeably smaller than those of the outer row, and are implanted so as to lie almost horizontally. Mouth. The lips are thin, and the gape is horizontal. 286 P. H. GREENWOOD 5mm Fig. 19 Neurocranium of Cyathopharynx schoutedeni in : A, left lateral view; B, dorsal view. mm Fig. 20 Outer row jaw teeth (drawn in situ) from : A & B, Cyathopharynx schoutedeni, specimen 103 mm SL (premaxillae and dentary respectively); C & D, C. furcifer, specimen 1 13 mm SL (premaxilla and dentary, respectively). Dentary teeth viewed from below. Jaws. The dentary in both species is a moderately slender bone, shallower and less robust in C. schoutedeni than in C. furcifer (Fig. 2 1 ). Anteriorly and anterolaterally the dorsal aspect of the bone is expanded into a broad surface which extends outwards to overhang, as a narrow shelf, the body of the bone. The tooth rows occupy only the outermost part of the surface, with the result that there is a wide expanse of bone lying medial to them. The laterosensory canal system and its openings in C. furcifer are more cavernous than those in C. schoutedeni. The anguloarticular has a well-defined but short fossa for the adductor mandibulae muscle, with the ridge delimiting its anterior margin particularly deep and prominent. The premaxilla (Fig. 22) has no especially outstanding features. THE OPHTHALMOTILAPIA ASSEMBLAGE OF CICHLID FISHES 287 Fig. 21 Dentary and anguloarticular, in left lateral and occlusal views respectively, of : A & B, Cyathopharynxfurcifen C & D, C. schoutedeni. 5mm Fig. 22 A & B, premaxilla ofCyathopharynxfurcifer, anterior and lateral view; C, maxilla (left) seen from a slightly ventrolateral viewpoint. 288 P. H. GREENWOOD As compared with the generalized type of maxilla, that in Cyathopharynx is foreshortened and has a well-developed, long-based posterior process (see also p. 269). The pharyngeal bones. The shape and other peculiar features of the lower pharyngeal bone (Fig. 23) are described on page 283. The upper pharyngeal bones differ less markedly from the usual condition seen in African cichlids. The outline of the alveolar surface of the major element (pharyngobranchial 3) is noticeably ovoid, but otherwise differs little from the generalised condition. Their principal difference lies in the relatively greater alveolar surface area, and its more elongate proportions. Other differences are found in the less prominent facets for articulation with the 3rd and 4th epibranchials, and in the lower summit facet (nomenclature following Barel et al, 1976: 214, fig. 26). The lower pharyngeal teeth (Fig. 24) are slender, near cylindrical in cross-section and are closely packed. Those at the periphery of the dentigerous area are weakly curved, the others i mm Fig. 23 Lower pharyngeal bone, in occlusal view of: A, Cyathopharynx furcifer, B, C. schoutedeni, and, in ventral view, C, of C. furcifer. B I \ 0.25mm Fig. 24 Cyathopharynx furcifer, pharyngeal teeth (lateral and semiocclusal views) from : A, the posterior; and B, anterior dental fields. THE OPHTHALMOTILAPIA ASSEMBLAGE OF CICHLID FISHES 289 erect. There is a noticeable and rapid increase in the height of the teeth forming the posterior 5 or 6 rows, with the teeth of the posterior row tallest and stoutest. The elongate crown of each tooth is flat, and slopes gently upwards and backwards. There is no indication of a low shoulder-like projection or cusp at the base of the crown. The shape and dense arrangement of the upper pharyngeal teeth are very similar to those of the lower bone, the teeth differing only in having a small shoulder or cusp at the base of the posteriorly directed crown. Vertebrae. Regan (1920 : 43), in his original description of Cyathopharynx, noted that the third vertebra lacks an inferior apophysis, from which the retractor dorsalis muscles originate. In four of the five dry skeletons and alizarin preparations I examined, a low apophysis is present on the fourth centrum in one fish and on the fifth centrum in three others, but none is present in the fifth specimen. Vertebral counts for the two species are given on page 283. Squamation. Scales on the body are weakly ctenoid except for the cycloid scales on the chest and belly. Those covering the thoracic region are small, and are fairly abruptly demarcated from the larger scales on the ventral flanks and the belly. The two Cyathopharynx species differ, disjunctly, in the size of their body scales, with C. schoutedeni having 36-38 scales in a longitudinal series, and C. furcifer 48-64. The species also differ, slightly, in the posterior extension of the upper lateral line pore scales, those in C. furcifer usually extending almost to the caudal fin base, whereas in C. schoutedeni the pore scales terminate at a level 3 or 4 scale rows anterior to the caudal base. There is, however, some interspecific overlap in this feature. Fins. Little can be added to the description (p. 272) of the protracted first or first and second pelvic fin rays in adult males. In females and juvenile males these rays are also noticeably longer than the others, but usually do not extend beyond the level of the anus; exceptionally they may reach the spinous part of that fin. The caudal fin is forked; adult males have the two upper- and lowermost principal branched rays produced into fine filaments. Rows of small, barely overlapping scales are present on the fin membrane (except between the three middle rays), and extend to the level of the fork. Gut. The intestine is long (ca 3 to 4 times SL) and complexly coiled in a predominantly transverse direction (see p. 264). Contained species Cyathopharynx furcifer (Blgr) 1898 Cyathopharynx schoutedeni (Poll) 1 942 Both are lacustrine species endemic to Lake Tanganyika; for detailed descriptions, figures and biological data see Poll (1956: 1 30-1 37 & 1 25-1 30 for the species respectively). Acknowledgements Gordon Howes has once again devoted much time and patience to producing the figures, and for that I am especially grateful. I also owe him a great deal of gratitude for his help with all the numerous, and monotonous, tasks he has undertaken in helping with the production of this paper. I am greatly indebted to Dr Thys van den Audenaerde of the Koninklijk Museum voor Midden-Afrika, Tervuren, who so graciously allowed me to borrow the types and other material of the river Fwa cichlids. Finally, it is a great pleasure to thank my colleague Professor Karel Liem of the MCZ whose original paper on the <9A has proved both a stimulus and a focal point for my studies on the interrelationships of the cichlid species flocks from the African lakes. 290 P. H. GREENWOOD References Barel, C. D. N., Witte, F. & van Oijen, M. J. P. 1976. The shape of the skeletal elements in the head of a generalized Haplochromis species: H. elegans Trewavas 1933 (Pisces, Cichlidae). Neth. J. Zool. 26 (2): 163-265. Boulenger, G. A. 1898. Report on the collection of fishes made by Mr J. E. S. Moore in Lake Tanganyika during his expedition, 1895-96. Trans, zool. Soc. Lond. 15 (1) : 1-30. Brichard, P. 1978. Fishes of Lake Tanganyika. T.F.H. Publications Inc., New Jersey & London. Fryer, G. & lies, T. D, 1972. The cichlid fishes of the Great Lakes of Africa. Their biology and evolution. Oliver & Boyd. Edinburgh. Greenwood, P. H. 1965. Environmental effects on the pharyngeal mill of a cichlid fish, Astatoreochromis alluaudi and their taxonomic implications. Proc. Linn. Soc. Lond. 176: 1-10. 1974. Cichlid fishes of Lake Victoria, East Africa: the biology and evolution of a species flock. Bull. Br. Mus. nat. Hist. (Zool.) Suppl. 6: 1-134. 1978. A review of the pharyngeal apophysis and its significance in the classification of African cichlid fishes. Bull. Br. Mus. nat. Hist. (Zool.) 33: 297-323. 1979. Towards a phyletic classification of the 'genus' Haplochromis (Pisces, Cichlidae) and related taxa. Part I. Bull. Br. Mus. nat. Hist. (Zool.) 35 : 265-322. 1980. Towards a phyletic classification of the 'genus' Haplochromis (Pisces, Cichlidae) and related taxa. Part II: the species from Lakes Victoria, Nabugabo, Edward, George and Kivu. Bull. Br. Mus. nat. Hist. (Zool.) 39 : 1-101. 1981. The haplochromine fishes of the East African Lakes. Kraus-Thomson Organization GmbH. Munich & London. Hennig, W. 1966. Phylogenetic systematics. University of Illinois Press, Urbana. Liem, K. F. 1973. Evolutionary strategies and morphological innovations: cichlid pharyngeal jaws. Syst. Zool. 22 (4): 42 5-441. 1981. A phyletic study of the Lake Tanganyika cichlid genera Asprotilapia, Ectodus, Lestradea, Cunningtonia, Ophthalmochromis, and Ophthalmotilapia. Bull. Mus. comp. Zool. Harv. 149(3): 191-214. & Osse, J. W. M. 1975. Biological versatility, evolution and food resource exploitation in African cichlid fishes. Am. Zool. 15 (2) : 427-454. & Stewart, D. J. 1976. Evolution of the scale-eating cichlid fishes of Lake Tanganyika: a generic revision with a description of a new species. Bull. Mus. comp. Zool. Harv. 147 (7) : 3 19-350. Poll, M. 1942. Cichlidae nouveaux du Lac Tanganyika appartenant aux collections du Musee du Congo. Revue Zool. Bot. afr. 36 (4) : 343-360. 1946. Revision de la faune ichthyologique du lac Tanganyika. Annls. Mus. Congo beige C. Zool.Serl,4(l): 141-364. 1948. Descriptions de Cichlidae nouveaux recueillis par le Dr. J. Schwetz dans la riviere Fwa (Congo beige). Revue Zool. Bot. afr. 41 : 91-104. 1956. Poissons Cichlidae. Result, sclent. Explor. hydrobiol. lac Tanganyika (1946-1947), 3 fasc.Sb: 1-619. 1981. Contribution a la faune ichthyologique du lac Tanganyika. Revision du genre Limnochromis Regan 1920. Description de trois genres nouveaux et d'une espece nouvelle: Cyprichromis brieni. Annals Soc. r. zool. Belg. Ill: 163-179. Regan, C. T. 1920. The classification of the fishes of the family Cichlidae-I. The Tanganyika genera. Ann. Mag. nat. Hist. (9) 5 : 33-53. 1922. The cichlid fishes of Lake Nyassa. Proc. zool. Soc. Lond. 1921 : 675-727. Stiassny, M. L. J. 1981. Phylogenetic versus convergent relationship between piscivorous cichlid fishes from Lakes Malawi and Tanganyika. Bull. Br. Mus. nat. Hist. (Zool.) 40 : 67-101. Trewavas, E. 1973. On the cichlid fishes of the genus Pelmatochromis with a proposal of a new genus for P. congicus; on the relationship between Pelmatochromis and Tilapia and the recognition of Sarotherodon as a distinct genus. Bull. Br. Mus. nat. Hist. (Zool.) 25 : 1-26. ~^==-4574. The freshwater fishes of rivers Mungo and Meme and Lakes Kotto, Mboandong and Soden, West Cameroon. Bull. Br. Mus. nat. Hist. (Zool.) 26 : 299^1 9. Whitley, G. P. 1*928. Studies in ichthyology. No. 3. Rec. Aust. Mus. 17 : 101-143. Wiley, E. O. \9jH?Phylogenetics. John Wiley & Sons. New York. Manuscript accepted for publication 9 September 1982 East African Cichlid Fishes The haplochromine fishes of the east African lakes P. H. Greenwood, British Museum (Natural History) May 1981, 840 pp, 3 plates, 350 figures Hardback Price £25.00 This volume brings together, for the first time, Dr. Greenwood's various papers (some now out of print) on the taxonomy and biology of the species of haplochromine fishes from Lake Victoria, east Africa. Also reprinted are his papers on the haplochromines from Lakes Nabugabo, George and Turkana (Rudolph), two papers dealing with the classification of the genus Haplochromis, and a recent essay on the explosive evolution of cichlid fishes in Africa. An index to the 200 species dealt with in this book (and their current generic place- ment), and a general introduction to the evolutionary and taxonomic problems posed by these biologically complex and fascinating fishes, are included. Published jointly by British Museum (Natural History) (exclusive U.K. rights) and Kraus-Thomson Organization Ltd. (all other rights). ISBN 3 601 00438 6 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 Diffiugia in Britain (Rhizopoda, Protozoa). By Colin G. 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 Humphry Greenwood Morphological studies on some Difflugiidae from Yugoslavia (Rhizopoda, Protozoa). By Colin G. Ogden & Andjelija Zivkovic Printed by Henry Ling Ltd, Dorchester Osteology, genitalia and the relationships of Acanthodactylus (Reptilia: Lacertidae) E. N. Arnold Zoology series Vol 44 No 5 26 May 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 Vol 44 No 5 pp 291-339 British Museum (Natural History) Cromwell Road London SW7 5BD Issued 26 May 1983 Osteology, genitalia and the relationships of Acanthodactylus (Reptilia: Lacertidae) • 2 6 h AY 198 E.N.Arnold t Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD Contents Synopsis 291 Introduction 292 The reality of the genus Acanthodactylus 293 Systematic position of Eremias guineensis 296 Characters varying within Acanthodactylus 297 Osteological characters 297 Hemipenial characters 300 Polarity of hemipenial features 303 Origin of hemipenial differences 304 Description of the hemipenes of different species 305 External features 307 Species boundaries and species groups 311 A. micropholis 311 The A. cantons group, A. gongrorhynchatus and A. haasi. . . . 311 A. schreiberi and A. boskianus 315 The A. grandis complex 316 The A. tristrami group 318 The /I. erythrurus group 318 The A. pardalis group 319 The A. scutellatus group 322 The A. opheodurus group 329 Inter-relationship of the species of Acanthodactylus 329 Acknowledgements 336 References 336 Addendum 338 Synopsis Acanthodactylus is reassessed, supplementing the external features previously used with new data from the skeleton and hemipenis. The genus appears to be closely related to Eremias and Mesalina rather than to Latastia as was previously thought, and 'Eremias' guineensis is confirmed as an Acanthodactylus. It is suggested that genitalia have an enhanced propensity to 'store' evidence of shared evolutionary experience in the form of common characters among descendants, when compared with other organ systems. Such characters deserve relatively high weight in assessing relationships. However, not all genital characters can be interpreted in this way for some seem likely to have evolved as physical isolating mechanisms between similar species and, in such cases, closely related forms may have radically different genitalia. Differences of this kind, together with some osteological features, have proved important in establishing the species status of several forms usually regarded as subspecies or varieties. Thus the four subspecies of A. cantoris are now accorded full species status as A. cantoris, A. blanfordii, A. schmidti and A. arabicus and a similar upgrading may well be appropriate for two taxa usually subsumed in A. tristrami: A. (/.) tristrami and A. (t.) orientalis. Within the A. pardalis complex, A. pardalis, A. maculatus and A. spinicauda are regarded as separate species and the form listed by Bull. Br. Mm. nat. Hist. (Zool.) 44(5): 29 1-339 Issued 26 May 1983 292 E. N. ARNOLD Boulenger (1921) as var. bedriagai is treated as a subspecies of A. pardalis; a similar un-named West Moroccan population is also assigned to this species. Recently available material makes it probable that A. grandis and A. fraseri are closely related and perhaps allocatable to the same highly variable species. Within the A. scutellatus group the following taxa recognized by Bons and Girot (1962) are assigned to A. scutellatus itself: A. s. scutellatus, A. s. audouini, A. s. hardyi, A. i. inornatus and A. dumerilii. A. longipes is retained as a separate species and the same status is given to A. aureus which Bons and Girot regarded as a subspecies of A. inornatus. Geographical variation requires considerable further study in a number of taxa including the A. grandis complex, A. boskianus and the A. scutellatus group but a number of currently recognized subspecies are invalid such as A. tristrami iracensis Schmidt, 1939 ( = A. (/.) orientalis), A. pardalis latastii ( = A. maculatus) and probably several of the forms in the A. scutellatus group. An attempt has been made to estimate a phylogeny for the species of Acanthodactylus, although considerable character conflict exists. Introduction The lacertid lizard genus Acanthodactylus Wiegmann, 1834 contains about 26 species. It occurs from Spain and Portugal across the Sahara desert and its periphery to the Red Sea, over most of Arabia and as far north as Cyprus and the Syrian-Turkish border; it also extends through Iraq, south and east Iran, south Afghanistan, Pakistan and northwest India. All its members are quite small, maximum body sizes of populations varying from about 52 mm to around 105 mm from snout to vent. They are diurnal and essentially ground- dwelling lizards usually found in relatively flat, often sandy situations and occurring in a wide variety of dry habitats which usually have at least some vegetation and range from open woodland to the borders of quite severe desert. Substrates occupied vary from quite hard loess and clay to aeolian sand. All species appear to be mainly active hunters and feed largely on small invertebrates including ants. Body temperatures of normally active animals are usually in the range 36° to 41° C (personal observations; Duvdevani & Borut, 1974a). Like most open-country lizards, Acanthodactylus species are probably very prone to bird predation and are also taken by other vertebrates such as snakes and monitor lizards (Varanus). Predator avoidance seems to depend largely on crypsis (colour match with substrate is often very good), fleeing, tail autotomy and the use of burrows. All species are oviparous and usual clutch size varies from two to about seven eggs, females in many populations appearing to produce more than one clutch annually. The majority of forms seem to mature within a year of hatching although some, like A. erythrurus in Spain and Portugal, may take two seasons. The most detailed synopsis of the genus to date is that of Boulenger (192 1) which although inevitably to some extent out dated, remains extremely useful, providing detailed descrip- tions of many forms. However, the amount of material available for study has increased massively over the past fifty years. In particular, specimens from many areas previously unsampled, such as much of the Sahara desert and Arabia, have been obtained. Furthermore, both Boulenger and subsequent workers have depended almost entirely on external characters. As there are reasons for believing that these on their own can be misleading when judging lacertid relationships (see for example Arnold, 1973) it seems worthwhile to increase the range of characters considered and, in the present paper, osteology and the structure of the hemipenis are taken into account. What follows is not a formal revision but an overview of Acanthodactylus is given paying especial attention to the objective reality of the genus, species boundaries and, so far as they can be judged, inter-relationships of its members. Although the results presented here differ considerably from previously held opinions, the genus still requires a more detailed appraisal based on the large but scattered collections available in continental Europe and North America. RELATIONSHIPS OF ACANTHODACTYLUS 293 In this paper, the methods of phylogeny estimation employed are those discussed by Arnold (1981 a). They depend largely but not entirely on Hennig's (1950, 1 966) precept that joint possession of a derived character state is prima Jade evidence of relationship. The word relationship is used in its genealogical sense: two species are more closely related to each other than to a third if they share a common ancestor not shared by that form. The following terms coined by Hennig are used, together with the adjectives derived from them: apomorphy — a derived character state; synapomorphy — a derived character state shared by two or more species and possibly indicating their relationship to each other; plesiomorphy — a primitive character state; symplesiomorphy — a primitive character state snared by two or more species, it does not indicate their relationship. Monophyletic and holophyletic are used in the sense of Ashlock (1974). Abbreviations used BM(NH) — British Museum (Natural History), London; CAS — California Academy of Sciences, San Francisco; CM— Carnegie Museum, Pittsburgh; EBD — Estacion Biologica de Donana, Seville); INHM — Iraq Natural History Museum, Baghdad; JUM — Jordan University Museum; MCZ — Museum of Comparative Zoology, Harvard; NMW — Naturhistorisches Museum, Vienna; RSM — Royal Scottish Museum; USNM — United States National Museum, Washington. The reality of the genus Acanthodactylus On the basis of external features, Boulenger (19 18a) described the genus Acanthodactylus as 'un des plus naturels et des plus nettement delimites de la famille des Lacertides'. Exam- ination of skeletal and hemipenial characters provides additional support for Boulenger's view and Acanthodactylus is confirmed as a clearly denned assemblage that shows no integration into other genera. Most of its features are found in the lizard usually known as Eremias guineensis but it is certain that this form should really be included in Acantho- dactylus (see p. 296). Features present in all or most species are listed below. 1 . Frontal bones completely fused in adults and at least largely so in juveniles. 2. Often a fontanelle in the anterior wall of the orbit between the frontal and prefrontal bones. 3 . A backwardly directed spur of jugal bone absent. 4. Parietal fontanelle present, 5. Parietal bone not projecting backwards over the supraoccipital. 6. Postorbital and postfrontal bones usually separate (fused only in A. cantoris). 7. Postorbital bone not filling supratemporal foramen. 8. Parietal and squamosal bones not usually in contact. 9. Pterygoid teeth present or absent (often considerable intraspecific variation). 1 0. Epipterygoid not usually in direct contact with pro-otic bone. 1 1 . Fourteen scleral ossicles present in each eye. 12. Scleral ossicle number 14 (following numbering system of Gugg, 1939) lacks a radially directed peripheral section (see Fig. 1). 13. Number of presacral vertebrae ranges from 23 to 27, in most cases 23-26. 14. In the post-thoracic series of free dorsal ribs, the longer anterior ribs are fewer than the shorter posterior ones. 1 5. Ribs on last presacral vertebra very reduced or absent. 294 E. N. ARNOLD Fig. 1 Scleral ossicles of Acanthodactylus; arrow indicates scleral ossicle 14 which lacks a radially directed peripheral section. 16. Sternum with a more or less heart-shaped fontanelle, which is sometimes divided into left and right sections. 1 7. Sternal: xiphisternal rib formula 3 : 2 or less commonly 3:1. 18. Clavicle expanded medially with a large fenestra in this region, so that the bone forms an uninterrupted loop. 19. Interclavicle cruciform, the lateral arms usually directed obliquely forwards. 20. Only the principal coracoid foramen present. 21. Caudal vertebrae of the C-type (Arnold, 1973: 305); that is, the most anterior autotomic vertebrae have two pairs of transverse processes, the members of the posterior one being longer and directed obliquely backwards. 22. Hemipenis and armature usually asymmetrical with medial side reduced (see p. 300). 23. Hemipenis with an armature consisting of a flat intramuscular plate, one or two clavulae and short connectors. 24. In species where the hemipenis and armature is not very reduced there may be more than four connectors. 25. Nostril closable by a valve hinging on the posterior side of the opening. 26. Nostril nearly always situated between a postnasal, an internasal and the first upper labial (not in A. guineensis, although the situation in this species is derivable from that found in other Acanthodactylus, see Fig. 2). 27. First upper labial broad above but sides converge downwards (not in A. guineensis', see comments about previous character). 28. Occipital scale reduced or, more usually absent. 29. A distinct collar of imbricate scales beneath neck. 30. Dorsals small and granular or larger, imbricate and keeled with rounded posterior borders. 3 1 . Maximum number of ventral scales in a row across the belly varies from 8 to 1 8. 32. Toes with three longitudinal rows of scales around them and fingers with three or four rows. 33. Subdigital lamellae keeled. 34. Lateral rows of scales on the toes and sometimes fingers forming pectinations. 35. Femoral pores present. 36. Tail more or less cylindrical, longer than body. RELATIONSHIPS OF ACANTHODACTYLUS 295 Fig. 2 Right nasal regions of Eremias and Acanthodactylus'. (a) 'Eremias' ( = Acanthodactylus) guineensis, adult: (b) Eremias nitida, adult: (c) 'Eremias'' ( = Acanthodactylus) guineensis, juvenile: (d) Acanthodactylus erythmrus lineomaculatus, juvenile: (e) A. e. lineomaculatus, atypical juvenile, BM 1966.430. Arrows indicate first upper labial scales. Of these features, the following are probably derived, rather than primitive, within the Lacertidae as a whole: 1,2,3,5,7,8, 10, 12, 15, 16, 21, 22,24, 25,27, 28, 31, 32, 33 and 34. Only number 27 appears to be unique to Acanthodactylus but 22, hemipenial asymmetry with the medial side of the organ reduced, is found elsewhere only in Philochortus Matschie, 1893 which, on other grounds, does not seem to be closely related. Monophyly is also suggested by (i) the great similarity between the species of Acanthodactylus so that they are interconnected by high levels of resemblance; (ii) possession of a unique combination of derived features even if they themselves are not unique to the genus; (iii) a coherent geo- graphical range. The relationship of Acanthodactylus to other lacertids is difficult to judge outside the 296 E. N. ARNOLD context of a comprehensive revision of the Lacertidae. Boulenger (1921) suggests that the genus is related to Latastia Bedriaga, 1884 but the two share only a couple of the derived features listed above, namely 1 and 33. Most derived features are shared with Eremias Wiegmann, 1834 (used in the restricted sense of Shcherbak, 1974, for the Palaearctic species) and Mesalina Gray, 1838 (used for the north African and southwest Asian species originally referred to Eremias— see Arnold, 19806). Eremias shares 1, 2, 3, 7, 8, 14, 15, 16, 28, 32, 33 and often 25 and 34 while Mesalina shares 1, 2?, 3, 5, 7, 8, 10, 15, 16, 21, 33 and sometimes 28. More characters need to be examined before it can be decided which of these is likely to be the sister taxon of Acanthodactylus or whether this is Eremias plus Mesalina. Systematic position of Eremias guineensis Eremias guineensis Boulenger, 1887a was described on the basis of a single hatchling, supposedly from 'Brass, Mouths of Niger' (Nigeria). In fact, as Schmidt (1919) has already suggested, this locality is almost certainly erroneous, or the result of accidental trans- portation, for all the specimens collected since have come from places far to the north of Brass in the Doka and Sudan woodland areas (vegetation classification of Rosevear, 1965) of Nigeria and Ghana (BM(NH) specimens), Niger (Pappenfuss, 1969) and Cameroon. Material from the latter country was described as a separate species, Eremias benuensis Monard, 1949 but Pappenfuss correctly synonymized this form with E. guineensis. The differences noted by Monard (p. 740) result largely from comparing adult Cameroon animals with Boulenger's description of a single juvenile, as is clearly apparent now that a number of adults are available from Nigeria and other more western localities. The ostensible differences in head and frontal scale proportions and relative head and leg lengths all result from allometric changes during growth, and the supposedly distinctive conditions of the supraocular scales, supraciliary granules and subnasal scale in E. benuensis can all be matched in E. guineensis from Nigeria. Finally the supposed difference in pattern (six white stripes on dorsum in E. benuensis and allegedly five in E. guineensis results from an error in Boulenger's description. Boulenger placed E. guineensis in Eremias sens. lat. because it has the combination of fine dorsal scaling, keeled subdigital lamellae and nostril separated from the first upper labial scale that this author regarded as diagnostic of the genus. But he felt that this species occupied an isolated position within the assemblage and assigned it to a new subgenus, Taenieremias Boulenger, 19186. This separation of E. guineensis from the rest of Eremias sens. lat. appears valid, for it differs in a number of features from the three main groups included in Boulenger's concept of the genus. It can be distinguished from Eremias proper (a Palaearctic assemblage) by having its postorbital and postfrontal bones unfused, by absence of a radially directed peripheral section on scleral ossicle number 14, possession of C-type caudal vertebrae, a reflectable collar and an asymmetrical hemipenis; from members of Mesalina by absence of a radially directed peripheral section of scleral ossicle number 14, absence of an occipital scale, possession of three rows of scales around the digits, which are pectinate, and an asymmetrical hemipenis; and from the Ethiopian species usually referred to Eremias and the probably related Meroles by C-type caudal vertebrae and an asym- metrical hemipenis which differs in detail from any found in that group. It also differs from the great majority of them in its heart-shaped sternal fontanelle and in absence of a peripheral section of scleral ossicle 14 and of an occipital scale. On the other hand, E. guineensis agrees with all the features of Acanthodactylus listed on pp. 293-294 with the exception of the arrangement of scales around the nostril (features 26 & 27). Yet even here the situation in E. guineensis is not very like that found in species assigned to Eremias sens. lat. and in size, shape and pattern of contact with each other, the scales bear a close overall resemblance to those in Acanthodactylus, the only obvious difference being the presence of an extra suture in E. guineensis running across the area occupied by the first upper labial scale in Acanthodactylus to produce a smaller, nominal first upper labial and a subnasal scale that is radically different in form from that found in RELATIONSHIPS OF ACANTHODACTYLUS 297 members of Eremias sens. lat. (Fig. 2). Evidence that the E. guineensis condition is easily derived from that found in Acanthodactylus is provided by a juvenile A. erythrurus lineomaculatus (BM(NH) 1966.430) which, although normal in other respects, possesses an extra suture that virtually duplicates the condition found in E. guineensis (Fig. 2e). In addition to possessing the overwhelming majority of the features found in all or most Acanthodactylus, E. guineensis bears a more detailed resemblance to A. boueti of north Dahomy and Ghana and to A. erythrurus and A. savignyi of northwestern Africa (p. 318). Given this degree of similarity, it seems best to transfer E. guineensis to Acanthodactylus, as suggested elsewhere (Arnold, 1980/?). Characters varying within Acanthodactylus The following features may vary between species of Acanthodactylus and are therefore potentially useful in defining species and in attempting to work out their inter-relationships. Species names mentioned in the course of description are used in the senses employed subsequently in this paper. A summary of many of the features is given in Tables 8 and 9. Osteological characters Shape ofthepremaxillary region (Fig. 3). In many Acanthodactylus the outer edge of the premaxilla (viewed from above or below) is smoothly continuous with those of the maxillae, but in some species this bone is abruptly narrowed and there may be a slight constriction where its lateral surfaces meet the maxillae. Fig. 3 Premaxillary regions of Acanthodactylus skulls from beneath: (left) A. erythrurus — outer edge of maxilla and premaxilla smoothly continuous; (centre) A. schmidti premaxilla abruptly narrowed; (right) A. scutellatus — premaxilla abruptly narrowed and premaxillary teeth reduced to five, pm-premaxilla m-maxilla. This condition is strongly developed in A. blanfordii, A. schmidti, A. arabicus, A. gongrorhynchatus, A. haasi, A. masirae and especially the members of the A. scutellatus group: it is at least indicated in many A. boskianus, A. cantoris and A. opheodurus. A smooth lateral border to the anterior part of the skull is the usual condition in lacertids and the narrowing found in some Acanthodactylus is almost certainly apomorphic. It is best developed in species habitually living on soft sand. These forms usually have very acutely pointed snouts and at least some probe the sand when hunting, perhaps in response to tactile or aural cues originating from hidden invertebrates. Narrowing of the premaxilla may be related to producing the acuminate snout-tip necessary for this activity. Number of premaxillary teeth. The usual number of premaxillary teeth in most Acanthodactylus species is seven with occasional individual variation to six or eight. The three specimens of A. boueti checked are singular in apparently having nine premaxillary teeth while many members of the A. 298 E. N. ARNOLD scutellatus group have only five; this is true of the great majority of A. scutellatus and A. longipes examined but of only a few A. aureus (see p. 328). As the number of premaxillary teeth in most lacertids is about seven to nine, five seems likely to be an apomorphic condition within Acanthodactylus. Its development may well be connected with the narrowness of the premaxilla in these forms. Postorbital and postfrontal bones. These elements are separate in nearly all Acanthodactylus but they are fused in A. cantoris, even juvenile ones. Number ofpresacral vertebrae. There are from 23 to 27 vertebrae between the skull and the sacrum in Acanthodactylus. The interspecific variation encountered during this study is set out in Table 1. From this it will be seen that, in most species, males usually have more presacral vertebrae than females, the average difference in vertebral number between them varying from about 0-66 to 1-23. The main exceptions to this are A. pardalis bedriagai and members of the A. scutellatus group where average sexual differences are very small, ranging from —0-07 to 0-28. Although most populations of A. schmidti show sexual differentiation in count, this is very reduced in populations from the United Arab Emirates, eastern Arabia. In the majority of species, there are 24 presacral vertebrae in most males and 25 in most females, but counts are higher in A. (t.) tristrami, A. (t.) orientalis, A. robustus, A. erythrurus, A. savignyi, A. boueti and A. guineensis: here males typically have about 25 presacral vertebrae against usually 26 or even 27 in females. A. pardalis bedriagai generally has 26 vertebrae in both sexes while in male and female A. schmidti from the United Arab Emirates, A. scutellatus and A. aureus average counts approach 24; the average is even lower in A. longipes and in some parts of its range may be around 23. Nearly all other lacertids show marked sexual variation in vertebral number, so its reduction is likely to be apomorphic. Counts of 23 in males and 23 or 24 in females are at the lower limit for lacertids as a whole and may well be derived conditions. Other counts are well within the normal range for the family but the higher ones, 25 in males, 26 or 27 in females, may possibly also be apomorphic as they commonly occur only in a minority of forms which on other grounds may be closely related. In general, species with high presacral vertebral counts are found in relatively mesic habitats while those with low vertebral numbers occur in drier, more open places with sparser vegetation. It may be that the former habitat type requires more body flexion in passing through plant cover and more vertebrae facilitate this. Certainly in lacertids as a whole there is a distinct if imprecise correlation between vertebral number and habitat structure. The selective pressures that cause loss of sexual differentiation in vertebral number are obscure. Possibly the difference in average count found in most lacertids reflect sex- correlated difference in microhabitat, males might, for instance, spend more time in open situations than females. If this were so, uniformity of vertebral number might result from lack of such microhabitat differences, something that seems quite probable in the relatively uniform, open environments occupied by A. schmidti and the A. scutellatus group. Another possibility is that the extra vertebrae of most female lacertids increase the length of the body cavity for carriage of eggs and that loss of sexual differentiation is a correlate of small clutch mass. However, although egg number in the A. scutellatus group at least is quite small (n = 2 or 3) there is no clear evidence that a clutch occupies a smaller proportion of the body cavity than in most other species of Acanthodactylus. Sternal ribs. In the great majority of Acanthodactylus species the usual sternal rib formula is 3 : 2, that is three pairs of ribs attach directly to the sternum and two to the xiphisternum. However, in nearly all of these, the fifth sternal rib is interrupted on at least one side in a minority of individuals, albeit often only briefly. In contrast, interruption is the commoner condition in RELATIONSHIPS OF ACANTHODACTYLUS 299 H — *° <*- IS 2 •Si 0 3: £ & C — u P o.E tS S t: ^2 js c o ^ £- * "" ' ex P yn ^ so OOO^ r^Ot^m oo -3-00000— • — > c3 r £ O fl) X) « 03 OS O O — — O — — <•"" e "O C 1 r- rs — r^ — (N SO — — , u-^ Tj- ON so — so fN so m — c« P^orit^ ^j-sot^— °nooo\ — — ~»i so iV) — O "-O (N (N 2 ^ ^ D fO ^, «— ro "o i ^ . — r \^ u- ("^ - ^ OS S M «r^ — CO «O •^- ry-j ro so >o ^h O ^ , f\) Or, £ rn <•<•> — SO 00 — "^j Q § 3 -S -S? ^ c"§"^ S 'R P li 'So J 'S '^ ^-^ -d >\>'3'"~',i:Q'-*iSs; "^ ^ Q •^ Oi-s3^i313s3ffCi<'^;->O ^.^ SS •<^<-rp-<^Tr ^r'T'^r'T'^''^'^ •^•^•^•^••^-^^•^-^•^^•^•^T^-^T^ 300 E. N. ARNOLD intra muscular portion of armature medial connectors upper surface of lateral clavula TS of lateral clavula lateral connectors upper surface of medial clavula TS of medial clavula medial clavula lateral lobe reflexed lateral sulcal lip medial lobe reflexed medial sulcal lip medial lip of sulcus sulcus lateral lip of sulcus Fig. 4 Left armature and uneverted hemipenis of Acanthodactylus micropholis, diagramatic view from below, the base of the hemipenis is at the bottom of the illustration. The m. retractor penis magnus and ventral wall of the hemipenis have been removed, the flattened hemipenial lobes spread out and the armature disconnected: normally the points marked A coincide, with the armature lying largely above and behind the retracted hemipenis. members of the A. pardalis and A. scutellatus groups, sometimes overwhelmingly so (Table 1 .) Furthermore, the fifth sternal rib is frequently reduced to quite a small vestige. Hemipenial characters Like many other lacertids, Acanthodactylus has a hemipenis with an armature, that is a discrete and complex supporting structure of dense connective tissue situated mainly in and around the penis retractor magnus muscle. Its basic anatomy and that of the lacertid RELATIONSHIPS OF ACANTHODACTYLUS d e f Fig. 5 Uneverted left hemipenes of Acanthodactylus spp. showing variation in form and symmetry. In all except (b), the lobes are flattened and normally complexly folded, but they have been spread out for illustration, (a) lobes subequal (A. micropholis); (b) lobes subequal but tubular and unflattened (A. cantoris); (c) medial lobe somewhat reduced (A. blanfordii. A. pardalis generally similar); (d) medial lobe very small (some A. (t.) orientalist (e) medial lobe minute, lateral lobe large (e.g. A. schmidti); (f) medial lobe absent, lateral lobe extremely large (e.g. A. scutellatus). hemipenis in general are described elsewhere (Arnold, 1973; and in press) but Fig. 4 shows the salient features in Acanthodactylus. A number of variations between species are described below, and are illustrated in Figs 5 and 6. Size. Hemipenes are small in A. cantoris, A. boueti, A. maculatus and A. spinicauda. Asymmetry in the lobes of the hemipenis. In many species, the two lobes are subequal in size but in others the medial lobe is reduced while the lateral one increases in size and becomes more fan-like in the uneverted organ. The amount of medial reduction varies and in some cases the medial lobe is absent or minute. Lobes subequal: A. micropholis, A. cantoris, A. boskianus, A. schreiberi, A. grandis complex, A. (t.) tristrami, A. robustus, A. erythrurus, A. savignyi, A. boueti. Medial lobe somewhat reduced: A. blanfordii. Medial lobe more strongly reduced: A. pardalis, some A. (t.) orientalis. Medial lobe very small: some A. (t.) orientalis. 302 E. N. ARNOLD Fig. 6 Left armatures of Acanthodactylus species. Main views from beneath; arrangement of distal views of clavulae and of their transverse sections as in Fig. 4: (a) A. cantoris: (b) A. blanfordii', (c) A. schmidti; (d) A. arabicus', (e) A. gongrorhynchattus; (f) A. (t.) tristrami. A number of species have generally similar armatures to A. (t.) tristrami but differ mainly in the form of their lateral clavula, consequently in (g)-(j) only this is shown, ventral and dorsal views and a cross section being given: (g) A. robustus', (h) A. grandis; (i) A. boskianus; (j) A. e. erythrurus, A. pardalis; (k) A. (t.) orientalis; (1) A. guineensis\ (m) A. maculatus; (n) A. scutellatus', (o)A. opheodurus. Medial lobe minute or absent: A. schmidti, A. arabicus, A. gongrorhynchatus, A. haasi, A. guineensis, A. maculatus, A. spinicauda, A. aureus, A. longipes, A. scutellatus, and the A. opheodurus group. Lobe shape. In most Acanthodactylus, the hemipenial lobes are flattened and fan-shaped, but complexly folded in the uneverted organ. However, in A. cantoris they are narrow and tubular. Form of the proximal lip of the medial branch of the sulcus. This is usually well developed and flap-like in species where the medial side of the hemi- RELATIONSHIPS OF ACANTHODACTYLUS 303 penis is relatively large, although it is usually reduced in forms where this is not so. A. boskianus, A. schreiberi and A. grandis are exceptional in having a well-developed median lobe but a weak proximal lip to the medial branch of the sulcus. Reduction of the medial side of the armature. In most species, the medial side of the armature is reduced in size, simpler in form than the lateral side and indeed may be entirely absent. The extent to which this reduction occurs varies and shows some correlation with reduction of the medial lobe of the hemipenis, although how precise this is varies. Sides subequal: A. micropholis, some A. cantoris. Medial side somewhat reduced: some A. cantoris, A. boskianus, A. schreiberi, A. grandis complex, A. (t.) tristrami, A. robustus, A. erythrurus, A. savignyi, A. boueti, A. pardalis. Medial side more strongly reduced: A. blanfordii, some A. schmidti, A. (t.) orientalis. Medial side reduced to a thread or absent: most A. schmidti, A. arabicus, A. gongrorhyn- chatus, A. haasi, A. guineensis, A. maculatus, A. spinicauda, A. aureus, A. scutellatus, A. longipes, A. opheodurus, A.felicis, A. masirae. In these forms the medial branch of the sulcus is short or absent. Shape of the medial clavula. In species where a medial clavula is present there are two main patterns. Clavula fairly broad, flat and blunt-tipped with at least the inner edge turned upwards: A. micropholis, A. cantoris, A. blanfordii and some A. schmidti. Clavula narrow and pointed with a ^ -shaped cross section: A. boskianus, A. schreiberi, A. grandis complex, A. (t.) tristrami, A. robustus, A. erythrurus, A. savignyi, A. boueti, A. pardalis. In A. (tristrami) orientalis the median clavula is like this or very small and flattened. Shape of lateral clavula. Substantial differences are found in the form of this structure. 1 . Simple, flattened, often with one or both edges turned dorsally: A. micropholis, A. cantoris, some A schmidti, A. robustus, A. opheodurus, A.felicis, A. masirae. 2. Not flattened, blunt, edges folded dorsally, a central lobe on the upper surface with a proximally directed pocket: A. blanfordii, many A. schmidti. 3. Very narrow, hollowed above: A. arabicus, A. gongrorhynchatus (A. haasi has a similar but shorter lateral clavula). 4. Complexly structured with multiple lobes below: A. boskianus, A. schreiberi (most medial lobe often single), A. grandis complex (most medial lobe often divided). 5. Complexly structured although not conspicuously lobed below, sometimes very slightly bifurcate: A. (t.) tristrami. 6. Complexly structured and not conspicuously lobed below but clearly bifurcate at tip: A. (t.) orientalis, A. erythrurus, A. savignyi, A. boueti, A. pardalis. 1. Lateral clavula simple but often bifurcate and folded to give a D-shaped cross section: A. maculatus, A. spinicauda. 8. Lateral clavula flattened and not bifurcate but folded to give a ID-shaped cross section: A. aureus, A. scutellatus, A. longipes. Connectors. In some species the connectors are all relatively thin but in others the most medial one on the lateral side is usually thickened. This is found in A. boskianus, A. schreiberi, the A. grandis complex, A. (t.) tristrami, A. (t.) orientalis. A. robustus, A. erythrurus, A. savignyi, A. boueti, A. guineensis, A. pardalis, A. maculatus and A. spinicauda. Polarity of hemipenial features The only available criterion for the polarity of hemipenial features found in Acanthodactylus is outgroup comparison using other lacertids as the outgroup. In these, the hemipenis is 304 E. N. ARNOLD usually fairly large and symmetrical with well developed sulcal lips on both sides. Where present the armature is also typically symmetrical with simple, often flattened and rather blunt clavulae. On this basis, small size, asymmetry of the lobes, sulcal lips and armature and the development of peculiar and often complex clavulae and thickened connectors are all likely to be derived features. Origin of hemipenial differences It is common in many animal groups for genital structure to vary between taxa and for at least some of its features to be considered good indicators of relationship, especially as they often correlate with characters from other organ systems. The origin of such differences and possible reasons why they should often reflect relationship are discussed at length elsewhere (Arnold, 1973; in press). It is suggested that genitals differ from other organ systems in their potential to retain changes that develop in them as a result of pleiotropic effects or transient selective forces. With most organ systems, any pleiotropically induced change is likely to result in a loss of functional efficiency. Provided this lowering or efficiency does not outweigh the original selective advantage of the genetic change concerned, the pleiotropic alteration will initially become fixed. But there will then be normalizing selection modifying the genotype so that the pleiotropic change will tend to be suppressed and the organ will return to its original state and level of efficiency. Similarly, if the organ changes in response to direct but transient selective pressure, it will tend to revert to its original condition once this pressure is relaxed. The situation with genitalia is different since their efficiency cannot be considered in isolation but only in relation to their co-ordinated functioning with the genitals of the opposite sex. Efficiency does not depend on a particular conformation or size but on good match between the sexes. Consequently, if there were, say, a pleiotropic change affecting the male organs which reduces copulatory efficiency, there would not only be normalizing selection acting on the male genotype to bring the male organ back towards its original condition but also, simultaneously, selection acting on the female genotype to produce genital changes adapting to the pleiotropic alterations that have already taken place in the male system. This means that the two sets of genitals might return to their previous mutual efficiency without reverting to their original morphological state. The same sort of effect would be expected if transient selective forces acted directly on the genitalia themselves. Genitals are thus likely to 'store' changes, which in other organ systems would probably be eradicated. So they may be on the whole more likely to incorporate evidence of shared evolutionary experience than many other organs. An important factor in the production of hemipenial differences in lizards, including Acanthodactylus, may be the development of physical isolating mechanisms when pre- viously allopatric species come into contact. Such isolating mechanisms could reduce the loss of reproductive effort which is likely if two species interbreed. That such loss can occur is evidenced by the occasional discovery of hybrids between lacertid species (cases in Lacerta and its relatives are summarized by Arnold, 1973, and in Acanthodactylus by Mertens, 1968). Physical isolating mechanisms would be at a premium in situations where similar species with no experience of each other come into contact since, in this situation, premating isolating mechanisms may not be well developed. Interspecific mating would be reduced if considerable mismatch evolved in the shape and dimensions of the genitalia of the forms concerned. The often radically different hemipenes of otherwise similar species of Acanthodactylus may be examples of this, especially as they correspond in shape and size to the cloacal bursa of their own females into which the male organ is inserted. Such differences occur between forms which, on other grounds, are likely to be closely related, for instance Acanthodactylus pardalis and A. maculatus and, because they reduce the possibility of successful copulation between the forms, are prima facie evidence of separate species status. Some of the derived features found in the hemipenes of Acanthodactylus can be interpreted as contributing to such isolating mechanisms; they include not only small size but also RELATIONSHIPS OF ACANTHODACTYLUS 305 asymmetry of the hemipenis and armature since loss of its medial side reduces the diameter of the organ. Although they are likely to be 'stored' beyond their period of function (presumably premating isolating mechanisms are likely to develop in the long run), changes that are probably associated with physical isolating mechanisms are not likely to be very reliable indicators of relationship. This is partly because, by their nature, they tend to produce marked differences between very similar and often closely related species. Also, means of producing incompatible genitalia are rather restricted in lizards and it is very likely that small size and asymmetry may have been produced several times. This is supported by their patchy occurrence in Acanthodactylus, turning up in a number of groups which on other grounds do not seem to be closely related. Furthermore these features have developed in other lacertid genera. Other hemipenial features may not be subject to such strong convergent selective forces and, as such are more likely to be good indicators of relationship for the reasons given earlier in this discussion. Description of the hemipenes of different species Figures in parentheses refer to the number of individual organs examined. A. micropholis (2). Lobes more or less symmetrical or medial rather reduced, sulcus bifurcate, the proximal borders of its branches formed by backwardly directed flaps; armature fairly symmetrical although one or other clavula larger than the other, clavulae rather expanded and obtusely pointed, the medial one with its inner edge turned upwards, lateral one with both edges turned upwards; often three lateral connectors and two medial ones, all narrow. A. cantoris (7). Size reduced; medial lobe usually rather smaller than lateral, lobes not complexly folded, the walls often corrugated and lack regular plicae, stem of hemipenis long, sulcus bifurcate, the proximal borders of its branches formed by a soft flap in at least some cases although this is not always clear; armature symmetrical or medial side somewhat reduced, slender, the clavulae expanded and laminar, medial with inner edge turned upwards, lateral with both edges turned upwards, at least one connector on each side. A. blanfordii (10). Lateral lobe large and medial one reduced, sulcus bifurcate, proximal border of lateral but not medial side formed by a backwardly directed flap; armature clearly asymmetrical, the median side reduced with a flattened clavula of which the inner edge is turned upwards, lateral clavula large and obtusely pointed, not flattened, edges turned upwards and a central lobe present on the upper side below which there is a proximally directed pocket (the lobe is least developed in southern populations), connectors as in A. micropholis. A. schmidti (10). Lateral lobe large and fan-shaped, medial lobe absent or minute, sulcus bifurcate but medial branch very short; medial side of armature absent or reduced to a thread in most cases; lateral clavula large, either rather pointed, slightly bifurcate or rather blunt, edges turned upwards and clavula may be rolled to some extent, a central lobe present in many cases on the upper side, below which is often a proximally directed pocket as in A. blanfordii but is less well developed. In one case (BM(NH) 1931.7.16.48) there is a flattened medial clavula. A. arabicus (6). Essentially like A. schmidti but intramuscular part of armature much narrower and lateral clavula very narrow, simple and pointed with a concavity above or the medial edge rolled upwards. A. gongrorhynchatus ( 1 ). Similar to A. arabicus but medial edge of clavula rolled onto dorsal surface. 306 E- N. ARNOLD A. haasi (1). Like A. gongrorhynchatus but clavula shorter, broader and more dorso- ventrally flattened. A. (tristrami) tristrami (3). Lobes more or less symmetrical, sulcus bifurcate, the proximal borders of its branches formed by distinct flaps; armature asymmetrical, the medial side reduced with a pointed clavula that has a ^ -shaped cross section; lateral clavula expanded and, when spread out, essentially flat with a very weakly bifurcate tip formed of overlapping laminae, lower surface fairly smooth but with a strap-shaped area with free edges towards outer side, upper surface with a medially directed pocket and edges rolled upwards; three lateral and two medial connectors, the more medial of the lateral ones thickened. A. (tristrami) orientalis (4). Different from A. (t.) tristrami: lateral lobe very large and medial strongly reduced (as in Fig. 5c or d), sulcus bifurcate, proximal borders of branches formed by distinct flaps, the median one rather small; armature very asymmetrical, medial clavula quite small, either pointed with a <= -shaped cross-section or blunt and flattened; lateral clavula rather similar to that of A. (t.) tristrami and has free strap-shaped area on lower surface but is smaller with a more bifurcate tip and no clear pockets. A. robustus (2). Generally like A. (t.) tristrami but lateral clavula much simpler with edges turned on to dorsal surface. A. boskianus (10), A. schreiberi (5). Generally like A. (t.) tristrami but proximal border of medial branch of sulcus is a relatively weak, soft fold rather than a flap; lateral clavula has similar general form but is more swollen and lobed and there is an area with free edges towards the medial side of the ventral surface; upper surface has medial edge rolled upwards and greatly swollen. In A. schreiberi and A. boskianus the median area of the ventral surface may be divided by a longitudinal cleft. A. erythrurus erythrurus (3), A. e. lineomaculatus (3), A. savignyi savignyi (2), A. s. bland (2). Similar to A. (t.) tristrami but lateral clavula usually clearly bifurcate at tip and the more median cleft in A. (t.) tristrami, that separates a strap shaped area with free edges in this form, is usually not clearly marked. A. e. belli (6). As A. e. erythrurus but lateral clavula is smaller, flatter and usually simpler. A. boueti (1). 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"3 •-C} . grandis . (t.) tristrami . (t.) orientalis . robustus erythrurus savignyi -c guineensis pardalis pardi pardalis bedri maculatus spinicauda . aureus . scutellatus . longipes , opheodurus , felicis , masirae ^TpTpTJ-TpTTTlH •'r'^? •^ TJH ^r T]H ^ ^ ^r •^ rp TT TT ^< "^ "^ T rr T* TW 332 E. N. ARNOLD v-> 1 1 1 1 1 1 1 1 1 1 03 03 03 1 1 1 1 1 1 1 1 III III 03^ 03^ ro 1 1 1 1 1 1 1 1 1 1 III 1 1 1 1 fill III III ro rn 1 1 1 eo 1 1 1 1 1 1 e^e- e-. 1 1 1 1 1 1 1 1 MM III & 1 S III III r r i 111 i i i i TIII if 3 i i S 1 1 1 1 1 1 1 i i i 03 03 03 1 1 1 1 1 1 1 1 iii iii O 1 1 1 1 1 1 1 i i i 03 03 03 1 1 1 1 1 1 1 1 iii iii Sx 'o? •> ^^ T JD- N—' 03 03 i r x 1 1 ^ 1 1 1 1 03" 03^ 03" 03 ^Xx ' ' ' 'o? S 1 1 fjD 1 1 1 i i i III 1 1 1 1 1 1 1 1 III III _^ V_x N_^ od od od '**—' & 2- 03 03 03 _< ^ 03 TO '^'^ *^^ O i r i i i i i r r r 111 rx es r i i i i iii iii «) •o o 1 •2 §o 3 a "t2 Q C 8 » — A ~ •fj «s * -i to ^^ 3-5' 8-14? -5 ?•- C 2 e ? o be to •i c §^ a c g 5 a --s ^ ^ o a fc v> -d % a feo-s; schreiberi boskianus grandis -.a "^^ §"« S -2 §,^§^ 11 § §Ki liil i's§ Pi! iis-i .rv "x > «3 •»«* V 5^. r* -.Z ^G o C^os ^^ccx i^^- C <^^^(x .cxc^cto to ^ S *^ >• 2 Q.) ill In III Is I H "^ T T ^ "^ ^ ^ •^ ^ T^ X"^^ TTTX "^XX^ ^ "^ T ^ ^ X RELATIONSHIPS OF ACANTHODACTYLUS 333 V V ""X / T-1b,2.3.5. 19,22\ / 27b. 29, 33 \ / 16 -30.31.35 \ / . 15, 21 c Fig. 9 Tentative hypothesis of the relationships of the species of Acanthodactylus. Figures refer to derived characters listed in Tables 8 and 9. Lines above species names join forms that have a very close overall resemblance, vindicates alternative position for the A. scutellatus group (A. aureus, A. scutellatus and A. longipes). A number of Acanthodactylus species share a distinctive hemipenial structure which incorporates two derived features not found elsewhere: the medial clavula is narrow and pointed with a ^ -shaped cross section (1 1) and the most medial connector on the lateral side is often thickened (17); in addition there is moderate asymmetry of the armature (lOa). This pattern occurs in A. boskianus, A. schreiberi, the A. grandis complex, A. (t.) tristrami, A. (t.) orientalis, A. robustus, A. erythrurus, A. savignyi, A. boueti and A. pardalis. It seems probable that these forms constitute a monophyletic group in Ashlock's (1974) sense within Acanthodactylus. Among them A. boskianus, A. schreiberi and the A. grandis complex all have a reduced proximal lip to the medial branch of the hemipenial sulcus (9) and a lateral clavula that is complexly lobed (14). Within this trio, A. boskianus and A. schreiberi may well be sister species, for some populations are extremely similar. A. grandis shows conflict of evidence as to its relationships. It has some similarity in derived features to members of the A. cantoris group, viz. high number of ventral scales (26) which are tessellated (27b) and four longitudinal rows of scales along the fingers (29b). However, weighting criteria (especially frequent occurrence in groups not closely related to Acanthodactylus} suggest these features are relatively weak indicators of relationship, whereas it has been argued (p. 329) that most of the conflicting hemipenial features (9, 11, 14, 17) that ally the A. grandis complex to A. boskianus and A. schreiberi are likely to be of greater reliability. Moreover, any detailed placement of the A. grandis complex in the A. cantoris group would involve additional homoplasies. Members of the A. tristrami group share features not found elsewhere in the genus, viz. no keeling on the proximal, dorsal caudal scales (30), a short tail (31) and an often distinctive pattern (35). The very similar A. (t.) tristrami and A. (t.) orientalis could well be sister species. A. robustus has some features that suggest relationships elsewhere: subocular scale separated from the mouth (22), increased number of ventrals (26a) and an irregular fourth scale row on the fingers (29a), but none of these derived states is very strongly developed and all seem likely to be relatively weak indicators of relationship compared with those allying A. robustus with A. (t.) tristrami and A. (t.) orientalis. The A. tristrami and A. erythrurus groups share some distinctive features, in particular a high number of presacral vertebrae (4) and fragmented first and fourth supraocular scales 334 E. N. ARNOLD (2 1 c). Furthermore, some species of each have a lateral clavula that is bifurcate at its tip ( 1 5), so it seems reasonable to regard the two assemblages as closely related. The members of the A. erythrurus group are all generally similar and at least some individuals of all species have one or more azygos shields between the prefrontal scales (20) although this condition also occurs occasionally in other forms. It is suggested that A. erythrurus and A. savignyi are sister species on the evidence of their great similarity and frequent division of the frontonasal scale (19). They are also the only members of the group in which the subocular scale may be separated from the lip (22). A. boueti and A. guineensis both have distinctive features of their own (A. boueti — nine premaxillary teeth, fragmented parietal scales, small hemipenis (7), supraocular scales very fragmented (2 Id); A. guineensis — very asymmetrical hemipenis and armature (8d, lOc), lateral clavula rolled) but their precise relationships to each other and to A. erythrurus and A. savignyi are not clear. All A. guineensis examined (n = 20) have a peculiar arrangement of nasal scales (18) which occurs as a rarity in A. erythrurus (p. 296). However, this feature cannot be regarded as strong evidence of the close relationship of these species within the group, for its rarity in A. erythrurus raises the possibility that its apparent absence in A. savignyi and A. boueti may be due to inadequate sampling or to pseudoreversal (Arnold, 198 la). The A. pardalis group seems likely to be a monophyletic assemblage on the basis of the strong overall similarity of its members. They also have more hemipenial asymmetry (8b or 8c) than the species placed in the A. grandis complex and the A. boskianus, A. tristrami and A. erythrurus groups, share a high incidence of interruption of the fifth sternal rib (6) and the number of ventral scales is also regularly high (26). The main reason for allying the A. pardalis assemblage with these groups is that the species with the least modified hemipenis, A. pardalis, has an armature just like the others with derived features lOa, 11 and 17. The absence of these features in the other two species in the A. pardalis group, A. maculatus and A. spinicauda, may be secondary, the result of the development of physical isolating mechanisms (p. 304). The A. pardalis group shares with the A. tristrami and A. erythrurus groups frequent bifurcation of the tip of the lateral clavula (15), some fragmentation of the supraocular scales (2 Ib) and some tendency for high presacral vertebral counts (4). However, the last feature is not universal and the supraoculars are less broken up than in these forms. Because of this, the A. pardalis group is tentatively placed as a sister assemblage to them. Within the A. pardalis group, A. maculatus and A. spinicauda may be closely related having strongly asymmetrical hemipenes and armatures (8d, lOc) with the lateral clavula folded sideways (16). Holophyly of the A. scutellatus group is supported by the close similarity of its members and their possession of a unique synapomorphy; premaxillary teeth reduced to five (2). Its members have several other derived features that occur elsewhere and these suggest conflicting hypotheses as to the closest relatives of the group. The main candidates are A. schmidti, particularly the populations in the United Arab Emirates that have little sexual variation in the number of presacral vertebrae, and all or part of the A. pardalis group. Derived features that these share with the A. scutellatus assemblage are set out in Table 10; the A. grandis complex shares a much smaller number, namely 26, 27 and 29. Most derived features, eleven, are shared with A. schmidti populations from the United Arab Emirates and only seven with the A. pardalis group of which no more than six occur in any one species. Thus on simple count of shared characters A. schmidti would be considered clearly the more likely sister taxon, but the likely quality of the features as indicators of relationship should also be taken into account. In general, the features shared with A. schmidti seem rather weak as they score badly on the weighting criteria listed by Arnold (198 la). For instance, numbers 3, 5, 6, 8d, lOc, 23, 26, 27, 29 and 33 occur in a number of other lacertid stocks; there are additional functional reasons for thinking 8d and lOc may have evolved more than once (p. 304); if the argument on p. 333 that the A. grandis complex is more closely related to the A. boskianus group than to the A. cantoris assemblage is accepted, then characters 23, 26, 27 and 29 must have evolved twice within Acanthodactylus and a third independent origin RELATIONSHIPS OF ACANTHODACTYLUS 335 Table 10 Comparison of derived features shared by the A. scutellatus group with A. schmidti and the A. pardalis group. A. schmidti A. pardalis group Main United Arab A. scutellatus A. maculatus range Emirates group A. pardalis A. spinicauda Ib Premaxilla narrow + + + 3 Presacral vertebrae 23 or 24 in females + + 5b Little variation in number of presacral vertebrae + + + 6 Fifth sternal rib often interrupted + + + 8 Medial lobe of hemipenis very reduced + + + + 1 Oc Medial side of armature very reduced + + + + 1 6 Lateral clavula folded to produce a z> -shaped cross section — + + 23 High number of upper labials + + + + + 26 Increased number ofventrals + + + + + 27 Ventrals tessellated, at least at sides + + + 29 Four scale rows on fingers + + + 33 Young without stripes + + +,— Strong pectination on toes + + + would not seem unlikely; a number of features seem to be functionally related to the problems of living in the open, soft-sand habitats occupied by A. schmidti and the A. scutellatus group, this is true of Ib, 3, 29, 33 and strong pectination on the digits; the coercive selective forces likely to produce convergence of these features are discussed in the relevant character descriptions. Finally, two features, 3 and 5, are confined in A. schmidti to a very small part of the geographical range, the United Arab Emirates. The restricted distribution of these characters suggest they may well have developed independently within the species. If so, the number of features to be considered is reduced to nine. On the other hand the relationship of the A. scutellatus assemblage to the A. pardalis group is supported by an apparently unique hemipenial feature (16) and the high incidence of interrupted sternal ribs, a condition not found elsewhere in the genus. Assessing such conflicting evidence is inevitably difficult but, on balance, the author is inclined to believe that the A. scutellatus group is most closely related to the A. pardalis assemblage. As stated, the members of the A. opheodurus group are placed together largely on the grounds of overall similarity which is especially marked between A. opheodurus and A. felicis. Shared derived features are 8d, lOc and in some individuals of each species 32a; none of these are unique to the group. Evidence for the inter-relationship of the species is conflicting: A. felicis and A. opheodurus share 5a and 22 while the latter species and A. masirae share 1 and 29, although 29 occurs only in a reduced form in A. opheodurus and only in a minority of individuals. The lack of strong derived characters makes it difficult to relate the A. opheodurus group to other Acanthodactylus, but absence of a thickened hemipenial connector (1 7) suggests that it is not directly related to the A. grandis-A. guineensis sequence (see Fig. 9). Nor is it clear how this sequence relates to A. micropholis and the A. cantoris assemblage. 336 E. N. ARNOLD Acknowledgements The author is very grateful to the various collectors who, in the past few years have donated often critical series of Acanthodactylus to the British Museum (Natural History). They include D. Vesey Fitzgerald, M. D. Gallagher, J. and P. Gasperetti, D. J. Greathead, K. M. Guichard, M. C. Jennings, M. R. K. Lambert, J. P. Mandeville, S. Moult, G. V. Popov, T. D. Rogers, T. D. Stoner, W. Thesiger and J. O. Wade. The following curators were kind enough to lend material in their care: E. R. Brygoo, (Museum Nationale d'Histoire Naturelle, Paris), J. Castroviejo and P. W. Hopkins (Estacion Biologica de Donana, Seville), M. S. Hoogmoed (Rijksmuseum van Natuurlijke Historic, Leiden), A. E. Leviton (California Academy of Sciences, San Francisco), C. J. McCoy (Carnegie Museum, Pittsburgh), H. Marx (Field Museum of Natural History, Chicago), F. Tiedemann (Naturhistorisches Museum, Vienna), E. E. Williams and P. Alberch (Museum of Comparative Zoology, Harvard), H. Marx (Field Museum, Chicago). Some of the radiographs used in this study were produced by B. T. Clarke. References Anderson, J. 1895. On a collection of reptiles and batrachians made by Colonel Yerbury at Aden and its neighbourhood. Proc. zool. Soc. 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Reptilien und amphibien aus Syrien. Ber. senckenb, naturf.Ges. 1878-79 : 57-84. Bons, J. & Girot, B. 1962. Revision de 1'espece Acanthodactylus scutellatus (Lacertide-Saurien). Bull. Soc. Sci. nat. Maroc. 42 : 3 1 1-334. Boulenger, G. A. 1 878. Sur les especes $ Acanthodactylus des bords de la Mediterranee. Bull. Soc. zool. Fr.3: 179-201. 1887a. Descriptions of new reptiles and batracians in the British Museum (Natural History) — Part 3. Ann. Mag. nat. Hist. (5) 20 : 50-53. 18876. Catalogue of the lizards in the British Museum (Natural History), vol. 3. London, xii + 575 pp. 1909. Description of a new lizard of the genus Acanthodactylus from Syria. Ann. Mag. nat. Hist. (8)4: 188-189. RELATIONSHIPS OF ACANTHODACTYLUS 337 — 1 9 1 8a. Sur les lezards du genre Acanthodactylus Wiegm. Bull. Soc. zool. Fr. 43 : 143-1 55. — 19186. A synopsis of the lizards of the genus Eremias. J. Zool. Res. 3 : 1-12. — 1918c. Description of a new lizard of the genus Acanthodactylus from Mesopotamia. J. Bombay not. Hist. Soc. 25 : 373-374, — 1919. On a new variety of Acanthodactylus boskianus, Daud., from the Euphrates. Ann. Mag. nat.Hist. (9)3:549-550. 1921. Monograph of the Lacertidae, vol. 2. London, viii + 451. Chabanaud, M. P. 1917. Enumeration des reptiles non encore etudies de 1'Afrique occidentale, appartenant aux collections du Museum, avec la description des especes nouvelles. Bull. Mus. Hist. nat. Paris 191 7: 83-105. Clark, R. J., Clark, E. D., Anderson, S. C. & Leviton, A. E. 1969. Report on a collection of amphibians and reptiles from Afghanistan. Proc. Calif. Acad. Sci. 36 : 279-3 16. Daudin, F. M. 1802. Histoire naturelle . . . . des Reptiles, vol. 3. Paris. Doumergue, F. 1901. Essai sur la faune erpetologique de 1'Oranie. Soc. Geogr. Arch. Oran. 19: 197-260,501-32, Dumeril, A. M. C. & Bibron, G. 1839. Erpetologie generale ou histoire naturelle complete des reptiles, vol. 5, Paris 854 pp. Duvdevani, I. & Borut, A. 1974a. Mean body temperature and heat absorption in four species of Acanthodactylus lizards (Lacertidae). Herpetologica 30 : 1 76-18 1 . 19746. Oxygen consumption and evaporative water loss in four species of Acanthodactylus (Lacertidae). Copeia 1974: 155-164. Elmer, T. 1881. Untersuchungen iiber das Variiren der Mauereidechse, ein Beitrag zur Theorie von der Entwicklung aus constitutionellen Ursachen, sowie zum Darwinismus. Arch. Naturgesch. 47 : 239-517. Flower, S. S. 1933. Notes on the recent reptiles and amphibians of Egypt, with a list of the species recorded from that kingdom. Proc. zool. Soc. Lond. 1933 : 735-85 1 . Gauthier, R. 1967. Ecologie et ethologie des reptiles du Sahara Nord-occidental (region de Beni- Abbes). Annls Mus. roy. Afr. centr. 155 : 1-83. Gray, J. E. 1838. Catalogue of the slender-tongued saurians, with descriptions of many new genera and species. Ann. Mag. nat. Hist. 1 : 274-283. 1845. Catalogue of the specimens of lizards in the collection of the British Museum. London, xxviii + 289. Gugg, W. 1939. Der Skleralring der plagiotremen Reptilien. Zool. Jb. Abt. Anal. 65 : 339-416. Giinther, A. C. L. G. 1864a. Report on a collection of reptiles and fishes from Palestine. Proc. zool. Soc. Lond. 1864:488^93. 1 8646. The reptiles of British India. London, xxvii + 452. 1903. Reptiles from Rio de Oro, Western Sahara. Novit. zool. 10 : 298-299. Haas, G. 1957. Some amphibians and reptiles from Arabia. Proc. Calif. Acad. Sci. 39: 47-86. and Werner, Y. L. 1969. Lizards and snakes from southwestern Asia, collected by Henry Field. Bull. Mus. comp. Zool. Harv. 138 : 327-405. Hennig, W. 1950. Grundzuge einer Theorie der phylogenetischen Systematik. Berlin. 1966. Phylogenetic systematics. Urbana. Lantz, L. A. 1928. Les Eremias de TAsie occidentale. Bull. Mus. Georgie, 4 and 5. Lataste, F. 1881. Diagnosis des reptiles nouveaux d'Algerie. Naturaliste 1881 : 357-59. Leviton, A. E. & Anderson, S. C. 1967. Survey of the reptiles of the Sheikhdom of Abu Dhabi, Arabian Peninsula, part 2. Systematic account of the collection of reptiles made in the sheikhdom of Abu Dhabi by John Gasperetti. Proc. Calif. Acad. Sci. 35 : 157-192. Lichtenstein, M. H. C. 1823. Verzeichniss der Doubletten des Zoologischen Museums der ... Universitdt. Berlin. Matschie, P. 1893. Uber einige von Herrn Oscar Neumann bei Aden gesammelte u. beobachtete Saugthiere, Reptilien und Amphibien. Sbr. Ges. naturf. Freunde Berl. 1893 : 27-31. Mertens, R. 1968. Uber Reptilienbastarde, IV. Senckenberg. biol. 49 : 1-12. 1969. Die Amphibien und Reptilien West-Pakistans. Stuttg. Beitr, Naturk. 197 : 1-96. Milne-Edwardes, M. H. 1829. Recherches zoologiques pour servir a 1'histoire des lezards extraites d'une monographic de ce genre. Ann. Sci. nat. 16 : 50-89. Minton, S. A. 1966. A contribution to the herpetology of West Pakistan. Bull. Am. Mus. nat. Hist. 134 : 27-184. Monard, A. 1949. Vertebres nouveaux du Cameroun. Revue Suisse Zool. 56 : 73 1-745. 338 E. N. ARNOLD Mosauer, W. 1934. The reptiles and amphibians of Tunisia. Publs Univ. Calif. Los Ang. biol. Sci. 1 : 49-64. Pappenfuss, T. J. 1969. Preliminary analaysis of the reptiles of arid central west Africa. Wasmann J. Biol. 27 : 249-336. Pasteur, G. & Bons, J. 1960. Catalogue des reptiles actuels du Maroc. Trav. Inst. sclent, cherif. Serie Zoo/. 21: 1-132. Peters, W. 1854. Diagnosen neuer Batrachier welche zusammen mit der friiher (24. Juli und 17. August) gegedenen Ubersicht der Schlangen und Eidechsen mitgetheilt werden. Monatsb. Akad. Wiss. Berlin 1854 : 614-628. Quesne, W. J. Le, 1969. A method of selection of characters in numerical taxonomy. Syst. Zoo/. 18 : 201-205. Riney, T. 1953. Notes on the Syrian lizard Acanthodactylus tristrami orientalis. Copeia 1953 : 66-67. Rosevear, D. R. 1965. Bats of West Africa. London. Sarnthein, M. 1978. Sand deserts during glacial maximum and climatic optimum. Nature Lond. 272 : 43-46. Schinz, H. R. 1833. Naturgeschichte und Abbildungen der Reptilien. Leipzig, iv + 240. Schmidt, K. P. 1919. Contributions to the herpetology of the Belgian Congo based on the collection of the American Congo Expedition 1 909- 1915. Bull. A m. Mus. nat. Hist. 39 : 3 8 5-624. 1939. Reptiles and amphibians from southwestern Asia. Fieldiana Zoo/. 24: 49-89. Scortecci, G. 1946. Tentative di analisi biologica condotto sulla specie Acanthodactylus scutellatus Audouin. Riv. Biol. colon. 7 : 5-15. Shcherbak, N. N. 1974. Yashchurki Palearktiki. Kiev, 295 pp. Werner, F. 1929. Beitrage zur Kenntnis der Fauna von Syrien und Persien. Zoo/. Anz. 81 : 238-245. Wiegmann, A. F. A. 1834. Herpetologia Mexicana. Berlin, vi + 64 pp. Manuscript accepted for publication 4 August 1982 Addendum Since this paper was submitted for publication, I have had the opportunity to see the recent article on Acanthodactylus by Dr Alfredo Salvador. (1982). In the main, we are in agreement over species boundaries within the genus and a number of the divergencies that exist can be attributed to using different criteria for deciding if allopatric populations merit species status or not, always a rather subjective decision. These and other more important disagreements are briefly considered below. 1. The A. yemenicus group of Salvador is the same as the A. opheodurus group of Arnold (19806 and this paper) but with the addition of a new taxon, A. yemenicus. This form has much in common with A. felicis. Unlike the other members of the group, its specific status cannot be confirmed by sympatry, as its range is completely separate from the others. There are considerable differences between the two populations from which A. yemenicus has been described, Ta'izz and the Sheikh Osman-Aden area, even although these are only separated by some 1 30 km. 2. A. erythrurus group. Salvador treats bland as a full species rather than a subspecies of A. savignyi. Given the differences between this form and typical savignyi, this course is not unreasonable. 3. A. pardalis group. A. pardalis, as understood here, is divided by Salvador into three full species: A. p. pardalis becomes monotypic as A. pardalis, A. p. bedriagai becomes A. bedriagai and the Moroccan population related to bedriagai becomes A. busacki n. sp. These forms overlap in many morphological features. 4. A. tristrami sens. lat. Salvador regards A. tristrami, in its wide sense, as consisting of two subspecies: A. t. tristrami, with which A. t. orientalis is synonymized, and A. t. iracensis. This contrasts with the arrangement adopted here where orientalis is regarded as separable from tristrami and iracensis is synonymized with orientalis. A careful examination of the types of all three forms and of most other available material convinces me that the latter course is more appropriate. A. t. iracensis cannot be separated from orientalis on the basis of the RELATIONSHIPS OF ACANTHODACTYLUS 339 features mentioned by Schmidt (1939), namely lower transverse dorsal count, less vivid colour pattern and more sharply pectinate toes; nor does it differ significantly in any of the other features investigated. On the other hand, typical tristrami differs from orientalis, including iracensis, not only in its larger size, more numerous dorsal scales and hemipenial structure, but usually also in its deeper snout with convex upper profile, absence of a denticulation on the anterior edge of the ear and virtual lack of pectination on the toes. In addition, the first supraocular is more fragmented (tristrami-n— 10, average number of fragments on each side 5.4, range 3-10; orientalis-n= 17, average number of fragments on each side 2.8, range 1-6). 5. A. scutellatus group. Salvador divides A. scutellatus, as understood here, into A. scutellatus in the east and A. dumerilii in the west. The two supposed species are said to approach each other in Mali and Algeria but not to integade. I have re-examined the BM(NH) material from Mali that Salvador assigns to A. scutellatus and A. dumerilii and can find no differences in the features that are said to separate them, namely transverse ventral count, snout shape and number of rows of supraciliary granules. Where A. scutellatus and A dumerilii approach each other around the Algerian-Tunisian border, I again find no consistent differences in snout shape as mentioned by Salvador, and although there are average differences in degree of fragmentation of the fourth supraocular scale, there is substantial overlap. I consequently regard the separation of A. dumerilii from A. scutellatus as unproven. Salvador divides his A. dumerilii into two subspecies: A. d. dumerilii in Senegal, southwest Mauretania and Mali and A. d. exiguus in Algeria and Morocco. The former is said to have 12 instead of 14 longitudinal rows of ventral scales, two instead of one row of supraciliary granules and longer legs. In material I have examined, I find that two rows of supraciliary granules are often absent in the area where A. d. dumerilii is reported and leg length is variable. Furthermore, there is a very large intergrade area between the two subspecies where other characters vary clinally. It scarcely seems worth while naming such poorly defined entities, especially when A. scutellatus varies so substantially elsewhere in its large North African range and no subspecies names are assigned. 6. The diagnosis of Acanthodactylus given on p. 8 does not fully differentiate the genus from Meroles or Eremias. Salvador, A. 1982. A revision of the lizards of the genus Acanthodactylus (Sauria: Lacertidae). Bonn, zool. Monogr. 16: 1-167. British Museum (Natural History) 1881-1981 Centenary Publications Chance, change & challenge Two multi-author volumes from one of the foremost scientific institutions in the world. General Editor: P. H. Greenwood The Evolving Earth Editor: L. R. M. Cocks The Evolving Biosphere Editor: P. L. Forey In the first volume, The Evolving Earth, twenty scientists have been asked to review the present state of knowledge in their particular field, ranging from the origin of the Earth, through ocean sediments and soils to continental drift and palaeogeography. In the companion volume, The Evolving Biosphere, museum scientists have chosen an evolutionary concept — speciation, coevolution, biogeography etc. and related this to the group of animals or plants in which they are specialising. Thus beetles and birds exemplify sympatric and allopatric speciation, butterflies mimicry and certain fishes explosive evolution. In both volumes the text is supplemented by over one hundred specially-commissioned pieces of two-colour artwork. These two books will be invaluable to all sixth-form and undergraduate biology and geology students. The Evolving Earth: 276x219 mm, 280pp, 138 line illustrations, 42 halftones The Evolving Biosphere: 276x2 19 mm, approx. 320pp, 133 line illustrations Published: May 1981 Co-published by the British Museum (Natural History), London and Cambridge University Press, Cambridge. Titles to be published in Volume 44 Observations on the systematics of the genus Difflugia in Britain (Rhizopoda, Protozoa). By Colin G. Ogden Miscellanea A review of the Euplotidae (Hypotrichida, Ciliophora). By Colin Curds & Irene C. H. Wu The Opthalmotilapia assemblage of cichlid fishes reconsidered* By Peter Humphry Greenwood Osteology, genitalia and relationships of the Acanthodactylus (Reptilia: Lacertidae). By E. N. Arnold 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) Morphological studies on some Difflugiidae from Yugoslavia (Rhizopoda, Protozoa) Colin G. Ogden & Andjelija Zivkovic Zoology series Vol 44 No 6 30 June 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 Vol44No6pp341-375 British Museum (Natural History) Cromwell Road London SW7 5BD Issued 30 June 1983 Morphological studies on some Difflugiidae from Yugoslavia (Rhizopoda, Protozoa) Colin G. Ogden Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD Andjelija Zivkovic Institute for Biological Research, University of Belgrade, 29, Novembra 142, 11000 Belgrade, Yugoslavia Contents Introduction 341 Materials and methods 341 Systematic descriptions 342 Difflugia 342 Cucurbitella 369 Pontigulasia 369 Summary 373 References 374 Introduction Recent studies (Ogden, 1979, 19800, b, 1983; Ogden & Fairman, 1979) on the shell morphology of specimens belonging to the family Difflugiidae, have shown that detailed examination of these structures aid identification at the species level. It is now possible using the scanning electron microscope to demonstrate differences in shell structure and to examine more easily the type and arrangement of materials used in these complex con- structions. Earlier workers were handicapped in similar examinations by the limited resolution of reflective optical microscopy. This made comparisons of shell structure difficult due to the different densities of the shell ranging from opaque to transparent, and sometimes the shape made a complete survey impracticable, ovoid or circular shells being particularly awkward. The present work is based on specimens collected in Serbia, Yugoslavia, from an area of peat bogs located on the high plateau at 1200 m, now submerged by the artificial lake 'Vlasina', which was formed by damming the river Vlasina and flooding a depression. A limnological study of this lake by Milovanovic & Zivkovic (1956) gives information relating to the chemical and biological conditions during the initial formation of this feature. There are several reasons for our interest in the Difflugiidae of Yugoslavia, no previous records of testate amoebae are available for this region, there appears to be a similarity of this fauna with that reported from Africa by Gauthier-Lievre & Thomas (1958) and specimens of the so-called 'cosmopolitan' species are available for comparison with those already described from the British Isles. Furthermore, the presence of several compressed species of Difflugia is unusual, as these forms appear to be rare. Materials and methods Samples were collected in September, 1947 from a pond 'Godzina bistrica' located at the Bull. Br. A/MS. nat. Hist. (Zool.) 44(6) : 34 1-375 Issued 30 June 1 983 342 C. G. OGDEN & A. 2lVKOVIC margin of a peat bog, and preserved in formalin. The samples were divided into two in 1980, one half was deposited in the Zoology Department, British Museum (Natural History) and the other was retained in Yugoslavia. This report is based mainly on the BM(NH) specimens but reference is also made to those in the other sample. Selected shells from the sample were washed in several changes of distilled water, then individuals were prepared for scanning electron microscopy using the technique described by Ogden (1979). The prepared stubs were examined using a Cambridge Stereoscan SI 80 operating at 10 kV and the results recorded on Ilford HP5 film. Systematic descriptions The species ofDifflugia are listed in alphabetical order, except for the new species which are described last and D. gramen which is described with D. schurmanni for comparative purposes. The single species of the genus Cucurbitella and two species of Pontigulasia are described after the species of Dijflugia. The measurements for total body length includes aboral processes, unless otherwise stated, breadth and diameter of aperture are taken as the widest point, the latter is an internal measurement. Genus DIFFLUGIA Leclerc, 1815 Difftugia acuminata Ehrenberg, 1838 A single specimen, 199 urn long, 85 urn in breadth, with an aperture diameter of 37 urn, was examined and seen to be identical to those already described (Ogden, 1979). Significantly the distinctive organic cement pattern of this species, a network in which each mesh is further divided by a smaller network, was present. Difflugia acutissima Deflandre, 193 1 DESCRIPTION. The shell is transparent, pyriform with the sides tapering evenly from about the mid-body region and terminating usually with a sharp point (Fig. la). It is composed mainly of flattish pieces of quartz to give a smooth surface, with organic cement sometimes seen as part of the shell matrix (Fig. Ic). The cement is usually in the form of a network about 400 nm in diameter with walls 200 nm thick, and each mesh is covered by a smooth membrane (Fig. Id). The aperture is circular and surrounded by small to medium particles (Fig. Ib). One specimen had an oblique aperture and a misaligned aboral protuberance (Fig. le), the latter being only partially sealed (Fig. 10, but was considered to agree with the general description of this species in all other respects. MEASUREMENTS (in um). Four specimens: body length 178-217, breadth, 80-107, diameter of aperture 47-51. GEOGRAPHICAL DISTRIBUTION. Argentina (Dioni, 1970), Chad (Gauthier-Lievre & Thomas, 1958), Congo (Chardez, 1964), Gold Coast, Morocco (Gauthier-Lievre & Thomas, 1958), United States of America (Leidy, 1879), Venezuela (Deflandre, 1931). REMARKS. This species was initially described by Deflandre (1931) who considered that it was distinct from D. acuminata and its varieties by the sharpness of the aboral extremity. It differs from D. ventricosa, also described by Deflandre (1926) from Venezuela, by having a much wider body and aperture. The general body dimensions are similar to those given for D. distenda by Ogden (1983), which was a variety of D. acuminata but this species is curved aborally to a small tubular horn. The problems of differentiating between species with aboral horns or spines are emphasized in two publications by Chardez (1961 & 1973), which show several figures supposedly pertaining to the same species. It is clear that concise specific DIFFLUGIDAE FROM YUGOSLAVIA 343 Fig. 1 Difflugia acutissima : a, lateral view x600; b, apertural view x360; c, detail of organic cement pattern x 14000; d, portion of shell surface to show organic cement between particles X 6600; e, specimen with oblique aperture and non-central aboral spine x 420; f, detail of partial closure at extremity of aboral spine x 1900. 344 C. G. OGDEN & A. 2IVKOVIC identification of specimens must await morphogenetic evidence of natural variation of this feature within a species. Difflugia bicornis Penard, 1890 DESCRIPTION. The shell is transparent, ovoid or spherical with usually two, but occasionally one aboral spines (Figs 2a & b). Of the three specimens examined only one had a single long aboral spine. The surface is rough, thin and composed of a mixture of small to medium particles of quartz, with the occasional addition of either a portion of diatom frustule or a siliceous flagellate cyst. Each aboral spine is roughly pointed and composed of small particles. A network of organic cement is sometimes seen between particles (Fig. 2d). It is in the form of a sheet with each mesh being separated by small walls, about 80 nm thick. The mesh is irregular, about 300-400 nm in diameter, and each enclosure often has a small inner circular wall with arms connecting it to the mesh wall (Fig. 2e). The aperture is usually circular and surrounded by a mixture of particles (Fig. 2c). MEASUREMENTS (nm). Three specimens: body length 75-85, breadth 39-53, diameter of aperture 19-23. GEOGRAPHICAL DISTRIBUTION. Germany (Penard, 1890; Jung, 1936), Guatemala, Mexico (Laminger, 1973), Switzerland (Penard, 1902). REMARKS. This species was initially described as a distinct species by Penard (1890) but was later considered (Penard, 1902) to be a small form of D. elegans, and he illustrated the vari- ability of the shell in this form with several figures, including specimens with either one or two aboral spines. The specimens reported here have a fragile shell and are in good agree- ment with the original description of D. bicornis, the body lengths without the spines or horns being about 60 um which is near to Penard's 50-60 urn. The contrast between these specimens and those of D. elegans studied recently (Ogden, 1979), which had robust shells and varied in body length between 1 1 3-1 58 um, is marked. In the absence of information on other small forms identified as D. elegans, we have decided to use the earlier description of D. bicornis and consider the present specimens as a distinct species. Difflugia bryophila (Penard, 1902) A single specimen, 124 um in body length, 53 um broad with an aperture diameter of 1 7 um. It was identical to those described by Ogden (1 983). Difflugia capreolata Penard, 1 902 DESCRIPTION. The shell is opaque, thick, pyriform with a restriction of the neck at a position about one-third of the total body length, before it swells into the main body (Fig. 3a). It is composed of small to medium pieces of angular quartz, with small areas of organic cement as part of the matrix (Fig. 3c). This cement is in the form of a smooth sheet with irregular perforations (Fig. 3d), the reason that there is no apparent pattern to these perforations may be due to these areas being in thin strips rather than a more open arrangement. Each perforation has a mean diameter of 200 nm. The aperture is circular and surrounded by a regular distribution of medium particles (Fig. 3b). MEASUREMENTS (in um). One specimen: body length 225, breadth 128, diameter of aperture 58. GEOGRAPHICAL DISTRIBUTION. Argentina (Dioni, 1970; Lena & Zaidenwerg, 1975), Germany (Schonborn, 1965), Russia (Kourov, 1925), Tunisia (Gauthier-Lievre & Thomas, 1958), Sudan (Gauthier-Lievre & Thomas, 1958), Switzerland (Penard, 1902). REMARKS. This species although it is large and has a distinctive outline, does not appear to be common and is rarely found in large numbers. DIFFLUGIIDAE FROM YUGOSLAVIA 345 Fig. 2 Difjlugia bicornis: a, lateral view of specimen with two aboral spines x 1400; b, lateral view of specimen with single aboral spine x 760; c, apertural view x 820; d, portion of shell surface to illustrate the organic cement (arrowed) x7500; e, detail of organic cement x 35000. 346 C. G. OGDEN & A. 2IVKOVIC Fig. 3 Difflugia capreolata: a, lateral view x400; b, apertural view x340; c, shell surface showing small areas of organic cement x 3000; d, detail of organic cement pattern x 1 3000. Difflugia corona Wallich, 1864 DESCRIPTION. The shell is brown, spherical or ovoid with distinct cone-like spines projecting from the aboral half of the body (Fig. 4a-d). The main body is composed of a mixture of small to medium particles of quartz arranged to give a relatively smooth shell. The spines are randomly arranged, varying between two and eight in number, made of small particles and are usually finely pointed. Organic cement in the form of a network is sometimes seen where particles meet. The aperture is circular and surrounded by a distinct denticular collar. There DIFFLUGIIDAE FROM YUGOSLAVIA 347 , , ^~'-^~ r^%£'j^^& Fig. 4 Difflugia corona: a, lateral view of specimen with six spines x430; b, apertural view of a, note the regular arrangement of twelve teeth x 330; c, lateral view of another specimen x 240; d, apertural view of c, to show sixteen thickened teeth x 240. are usually between ten to twelve tooth-like projections, although one specimen in the present sample had sixteen (Fig. 4d). They are arranged evenly, usually being finely pointed, but as seen in Fig. 4d compression of the teeth makes the projections thicker and the outer curvature of the collar more rounded. MEASUREMENTS (in um). Fourteen specimens: body length 126-190, breadth 126-177, diameter of aperture 53-86. GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Argentina (Boltovskoy & Lena, 1974; Lena & Ziadenwerg, 1975; Vucetich, 1970), Austria (Laminger, 1975), Belgium (Chardez, 1961, 1980), Brazil (Green, 1975), British Isles (Ogden & Hedley, 1980; Wallich, 1864), Chad (Gauthier-Lievre & Thomas, 1958), Congo (Chardez, 1964; Gauthier-Lievre & Thomas, 1958), Czechoslovakia (Ertl, 1965), Germany (Penard, 1890), Hungary (Bereczky, 1973), India (Wallich, 1864), Java (BartoS, 1963), Netherlands (Hoogenraad & Groot, 1940), Roumania (Godeanu et al, 1973), Russia (Kourov, 1925), 348 C. G. OGDEN & A. 2IVKOVIC • Fig. 5 Difflugia difficilis: a, lateral view x 950; apertural view x 760; c, detail of aperture to show short collar and organic cement (arrowed) between particles x 2 100; d, detail of organic cement x 18000. Senegal, Sudan and West Africa (Gauthier-Lievre & Thomas, 1958), South Africa (Oye, 1931), Switzerland (Penard, 1902), United States of America (Leidy, 1879). REMARKS. This species is truly 'cosmopolitan' having been reported from most continents, but these sightings are probably due to the ease in observing the prominent features of this large, distinctive shell in any sample. Although Jennings (1916, 1937) showed that variation of both teeth and spines occurred under cultural conditions, subsequent authors have continued to designate forms and varieties based on these structures. It could be argued that Jenning's observations were made on rough cultures and that clonal cultures would behave differently, or that the medium used was limiting in some way. Nevertheless, some of the reported features could easily be considered to represent natural variation. DIFFLUGIIDAE FROM YUGOSLAVIA 349 Difflugia decloitrei Godeanu, 1 972 A single specimen similar to those recently described by Ogden (1983) was found. It is possibly an encysted form as the aperture was blocked with several flat pieces of quartz bound by organic cement. MEASUREMENTS (in um). One specimen: body length 79, breadth 52, diameter of aperture 22. Difflugia difficilis Thomas, 1954 DESCRIPTION. The shell is transparent, ovoid, thin with a small apertural collar (Fig. 5a). It is composed of small to medium pieces of angular quartz arranged to make a relatively smooth surface, with the occasional projection of some particles. A network of organic cement is frequently seen as part of the shell matrix (Fig. 5c). The mesh of this network is open, each opening being about 350 nm wide with dividing walls 200 nm thick (Fig. 5d). A short collar made mainly of regularly arranged smallish particles, surrounds the circular aperture (Figs 5b & c). MEASUREMENT (in um). One specimen: body length 8 1 , breadth 56, diameter of aperture 18. GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Argentina (Lena & Zaidenwerg, 1975), Congo (Chardez, 1964), France (Thomas, 1954), Ivory Coast (Gauthier-Lievre & Thomas, 1958), Roumania (Godeanu et al, 1975), Sudan (Gauthier- Lievre & Thomas, 1958). REMARKS. This specimen has similar dimensions to those given for D. difficilis and D. kabylica by Gauthier-Lievre & Thomas (1958). It differs from D. kabylica in having a smaller aperture which does not have a flattened irregular outline. It is most similar to D. difficilis, although it does not have 'une excoissance peu proeminente' as initially described by Thomas (1954). However this species was later reported (Gauthier-Lievre & Thomas, 1958) to vary a great deal in body outline and often the aboral protuberance is absent. The feature that is characteristic of this species is the small collar and in the absence of further specimens the present specimen is considered to be D. difficilis. Difflugia gramen Seep. 357. Difflugia labiosa Wailes, 1919 Two specimens of this species identical to those recently redescribed by Ogden (1983) were found. MEASUREMENTS (in um). Two specimens: body length 176 & 177, breadth 111, diameter of aperture 45 & 52. Difflugia lata Jung, 1942 Difflugia oblonga forma lata Jung, 1942 DESCRIPTION. The shell is opaque, pyriform having a rough surface composed of a mixture of mainly small to medium pieces of quartz, with an occasional large particle added (Fig. 6a). One specimen has a curved or malformed aboral extremity (Fig. 6c), but in all other respects is similar to the original description. Organic cement in the form of a network is seen as part of the shell matrix (Fig. 6d). The mesh of the network is open and has a mean diameter of 350 nm with walls 200 nm thick, although the walls often fuse to give larger areas of cement (Fig. 6e). The aperture is circular and surrounded by both small and medium particles arranged to give a somewhat irregular outline (Fig. 6b). 350 C. G. OGDEN & A. ZlVKOVIC Fig. 6 Dijjlugia lata: a, lateral view x 590; b, apertural view x 420; c, specimen with malformed aboral extremity x 400; d, shell surface with organic cement as part of matrix x 3600; e, detail of organic cement x 13500. MEASUREMENTS (in urn). Two specimens: body length 137 & 149, breadth 90 & 103, diameter of aperture 42 & 46. GEOGRAPHICAL DISTRIBUTION. Chile (Jung, 1942). REMARKS. This species is known apparently only from the initial description (Jung, 1942) as a new form of D. oblonga. Although measurements are not given in the original text, from DIFFLUGIIDAE FROM YUGOSLAVIA 351 Fig. 7 ••••^^^^^^^^•••••^^^^^^^••••••••••••••••^^^•l •••••••••••••••••••••••••''•••I Difflugia levanderi: a, lateral view x730; b, apertural view x530; c, portion of shell surface with organic cement (arrowed) x 7000. the figure these are estimated to be body length 157 um, breadth 81 urn and diameter of aperture 43 urn, which agree well with the present specimens. Note that our Fig. 6c compares well with that given by Jung (1942). This species is considered to be distinct from D. oblonga (see Ogden, 1979) in its stout pyriform body, wide aperture and organic cement pattern. Difflugia levanderi Playfair, 1918 DESCRIPTION. The shell is ovoid or almost spherical, composed of flattish and angular pieces of quartz to give a regular outline (Fig. 7a). The particles appear to overlap and produce a robust structure with a network of organic cement, which is seen infrequently, binding the particles (Fig. 7c). Details of the surface are restricted because all the examined specimens have a slight covering of small debris, this latter material is clearly no part of the shell structure. The aperture is circular, well defined and surrounded by small particles (Fig. 7b). MEASUREMENTS (in um). Five specimens: body length 95-104, breadth 76-92, diameter of aperture 32-40. GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Australia (Playfair, 1918), Chile (Jung, 1942), Morocco and Tunisia (Gauthier-Lievre & Thomas, 1958). REMARKS. The descriptions of both Levander (1894) and Playfair (1918) refer to specimens having a similar shape but differing in size and composition. The larger being robust with a coarse appearance, whilst the smaller had a chitinous shell with a scattering of particles. Unable to differentiate them Playfair (1918) described them as a new species D. levanderi. C. G. OGDEN & A. 2IVKOVIC Fig. 8 Difflugia lismorensis: a, latero-apertural view x 640; b, apertural view to illustrate the thickened teeth and collar x470; c, part of shell surface with overlay of extraneous material X 3400. Fortunately, he created a precedence by initially describing the larger specimens, which are now considered to represent D. levanderi. Specimens similar to D. levanderi except for being smaller and having a thin shell whose particles did not overlap, were described by Godeanu (1972) as a new species D. decloitrei, and these are considered to be identical to the smaller animals described by Levander (1894), Playfair (19 18) and redescribed by Ogden (1983). Difflugia lismorensis Playfair, 1918 Difflugia lismorensis var. quinquelobata Gauthier-Lievre & Thomas, 1958 Difaugia lismorensis var. elongata Gauthier-Lievre & Thomas, 1 958 DIFFLUGIIDAE FROM YUGOSLAVIA 353 DESCRIPTION. The shell is either elongate or ovoid, thick, composed of small to medium pieces of quartz arranged to give a rough surface (Fig. 8a). All the specimens examined had a proportion of the surface covered with an overlay of small extraneous material (Fig. 8c), nevertheless, the portions of actual surface visible had only strands of organic cement as part of the shell matrix. The aperture has five lobes which are equally spaced, strong, blunt, tooth-like extensions (Fig. 8b). Often the strengthening around these lobes, usually with small particles, gives it a collar-like appearance (Fig. 8b). MEASUREMENTS (in um). Three specimens: body length 132-144, breadth 96-104, diameter of aperture 3 6-4 5. GEOGRAPHICAL DISTRIBUTION. Argentina (Vucetich, 1970), Australia (Playfair, 1918), Brazil (Green, 1973), Chad (Gauthier-Lievre & Thomas, 1958), Congo (Chardez, 1964; Gauthier- Lievre & Thomas, 1958), Gold Coast, Morocco and Sudan (Gauthier-Lievre & Thomas, 1958). REMARKS. Playfair (1918) described D. lismorensis as having an ovoid or sub-globular shell with a six-lobed aperture, and added two varieties trilobulata and crucifera which had three and four lobes respectively. Since that time two more varieties with five lobes, from Africa, have been described by Gauthier-Lievre & Thomas (1958). They suggested the name quinquelobata for the ovoid variety and elongata for the specimens with an elongate body, the former has subsequently been reported again in Africa by Chardez (1964). Vucetich (1970) after examining about 50 specimens with seven lobes from Argentina, concluded that these were otherwise identical with D. lismorensis and she did not consider that differences in the number of lobes warranted specific designation. Until examples of this species from Australia, Africa and South America are compared, we agree with Vucetich (1970) that her specimens, plus those of Gauthier-Lievre & Thomas are best described as D. lismorensis. Difflugia lithophila (Penard, 1902), Gauthier-Lievre & Thomas, 1958 Difflugia hydrostatica var. lithophila Penard, 1902 A single specimen identical to that described by Ogden & Hedley (1980) was examined. It is slightly smaller than previous records being 93 um in body length, 67 urn breadth and having an apertural diameter of 32 um; however, it is proportionally similar. African specimens appear to have a larger range of body length, 100-170 um (Gauthier-Lievre & Thomas, 1958), to those from Europe 99-1 40 um (Penard, 1902; Thomas, 1954). Difflugia lucida Penard, 1 890 A single specimen was examined, it measured 61 um in body length, 39 um broad, 19 um depth with an aperture diameter of 22 um. Although slightly smaller than those examined in an earlier study (Ogden, 1983) it was otherwise identical. Difflugia manicata Penard, 1 902 Two specimens 76 & 78 um long, 39 & 43 um in breadth, with aperture diameters of 14 & 17, were examined and found to be identical to those recently redescribed by Ogden (1983). Difflugia mica Frenzel, 1892 DESCRIPTION. The shell is brownish, spherical or ovoid sometimes with a shallow apertural collar (Fig. 9a). It is composed of flattish pieces of quartz arranged to give a relatively smooth surface, although one specimen has most of the surface obscured by extraneous material. Organic cement is seen infrequently between particles but is more evident around the aperture. The cement around the aperture is apparent as a thin layer on the surface of some outer particles (Fig. 9c), but is a concentration of strands, some apparently fused, on the 354 C. G. OGDEN & A. 2IVKOVIC Fig. 9 Difjlugia mica: a, lateral view showing the arrangement of flattish particles x 1400; b, apertural view x 1 100; c, organic cement at outer limit of apertural concentration x 17000; d, concentration of organic cement on apertural lip, note the fusion of some strands x 20000; e, general appearance of organic cement network x 29000. DIFFLUGIIDAE FROM YUGOSLAVIA 355 f Fig. 10 Difflugia nodosa: a, apertural view x270; b, view to illustrate lateral compression x 160; c, lateral view showing the lateral wings and aboral protuberance x970; d, portion of shell surface close to aperture, note that the organic cement is torn (arrowed) x4600; e, & f, detail of organic cement pattern x 14000 & x 2 1000. apertural lip (Fig. 9d). The general structure is of a network with an irregular mesh about 300 to 500 nm in diameter, with dividing walls about lOOnm thick (Fig. 9e). The aperture is circular, well denned, usually with an organic margin and sometimes with a collar (Fig. 9b). MEASUREMENTS (in um). Two specimens: body length 55 & 60, breadth 46 & 55, diameter of aperture 19 & 18. 356 C. G. OGDEN & A. 2lVKOVIC REMARKS. These specimens are in good agreement with the description given by Ogden (1983). They are described again here to include information of the organic cement pattern. Difflugia microclaviformis (Kourov, 1925) The two specimens examined here fall within the range of body lengths given by Kourov (1925) of 139-1 60 um, their respective measurements are: — body length 141 & 163 urn, breadth 66 & 75 um and diameter of aperture 19 & 21 um. Furthermore, they are in good agreement with the recent redescription of slightly larger specimens given by Ogden (1983). Difflugia nodosa (Leidy, 1879) comb. nov. Difflugia pyrif or mis var. nodosa Leidy, 1879 and in Penard, 1902 Dijflugia oblonga var. nodosa Leidy, 1 879 in Gauthier-Lievre & Thomas, 1958 DESCRIPTION. The shell is thick, opaque, pyriform with the main body compressed to give two large lateral wings and an aboral extension or protuberance (Figs lOb & c). It is composed of a mixture of various sized pieces of quartz, which unfortunately in the present specimen is overlaid with debris. Nevertheless, some organic cement was observed close to the aperture (Fig. lOd); it is in the form of a network with the open mesh having a mean diameter of 200 nm and walls 200 nm thick (Figs lOe & f)- The aperture is circular and surrounded by a regular arrangement of small particles (Fig. 1 Oa). MEASUREMENTS (in um). One specimen: body length 367, breadth 241, depth 140, diameter of aperture 53. GEOGRAPHICAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Belgium (Chardez, 1980; Chardez & Gaspar, 1976), Congo (Gauthier-Lievre & Thomas, 1958), Germany (Laminger, 1973; Schonborn, 1962), Ivory Coast (Gauthier-Lievre & Thomas, 1958), Netherlands (Hoogenraad & Groot, 1940), Roumania (Godeanu et al, 1973), Russia (Kourov, 1925), Sudan (Gauthier-Lievre & Thomas, 1958), United States of America (Leidy, 1879). REMARKS. This species has consistently been described as a variety of/), oblonga, initially Leidy (1879) remarked that it was a 'striking variety' distinguished by its unusually large size, compressed body and three conical eminences which varied a great deal in their develop- ment. Although Leidy (1879) reported it as being abundant on one particular occasion, so that one drop of ooze contained several dozen individuals, since that time no other reports have been so fruitful with specimens. Nevertheless, we consider that this variety is best treated as a distinct species which differs from the typical D. oblonga in the features described above and the organic cement pattern. Difflugia oblonga Ehrenberg, 1838 Two specimens with the typically rough shell recently redescribed by Ogden & Fairman (1979) were examined; they measured: body length 232 & 263 um, breadth 1 12 & 109 um and diameter of aperture 46 & 41 um. Difflugia parva (Thomas, 1954) The specimens of this species agree well with the redescription given by Ogden (1983) having a relatively smooth shell and areas of organic cement as part of the shell matrix; body length 143-203 urn, breadth 78-94 urn and diameter of aperture 24-32 um. Difflugia pristis Penard, 1902 Four specimens, body length 37-62 um, breadth 27-38 um and diameter of aperture 13-16 um, having shells composed mainly of quartz particles but with some added diatom frustules, were examined. DIFFLUGIIDAE FROM YUGOSLAVIA 357 Difflugia pulex Penard, 1902 Two small ovoid specimens, body length 30 & 32 um, breadth 22 & 24 um with diameter of aperture 10 & 1 1 um were examined. Difflugia rubescens Penard, 1 89 1 Two specimens, body length 5 & 62 um, breadth 34 & 40 um and diameter of aperture 1 5 um were examined. Difflugia gramen Penard, 1902 DESCRIPTION. The shell is transparent or light brown, spherical tapering towards the aperture (Fig. 1 la). It is composed of a mixture of small to medium pieces of quartz, bound by an organic cement network (Fig. lie). A ring of small pores surrounds the aperture (see Ogden, 1 980b) which is trilobed and bordered by an irregular raised rim (Fig. 1 1 b). MEASUREMENTS (in um). See Table 1 . REMARKS. A brief description of this species is included so that a direct comparison can be made with specimens of Difflugia schurmanni Oye, 1 932 described below. Table 1 Range of measurements (in um) of four ovoid species of Difflugia. n Length (L) Breadth (B) Diameter of aperture (da) B/L da/L da/B D. achlora 2 (E) 49-54 43^6 16-17 D. schurmanni 20 (Y) 50-70 36-52 18-26 0 74 ±0-05 0 35±0-04 0 •48 ±0-03 D. gramen 24 (Y) 69-90 51-81 26-32 0 84±0-08 0 36+0-03 044 + 0-04 D. gramen 35 (E) 89-117 70-112 23-39 0-96+0-07 0 34±0-04 0 36 ±0-03 D. lobostoma 44 (E) 123-186 106-166 32-60 0 87±0-06 0 29 ±0-03 0 33 ±0-02 n = number of specimens; E = Norfolk, England (see Ogden, 1 9806); Y = Yugoslavia (present work) Difflugia schurmanni Oye, 1 932 DESCRIPTION. The shell is transparent, elongate ovoid, tapering equally to the aperture and aboral extremity (Fig. 1 Id). It is composed mainly of flattish pieces of quartz arranged to give a smooth and rather fragile appearance. The particles are bound by organic cement, similar to that described for D. gramen, but because the particles fit closely together cement is not seen as frequently as in that species. The aperture is trilobed with the dividing projections less pronounced in apertural view (Fig. lie) compared with those of D. gramen, and this gives it a more open outline especially as the shell has a smaller breadth (see Table 1). In addition, the surrounding ridge is often not as well defined although in lateral view the lobes are more prominent (Fig. 1 Id). A ring of small pores surrounds the aperture, similar to those described for D. gramen (see Ogden, 19806). MEASUREMENTS (in um). See Table 1. GEOGRAPHICAL DISTRIBUTION. Brazil (Green, 1975), Congo (Gauthier-Lievre & Thomas, 1958), Guatemala (Laminger, 1973a), Senegal (Gauthier-Lievre & Thomas, 1958), South Africa (Oye, 1932), Sudan (Gauthier-Lievre & Thomas, 1958). 358 C. G. OGDEN & A. ilVKOVIC K- •r:f ;<;"*'. •ry-^'^t *'-^/; ;r 4 'H Fig. 11 Difflugia gramen: a, lateral view x 1000; b, apertural view, note the small aperture opening but well denned surrounding ridge x610; c, detail of organic cement pattern x7500 Difflugia schurmanni; d, lateral view, note the different arrangement of particles and denned apertural lobes x 1500; e, apertural view to illustrate wide opening and less pronounced ridge xlOOO. DIFFLUGIIDAE FROM YUGOSLAVIA 359 REMARKS. Reports of this species appear to be confined to tropical countries, but this may be due to it being reported elsewhere as D. gramen. The measurements of specimens for the three similar species, D. achlora, D. gramen and D. lobostoma, redescribed recently (Ogden, 1980&) from England are listed in Table 1 for comparison. It would appear that the information given does not help to resolve specific identification, which still depends on the measurement of overall body length and differences in shell structure. The significance of these latter features must await morphological studies on clonal cultures. D. schurmanni is considered to be distinct from D. gramen in being smaller, more elongate, having a smooth surface composed of flattish particles and a more open aperture. Difflugia smilion Gauthier-Lievre & Thomas, 1958 DESCRIPTION. Unfortunately the only specimen was broken during preparation. The shell is transparent, elongate with a distinct aboral conical protuberance. It is composed mainly of medium to large, angular or flat pieces of quartz to give a rough surface. Organic cement is seen at the junctions of these particles as enclosed spheres, or spheres with small openings, or as a thick rimmed circle with four equal openings (Fig. 12b & c). The spheres are about 600 nm in diameter, the walls of the circle are about 1 50 nm thick and the internal openings vary between 1 50-220 nm. The aperture is circular and surrounded mainly by medium sized particles (Fig. 12a). Fig. 12 Difflugia smilion: a, apertural view to show arrangement of surrounding particles; b & c, detail of organic cement pattern x 2 1 000 & x 1 3000. Table 2 Range of measurements (in um) of D. tuberculata and D. wailesi Length Breadth Diameter of n (L) (B) aperture (da) B/L da/L da/B D. wailesi (i) 20 (Y) 84-1 1 1 63-103 27-40 0 85 + 0-09 0 32+0-03 0 38 + 0-01 D. wailesi (ii) 19 (Y) 73-103 62-82 22-28 0 8310-07 0 3010-03 0 36 + 0-02 D. wailesi 6 (E) 96-112 79-90 29-34 0 •80 + 0-03 0 30 + 0-01 0 38 + 0-02 D. tuberculata 6 (Y) 96-116 74-94 31-35 0 •82 + 0-05 0 3110-02 0 •37 + 0-03 D. tuberculata 27 (E) 102-152 88-141 29-44 0 •89+0-10 0 •29 + 0-04 0 •33+0-02 n = number of specimens; (i) = typical specimens with indented aperture; (ii) = specimens with circular aperture; E = Norfolk, England (see Ogden, 1 9806); Y = Yugoslavia (present work) 360 C. G. OGDEN & A. ZlVKOVIC GEOGRAPHCAL DISTRIBUTION. Algeria (Gauthier-Lievre & Thomas, 1958), Argentina (Dioni, 1970), Belgium (Chardez, 1980; Chardez & Caspar, 1976), Brazil (Green, 1975), Congo (Chardez, 1964), France (Thomas, 1953, 1954), Ivory Coast (Gauthier-Lievre & Thomas, 1958), Poland (Moraczewski, 1965), Roumania(Godeanu^a/., 1973). REMARKS. This specimen is similar in all respects to the description given by Thomas (1953), the body length being about the same, 226 urn, although here it is an estimated figure because of the state of the specimen. No value is given for the breadth, but it was seen to be only slightly larger than the aperture which has a diameter of 4 1 u,m. Dijflugia tuberculata (Wallich, 1864) Specimens with the typical protuberances were examined and the measurements are included in Table 2. Dijflugia wailesi Ogden, 1980 Difflugia tuberculata var. minor Wailes, 1919 DESCRIPTION. Two distinct forms of this species are present in the examined material, both are figured and described. In the typical form the shell is transparent, ovoid but tapering slightly near the aperture (Fig. 13a). It is composed mainly of flattish pieces of quartz and siliceous elements arranged to give a smooth surface (Fig. 1 3a). The aperture is polygonal with usually five but occasion- ally six indentations and bordered by a small lip (Fig. 13b). A ring of about ten small pores is often seen just posterior to the apertural rim. In the other form the shell is ovoid but more markedly tapered towards the aperture (Fig. 13c). The aperture is circular with no indentations (Fig. 13d), but with a similar small ridge as in the typical form. There are nine or more small tooth-like projections inside the apertural rim on a level with the main body of the shell (Fig. 13e), these tooth-like structures are similar to those sometimes seen at the apex of each apertural projection in the polygonal aperture specimens. MEASUREMENTS (in um). See Table 2. REMARKS. The similarity of dimensions between the present specimens and those reported recently from Norfolk, England, highlight the difficulty of differentiating the two species D. tuberculata and D. wailesi. A further division of D. wailesi is not desirable unless supported by strong morphological evidence, therefore, although the specimens are reported as two groups no particular significance is attached to these differences. Difflugia balcanica sp. nov. DESCRIPTION. The shell is transparent, ovoid or roughly circular with an aboral cone or spine and laterally compressed, the shape resembles either an arrow-head or a leaf (Figs 14a & c). It is composed of a mixture of small to large pieces of mainly flattish quartz, arranged to give a relatively smooth but irregular surface, unfortunately the illustrated specimen has some overlying debris scattered on the anterior third of the body. An open network of organic cement is seen between the particles. The aperture is roughly circular and surrounded by small or medium pieces of quartz (Fig. 14b). MEASUREMENTS (in um). Two specimens: body length 1 1 1-1 14, breadth 79-82, depth 50, diameter of aperture 3 1 . REMARKS. There does not appear to be any prior descriptions of any similar compressed species of Difflugia, and D. balcanica is considered to be distinct in having a leaf-like shape, with an angular surface and a pointed aboral extremity. DIFFLUGIIDAE FROM YUGOSLAVIA 361 Fig. 13 Difflugia wailesi: a, lateral view of typical specimen x 760; b, apertural view of a, note the six indentations x470; c, lateral view of elongate specimen x 1 100; d, apertural view of; c, to show circular aperture and surrounding collar x 720; e, detail of teeth on inner rim of circular aperture x5100. 362 C. G. OGDEN & A. 2lVKOVIC Fig. 14 Difflugia balcanica sp. nov.: a, view to illustrate general outline with aboral pro- tuberance x570; b, apertural view x620; c, lateral view to show compression, note the tapering at the apertural and aboral extremities x 460. Difflugia bistrica sp. nov. DESCRIPTION. The shell is ovoid or roughly circular, thin and laterally compressed (Fig. 15a & b). It is composed of medium flattened pieces of quartz with smaller particles between to give a smooth surface (Fig. 15d). Small areas of organic cement occur infrequently, and are usually in the form of a network (Fig. 1 5e). The aperture is a regular oval and surrounded by small particles (Fig. 1 5c). MEASUREMENTS (in um). One specimen: body length 104, breadth 84, depth 54, diameter of aperture 38. REMARKS. Although this specimen has an encrustation of small debris, which is not part of the shell matrix (see Fig. 15d), it is still possible to describe the surface as smooth. This species is similar to D. balcanica in dimensions and degree of compression, but differs signifi- cantly in having a rounded, smooth shell which is curved gently at the aboral extremity. Notwithstanding that this description is based on a single specimen, it is still considered to represent a distinct species and is so designated. Difflugia dragana sp. nov. DESCRIPTION. The shell is opaque, elongate ovoid, thick, tapering gradually from the mid-body position to a gracefully curved aboral extremity and anteriorly to the suggestion of a small apertural collar, it is laterally compressed (Figs 16a & b). Medium pieces of quartz appear to make up most of the surface with smaller particles added. Only small strands of organic cement have been seen (Fig. 16d) between these particles. The aperture is circular and surrounded by mainly small particles of quartz (Fig. 16c). MEASUREMENTS (in um). One specimen: body length 195, breadth 1 19, depth 96, diameter of aperture 48. DIFFLUGIDAE FROM YUGOSLAVIA 363 Fig. 15 Difflugia bistrica sp. nov.: a, lateral view to show regular, circular shape x 760; b, view to illustrate lateral compression, note the gentle aboral curvature x 720; c, apertural view showing oval-shaped aperture x 660; d, portion of shell surface to show flat particles overlaid with extraneous debris x 2900; e, organic cement (arrowed) partially obscured by debris x 13000. 364 C. G. OGDEN & A. 2lVKOVIC Fig. 16 Difflugia dragana sp. nov.: a, lateral view to illustrate the general outline x490; b, view of lateral compression to show gradual curving at both extremities x 320; c, apertural view x 400; d, part of shell surface with strands of organic cement (arrowed) x 9400. REMARKS. This compressed specimen is similar to D. lingula Penard, 1911, D. avellana Penard, 1890 and D. hiraethogii Ogden, 1983. It differs from D. lingula and D. avellana which have pyriform shells, because of the narrow, elongate body which is almost cigar- shaped in lateral view (Fig. 16b), and wide aperture. Although it is most similar to D. hiraethogii, it lacks the distinct neck of this species and is again more elongate and not evenly compressed. D. dragana is considered to be distinct in having an elongate, compressed shell with a wide aperture. DIFFLUGIDAE FROM YUGOSLAVIA 365 Fig. 17 Difflugia serbica sp. nov.: a, lateral view of specimen encrusted with extraneous debris x680; b & c, additional specimens to illustrate the variations of tapering x310 & 240; d, apertural view x420; e, view to show lateral compression x400; f, detail of organic cement network x 21000. 366 C. G. OGDEN & A. 2IVKOVIC ETYMOLOLGY. This species is named after Dragana Dorothea Zivkovic, who has been most helpful in correcting the language shortcomings of both authors. Difflugia serbica sp. nov. DESCRIPTION. The shell is opaque, shaped like a spear-head, tapering evenly from the body to the pointed aboral extremity and gradually, anteriorly towards the short apertural collar, it is laterally compressed (Figs 1 7a-e). The body is composed mainly of medium to large flattish pieces of quartz with a mixture of small to medium pieces at the aperture and aboral extremity. Although the surface is usually smooth, two of the specimens are covered with a layer of small particular debris which appears to have been added after the shell was con- structed (Fig. 1 7e). The organic cement is not frequently seen but is in the form of a network, the mesh being about 400 nm in diameter with walls 50 nm thick, each mesh being covered (Fig. 1 70- The aperture is circular and usually surrounded by small particles (Fig. 1 7d). Fig. 18 Difflugia serbica sp. nov. Diagrams of four specimens to show the variation in outline. MEASUREMENTS (in um). Five specimens: body length 169-189, breadth 110-113, depth 68-79, diameter of aperture 31-41. REMARKS. The dimensions of five specimens from the Yugoslavian sample were somewhat larger: body length 180-280, breadth 1 10-160, depth 75-1 15 (only two measured), diameter of aperture 40-70. Nevertheless, they demonstrate a similar variability in general shape and structure (Fig. 18). This species is similar to D. soudanensis Gauthier-Lievre & Thomas (1958) and D. kempyi Stepanek, 1953 in general dimensions, but both of these species have a distinct apertural collar, are curved aborally and have a median pronounced spine or horn. Furthermore, of these two species only D. soudanensis is compressed. Difflugia serbica is considered to be distinct in having an irregular spear-shaped shell which is laterally compressed, with the suggestion of a small apertural collar and usually pointed aborally. Difflugia serrata sp. nov. DESCRIPTION. The shell is transparent, ovoid, composed of small to medium flattish particles DIFFLUGIDAE FROM YUGOSLAVIA 367 a Fig. 19 Dijjlugia serrata sp. nov.: a, lateral view, note the serrated apertural margin x 1300; b, apertural view x 930; c, portion of shell surface with organic cement (arrowed) x 9400. of quartz arranged to give a smooth surface (Fig. 1 9a). Organic cement is seen as small strands or as a smooth sheet, with regular perforations about 50 nm in diameter (Fig. 1 9c). The aperture is circular with a slight irregular or serrated margin (Figs 19a & b). MEASUREMENTS (in um). One specimen: body length 66, breadth 56, diameter of aperture 28. REMARKS. This species is distinct from other ovoid species of similar dimensions, like D. 368 C. G. OGDEN & A. 2lVKOVIC Fig. 20 Dijflugia styla sp. nov.: a, lateral view to illustrate the aboral spine and smooth surface X 700; b, apertural view x 960. Fig. 21 Difflugia elegans. Illustrations of four specimens, the typical constriction of the neck can be seen in a. minuta Rampi, 1950 and D. pristis Penard, 1902 which have recently been redescribed by Ogden (1983), in having a thin smooth shell and a wide aperture. It is most similar to D. pristis, but the more ovoid or rounded shell, with a large and serrated aperture serve to distinguish D. serrata. Difflugia styla sp. nov. DESCRIPTION. The shell is transparent, ovoid with a distinct aboral spine (Fig. 20a). It is composed of small to medium flattish pieces of quartz, and a network of organic cement is often seen around the aperture as part of the shell matrix. Elsewhere on the surface the organic cement is seen as strands between particles. The aperture is circular and surrounded by smallish particles (Fig. 20b). DIFFLUGIDAE FROM YUGOSLAVIA 369 MEASUREMENTS (in um). One specimen: body length 97, breadth 54, diameter of aperture 29. REMARKS. This species is similar to D. elegans or D. bicornis (see p. 000) in having a single aboral spine or horn. However, both of these latter species are described as having a rough, irregular surface made of angular quartz particles and diatom frustules. In addition, D. elegans has a slight constriction of the neck which gives the aperture a flared appearance (Ogden, 1979), and it was found in the Yugoslavian portion of the sample to show these features (Fig. 21). Although D. styla shares similar dimensions to D. serrata (see p. 000) the presence of an aboral spine separates these species. D. styla is distinct in being elongate ovoid with an aboral spine, and having a smooth shell composed of flat particles. Genus CUCURBITELLA Penard, 1902 Cucurbitella vlasinensis sp. nov. DESCRIPTION. The shell is brown or opaque, subcircular or ovoid, with a distinct apertural collar (Fig. 22a). It is composed of a mixture of small to medium pieces of quartz to give a rough surface, but arranged so that the outline is more or less regular. The particles are packed close together (Fig. 220, with only small areas of organic cement visible. The cement is in the form of a network whose mesh is covered by a smooth membrane (Fig. 22e). The collar is trilobed and composed of small pieces of quartz arranged randomly (Fig. 22b). A double thickness of particles strengthens the three tooth-like projections where they form a dividing barrier with the inner apertural opening; these 'teeth' are usually well denned and composed of small particles. Each lobe has a small recess or cavity so that the internal opening is smaller than the external collar, the floor of these recesses appears as a con- tinuation of the shell matrix (Fig. 22d). The apertural opening is trilobed in sequence with the collar and lined with flattish pieces of quartz with smaller pieces filling the junctions (Fig. 22c). MEASUREMENTS (in um). Forty-one specimens: body length 81-1 13, breadth 69-97, diameter of collar 36-5 1 , depth of collar 9-16, diameter of aperture 1 9-35. REMARKS. In a review of the genus Cucurbitella by Gauthier-Lievre & Thomas (1960) the number of lobes surrounding the aperture was used to differentiate species into a number of varieties and forms. More recently, Ogden (19806) considered that the three and four lobed specimens of C. mespiliformis were otherwise identical in all but that feature, and should therefore be designated as a single species until adequate morphological information was available on the variability of lobe formation. Nevertheless, observations on the many speci- mens of the present sample show that there is little or no variation in the number and shape of the lobes. C. vlasinensis is similar to C. modesta Gauthier-Lievre & Thomas, 1960 and C. modesta forma trilobata Gauthier-Lievre & Thomas, 1960. It differs from C. modesta, which has four lobes, in that feature and general measurements, and from C. modesta forma trilobata in having well-defined teeth, a more extensive inner lining to each lobe and in over- all larger general dimensions. An interesting ecological point to note is that C. modesta forma trilobata was reported only from Morocco which has similar climatic conditions to the region of Yugoslavia where the present samples were collected. ETYMOLOGY. This species is named after the location where the samples were collected, Lake Vlasina, and which, after a visit by both authors in 1 982, has become especially significant. Genus PONTIGULAS1A Rhumbler, 1895 Pontigulasia bryophila Penard, 1902 DESCRIPTION. The shell is pyriform, tapering from the aperture to the slightly swollen posterior third of the body (Fig. 23a). It has a rough surface composed of a mixture of quartz particles with an occasional diatom frustule added. Organic cement is seen at the junctions C. G. OGDEN & A. 2IVKOVIC Fig. 22 Cucurbitella vlasinensis sp. nov.: a, lateral view x 830; b, apertural view x 540; c, view to illustrate the arrangement of particles around the collar x 1200; d, detail of aperture to show tooth-like projections and smaller internal opening x 1200; e, detail of organic cement (arrowed) x 1 3000; f, portion of shell surface showing the close packing of particles x 1 500. DIFFLUGIDAE FROM YUGOSLAVIA 371 Fig. 23 Pontigulasia bryophila: a, lateral view x 470; b, view inside external aperture to show the internal aperture opening (arrowed), micrograph obtained by 'expanded contrast' facility x4100; c, apertural view x760; d, detail of organic cement to illustrate the smaller irregular network of each mesh enclosure x 29000. between particles as a network. This network has a mesh about 600 nm in diameter separated by walls 200 nm thick. Each enclosure has a smaller irregular network over its surface (Fig. 23d). The external aperture is small, surrounded by small or medium particles often arranged to give a serrated or tooth-like margin (Fig. 23c). The single, internal aperture is roughly circular (Fig. 23b) and positioned about a quarter of the body length from the external aperture. MEASUREMENTS (in urn). See Table 2. REMARKS. This species is similar in general appearance to Difflugia bryophila but may be distinguished from it by the presence of an internal aperture and a different organic cement pattern. The present specimens are similar in most respects to specimens of P. bryophila found in England (C.G.O. pers. observ.) except for a difference in organic cement patterns. This feature alone is not considered sufficient for specific recognition. 372 C. G. OGDEN & A. ZlVKOVIC Pontigulasia montana sp. nov. DESCRIPTION. The shell is pyriform, bluntly rounded aborally for one-third of its length and usually tapering gradually from the widest point towards the aperture (Fig. 24a), although sometimes there is a distinct constriction at the position of the internal aperture (Fig. 24c). It is composed of a mixture of mainly medium to large pieces of quartz arranged to give a rough surface. Organic cement is often seen as part of the shell matrix (Fig. 24d), in the form of an Fig. 24 Pontigulasia montana sp. nov.: a, lateral view of specimen without neck constriction x 730; b, apertural view with the internal aperture arrowed x 730; c, lateral view of specimen with distinct neck constriction x430; d, portion of shell surface showing organic cement as part of the shell matrix x4400; e, detail of organic cement network x 14000. DIFFLUGIDAE FROM YUGOSLAVIA 373 open network with walls 200 nm thick and a mesh diameter of 400 nm (Fig. 24e). The external aperture is roughly circular and surrounded by small or medium particles randomly positioned to give it an irregular margin (Fig. 24b). The smaller, single, internal aperture is also circular and surrounded by small particles overlaid with organic cement. MEASUREMENTS (in um). See Table 3. Table 3 Range of measurements (in um) of two species ofPontigulasia Diameter Diameter Length Breadth of external ofinternal n (1) (B) aperture (da) aperture B/L da/L P. bryophila 4 99-146 52-66 18-21 11-14 0-52 + 0-05 0-15+0-03 P. montana 5 91-125 68-81 28-32 15-18 0-6910-07 0-28±0-03 REMARKS. The specimens described here are similar to Pontigulasia bryophila Penard, 1902, but the latter species has a more streamlined, elongate shell, with smaller internal and external openings, plus a distinct organic cement pattern. Comparison of the measurements given in Table 3 emphasizes the difference in body and apertural size between these two species, furthermore, P. bryophila appears to be the only previously described species of Pontigulasia with a single internal aperture. ETYMOLOGY. This species is named after the geographical topography surrounding Lake Vlasina, which is mountainous (L. montana). Summary The information provided by this study extends our knowledge of the family Difflugiidae, in particular the finding of compressed species of Difflugia. The scarcity of these forms is perhaps highlighted by the review of African species in which Gauthier-Lievre & Thomas (1958) list twelve compressed species, of these nine were new, out of a total of one hundred and thirty-three. Thirty-three species of Difflugia are listed here of which thirteen are re- described, including two former varieties of D. oblonga — namely D. lata and D. nodosa, six new species are described — D. balcanica, D. bistrica, D. dragana, D. serbica, D. serrata and D. styla the first four having compressed shells. In addition, two other new species are described — Cucurbitella vlasinensis sp. nov. and Pontigulasia montana sp. nov. It has been mentioned before (Ogden, 19806) that the size and shape of the aperture in pyriform species of Difflugia is a relatively uniform character, but in ovoid specimens appears more variable as shown here in the description of D. lismorensis. Morfoloska studija nekih Difflugiidae iz Jugoslavije (Rhizopoda, Protozoa) REZIME Podatke date u ovom radu prosiruju nasa znanja o familiji Difflugiidae, narocito u pogledu otkrivanja pljosnatih vrsta Difflugia. Retkost ovih vrsta mozda se najbolje ogleda u radu o africkim vrstama, Gauthier-Lievre i Thomas (1958), u kome je dat spisak od ukupno 133 vrsta; medju njima je dvanaest pljosnatih vrsta, od kojih je devet novih. Ovaj rad sadrzi spisak od tridesettri vrste Difflugia, od kojih su trinaest ponovo opisane, ukljucujuci i dya ranija varijeteta: D. oblonga, odnosno D. lata i D. nodosa, a opisano je i sest novih vrsta — D. balcanica, D. bistrica, D. dragana, D. serbica, D. serrata i D. styla, od kojih prve 374 C. G. OGDEN & A. 2IVKOVIC cetiri poseduju pljosnate ljusture. Opisane su i dve nove vrste — Cucurbitella vlasinensis sp. nov. i Pontigulasia montana sp. nov. U ranijim publikacijama ukazano je (Ogden, 19806) da su velicina i oblik pseudostoma u piriformnim vrstama Difflugia relativno konstantna, medjutim, pojavljuje se veca vari- jabilnost u ovoidnim uzorcima, kao sto je slucaj u D. lismorensis. Prouceni materijal sakupljen je 9 septembra 1947. godine iz jedne bare sa prostrane sfagnumske tresave na Vlasini (1200 m) koja je izgradnjom akumulacionogjezera izcezla. References Bartos, E. 1963. Rhizopoden einiger moosproben aus Java. Ada Univ. Carol, 1 19-190. Bereczky, M. C. 1973. Beitrage zur Kenntinis der im Eprofundal des Balaton lebenden testaceen. Annales Univ. Sclent, bpest Rolando Eotvos (Sect. Biol.) 15:1 17-127. Boltovskoy, E. & Lena, H. 1974. Tecamebas del Rio de la Plata. Armada Argentina, H660 32 pp. Cash, J., Wailes, G. H. & Hopkinson, J. 1919. The British Freshwater Rhizopoda and Heliozoa. Vol. IV. Supplement to the Rhizopoda. The Ray Society, London. 1 30 pp. Chardez, D. 1961. Sur Difflugia acuminata Ehrenberg (Rhizopoda, Testacea). Bull. Inst. agron. Stns. Rech. Gembloux29 : 301-308. 1964. Thecamoebiens (Rhizopoda, Testacea). Expl. hydrobiol. Bangweolo-Luapula 10 (2): 1-77. 1973. Sur Difflugia ventricosa Deflandre, 1926 (Rhizopode, 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, C. 1976. Thecamoebiens aquatiques du domaine des Epioux (Ardenne, Belgique). Biol. Jaarb. 44 : 86-100. Deflandre, D. 1926. Notes sur quelques Rhizopodes et Heliozoaires du Venezuela. Bull. Soc. zool Fr. 51: 51 5-530. 1931. Thecamoebiens nouveaux ou peu connus. 1 . Annals. Protist. 3 : 81-95. Dioni, W. 1970. Taxocenos de tecamebianos en cuencas islenas del Parana Medio 1. Acta zool. lilloana 21: 201-240. Ertl, M. 1965. Zur Kenntnis der Testaceenfauna der slowakischen Reisfelder. Hydrobiologia 26 : 13-20. Frenzel, J. 189 . Untersuchungen iiber die mikroskopische Fauna Argentiniens. I. Die Protozoen. I & II Rhizopoden und Helioamoeba. Bibliotheca Zoologica, Stuttgart 12 : 162 pp., X pi. Gauthier-Lievre, L. & Thomas, R. 1958. Les genres Difflugia, Pentagonia, Maghrebia et Hoogenraadia (Rhizopodes, testaces) en Afrique. Arch. Prostistenk. 103 : 241-370. & 1 960. Le genre Cucurbitella Penard. Arch. Protistenk. 104 : 569-602. Godeanu, S. 1972. Especes nouvelles de thecamoeniens (Protozoa, Rhizopodea, Arcellinida). Revue roum. Biol. (Ser. Zool.) 17 : 227-236. Godeanu, S., Godeanu, M. & lonescu, V. 1973. Variata anualS a planctonului din incinta indiguita Obretin (Delta DunSrii). Peuce 3:21 1-260. Green, J. 1975. Freshwater ecology in the Mato Grosso, Central Brazil, IV. Associations of testate Rhizopoda,/. nat. Hist. 9 : 545-560. Hoogenraad, H. R. & Groot, A. A. de 1940. Fauna van Nederland Vol. 9. Zoetwaterrhizopoden en Heliozoen. 302 pp. Leiden. 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 morphogenic activities of rhizopod protoplasm. J. exp. Zool. 77 : 287-336. Jung, W. 1936. Thekamoben urspriinglicher, lebender deutscher Hochmoore. Abh. Landesmus. Prov. Westf. 1 (4): 3-80. 1942. Siidchilenische Thekamoben (Aus dem siidchilenischen Kiistengebiet, Beitrag 10), Arch. Protistenk. 95 : 253-356. Kourov, O. 1925. Faune rhizopodique des bassins de Kossino. Trudy kosin. biol. Sta. 2 : 43-68. Laminger, H. 1973. Die Testaceen (Protozoa, Rhizopoda) einiger Hochgebirgsgewasser von Mexiko, Costa Rica und Guatemala. Int. Revue ges. Hydrobiol. 58 : 273-305. 1975. Die Sukzession der Testaceen-Assoziationen (Protozoa, Rhizopoda) im rezenten und subfossilen Sphagnum des Obersees bei Lunz (Niederosterreich). Hydrobiologia 46 : 465-487. DIFFLUGIDAE FROM YUGOSLAVIA 375 Leidy, J. 1879. Freshwater Rhizopods of North America in Vol. 12. United States Geological Survey of the Territories. 324 pp. Washington. Lena, H. & Zaidenwerg, S. J. 1975. Tecamebas del delta del Parana (Argentina). Revta esp. Micropaleont. 1 : 519-537. Levander, K. M. 1894. Materialien zur Kenntniss der Wasserfauna in der Umgebung von Helsingfors, mil besonderer beriicksichtigung der Meeresfauna. I. Protozoa, Acta Soc. Fauna Flora Few?. 12 No. 2: 1-H5. Milovanovic, D. & Zivkovic, A. 1956. Limnolska ispitivanja baraznog jezera na Vlasini. Zborn. Rad. Inst. Ekol. Biogeogr. 1 (5) : 1^7. Ogden, C. G. 1979. Comparative morphology of some pyriform species of Difjlugia (Rhizopoda). Arch. Protistenk. 122 : 143-153. 1980a. Shell structure in some pyriform species of Difflugia (Rhizopoda). Arch. Protistenk. 123:455^70. 19806. Notes on some Difflugiidae from Norfolk (Rhizopoda, Protozoa). Bull. Brit. Mus. nat. Hist. (Zool.) 39: 125-138. 1983. Observations on the systematics of the genus Difflugia in Britain (Rhizopoda, Protozoa). Bull. Brit. Mus. Nat Hist (Zool.) 44 : 1-73. Ogden, C. G. & Fairman, S. 1979. Further observations of pyriform species of Difflugia (Rhizopoda). Arch. Protistenk. 122 : 372-381. Ogden, C. G. & Hedley, R. H. 1980. An Atlas of Freshwater Testate Amoebae. British Museum (Natural History), London & Oxford University Press, Oxford. 222 pp. Oye, P. van 193 1 . Rhizopoda from South Africa. Rev. Zool. hot. afr. 21 : 54-73. 1932. Neue Rhizopoden aus Africa. Zool. Anz. 99 : 323-328. Penard, E. 1890. Etudes sur les Rhizopodes d'eau douce. Mem. Soc. Phys. Hist. Nat. Geneve 31 : 1-230. 1891. Rocky Mountain Rhizopods. Am. Nat. 25 : 1070-1083. 1902. Faune Rhizopodique du Bassin du Leman. Geneve. 700 pp. 191 1. On some Rhizopods from Sierra Leone. J. Quekett. microsc. Club Ser. II. 11 : 299-306. Playfair, G. J. 1 9 1 8. Rhizopods of Sydney and Lismore. P roc. Linn. Soc. N.S. W. 42 : 633-675. Rampi, L. 1950. Su alcuni Laghetti Alpini del Massiccio dell'Abisso (Alpi Marittime). Boll. Pesca Piscic. Idrobiol. 26 : 207-224. Schonborn, W. 1965. The sediment-inhabiting Testacea from some Masurian Lakes. Acta _ Protozool. 3 : 297-309. Stepanek, M. 1953. Rhizopoda jako biologicke indikatory znecisteni vod. Priord. Shorn. Ostravsk. Kraje 14: 470-505. Thomas, R. 1953. Sur deux formes critiques du genre Difflugia Leclerc. Bull. Soc. zool. Fr. 78: 132-136. 1954. Thecamoebiens de la region Bordelaise. Bull. Soc. Hist. nat. Toulouse 89 : 245-264. Vucetich, M. C. 1970. Algunos tecamebianos de la provincia de Formosa. Neotropica 16 : 42-48. 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. Manuscript accepted for publication 23 July 1982 British Museum (Natural History) An Atlas of Freshwater Testate Amoebae C. G. Ogden & R. H. Hedley 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, ecplogists, 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 G. Ogden Miscellanea A review of the Euplotidae (Hypotrichida, Ciliophora). By Colin Curds & Irene C. H. Wu The Opthalmotilapia assemblage of cichlid fishes reconsidered. By Peter Humphry Greenwood Osteology, genitalia and relationships of the Acanthodactylus (Reptilia: Lacertidae). By E. N. Arnold Morphological studies on some Difflugiidae from Yugoslavia (Rhizopoda, Protozoa). By Colin G. Ogden & Andjelija Zivkovic Printed by Henry Ling Ltd, Dorchester BOUND 2 0 JUL 1988