Bulletin of the British Museum (Natu BRITISH MUSEUM (NATURAL HISTORY) 3 1 AUG 1934 PRESENTED f+ ~ ~ "• t - ^IV ~^f A 'X ral History) Zoology series Vol 46 1984 T/\Al!f~lO^i4 • ' : 3 0 AUoj ^o-* I $ li \ • / (1 1 /• *'""-• :";."/ - " -V^"' British Museum (Natural History) London 1984 Dates of publication of the parts No 1 26 January 1984 No 2 23 February 1984 No 3 29 March 1984 No 4 31 May 1984 ISSN 0007-1 498 Printed in Great Britain by Henry Ling Ltd, at the Dorset Press, Dorchester, Dorset Contents Zoology Volume 46 No 1 A review of the Mastacembeloidei, a suborder of synbranchiform teleost fishes Part 1 : Anatomical descriptions By Robert A. Travers 1 No 2 A review of the spider subfamily Sparataeinae nom. n. (Araneae: Salticidae) with descriptions of six new genera By F. R. Wanless 135 No 3 The family Nannastacidae (Crustacea: Cumacea) from the deep Atlantic By N. S. Jones . . 207 No 4 Miscellanea On the foraminiferal genera Tritaxis Schubert and Trochammi- nella Cushman (Protozoa: Foraminiferida). By P. Bronnimann & J. E. Whittaker 291 A lectotype for Jadammina macrescens (Brady) and emendation of Jadammina Bartenstein & Brand (Protozoa: Foraminiferida). By P. Bronnimann & J. E. Whittaker 303 A neotype for Trochammina inflata (Montagu) (Protozoa: Forami- niferida) with notes on the wall structure. By P. Bronnimann & J. E. Whittaker .311 The Conchoecia reticulata species-group, with descriptions of C. reticulata Miiller (1906), C. caudata (1891), and two new species. By C. J. Ellis 317 The juvenile stages of eight swimming crab species (Crustacea: Brachyura: Portunidae); a comparative study. By R. W. Ingle & A. L. Rice .345 The freeliving marine nematode genus Sabatieria (Nematoda: Comesomatidae). II. Redescriptions of five European species. By H. M. Platt . 355 Bulletin of the British Museum (Natural History) review of the Mastacembeloidei, a suborder of synbranchiform teleost fishes Part I: Anatomical descriptions bert A. Travers Zoology series Vol 46 No 1 26 January 1984 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), 1984 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 ISBN 0 565 05000 1 ISSN 0007-1498 Zoology series Vol46No. 1 pp 1-133 British Museum (Natural History) Cromwell Road London SW7 5BD Issued 26 January 1984 A review of the Mastacembeloidei, a suborder of synbranchiform teleost fishes Part I: Anatomical descriptions Robert A. Travers Department of Zoology, British Museum (Natural History), Cromwell Road, London SW7 5BD1 Contents Synopsis Introduction Nomenclatural note Material and methods Material Methods Abbreviations Osteology of Mastacembelus mastacembelus . Neurocranium Jaws Hyopalatine arch Opercular series Hyoid and branchial arches Pectoral girdle Vertebral column Dorsal and anal fins Caudal fin Squamation ../.... Osteology of Chaudhuria caudata . Neurocranium Jaws Hyopalatine arch Opercular series Hyoid and branchial arches Pectoral girdle Vertebral column Dorsal and anal fins Caudal fin . , Squamation Osteology of Pillaia indica .... Neurocranium Jaws . Hyopalatine arch Opercular series Hyoid and branchial arches Pectoral girdle . . . . . Vertebral column 6 6 6 6 9 13 13 19 21 22 23 27 29 30 31 32 32 32 36 36 38 39 41 41 43 43 43 43 43 45 45 46 46 46 48 JThis research was carried out in the Department of Zoology, British Museum (Natural History) and was submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy in the Faculty of Science, University of London. The author's present address: Department of Anatomy & Cell Biology, St. Mary's Hospital Medical School, Norfolk Place, London W2 1PG. Bull. Br. Mm. not. Hist. (Zool.) 46 (1) : 1-133 Issued 26 January 1984 R. A. TRAVERS Dorsal and anal fins 48 Caudal fin . 48 Squamation 49 Comparative osteology of the Mastacembeloidei 49 Neurocranium 50 Jaws 76 Hyopalatine arch ..*......... 82 Opercular series 86 Hyoid arch 87 Branchial arches • ... 90 Pectoral girdle 98 Vertebral column "... 101 Dorsal and anal fins 1 09 Caudal fin Ill Squamation 115 Myology of Mastacembelus mastacembelus 117 Cephalic muscles 117 Group 1 : Adductor mandibulae 118 Levator arcus palatini 119 Dilatator operculi 119 Group 2: Levator operculi 119 Adductor operculi 119 Adductor hyomandibulae 120 Adductor arcus palatini 120 Others: 'Musculus intraoperculi' 120 Hyohyoidei adductores 121 Obliquus superioris 122 Baudelot's Ligament 122 Comparative myology of the Mastacembeloidei 122 Cephalic muscles 122 Group 1: Adductor mandibulae 123 Levator arcus palatini 125 Dilatator operculi 125 Group 2: Levator operculi 125 Adductor operculi 125 Adductor hyomandibulae 125 Adductor arcus palatini 126 Others: 'Musculus intraoperculi' 128 Hyohyoidei adductores 128 Obliquus superioris 128 Baudelot's Ligament 128 Acknowledgements 130 References 130 Synopsis The Mastacembeloidei or spiny eels (comprising the families Mastacembelidae, Chaudhuriidae and Pillaiidae) is a distinctive group of about 70 freshwater species with a tropical and subtropical Oriental and Ethiopian distribution, currently recognised as a suborder of the perciform fishes. The majority of its 70 species have been placed in a single genus, Mastacembelus, without regard to their genealogical relationships, and the sub-order as a whole has not been the subject of a detailed taxonomic or anatomical review. A revision of the genera and families within the suborder, and a reconsideration of its interrelationships within the Percomorpha, are the overall objectives of this study. The present work consists of anatomical descriptions of all available mastacembeloid species. The osteology of Mastacembelus mastacembelus, Chaudhuria caudata and Pillaia indica is described in detail, and is compared with that in the majority of described species. Myological studies are restricted to the cephalic region (jaw and opercular muscles only), and the arrangement in Mastacembelus mastacembelus is described and compared with that found in the other mastacembeloids examined. MASTACEMBELOIDEI I: ANATOMICAL 3 Introduction The Mastacembelidae, or spiny eels, a family of eel-like percomorph fishes is widely distri- buted in tropical and subtropical regions of Africa, SE. Asia and the Middle East (Ethiopian and Oriental zoogeographic regions). The eel-like appearance of mastacembelids is enhanced by lack of pelvic fins, a long body with numerous vertebrae, a tendency for the dorsal and anal fins to be confluent with the caudal fin, and a narrow, tapered cranium terminating in a pointed rostral appendage. Anterior to the rayed dorsal fin in almost all species is a long series of isolated spines. The present state of mastacembelid taxonomy is confused. No revision of the entire family has ever been undertaken. Since the first scientific description of this group (Russell, 1756; Gronovius, 1763 & Scopoli, 1777) numerous species have been described, most of which were placed in the genus Mastacembelus Scopoli, 1777. Exceptionally, one species, originally described by Bloch (1786, & see Sufi, 1956: 100) was placed in a separate genus, Macrognathus Lacepede, 1 800 (Bloch's Ophidium). The most recent synoptic review of Mastacembelus was published by Boulenger (1912) who recognised 14 Asian, 1 Middle Eastern and 30 African species. Since then, numerous descriptions of new species, particularly from Africa, have appeared in the literature (Table 1), and one was assigned to a new genus (Poll, 1958). However, the validity of this generic distinction was questioned by Roberts & Stewart (1976). Many unidentifiable African speci- mens lodged in the collections of major national museums including the British Museum (Natural History); Museum of Comparative Zoology, Harvard, and Koninklijk Museum Voor Midden- Afrika, Tervuren, justify the need for a revision of the African mastacembelids. The state of Oriental mastacembelid taxonomy is little better, although it has been the subject of a more recent revision (Sufi, 1956). Sufi (op. cit.) recognised 15 oriental Mastacembelus species and a single Macrognathus species on the basis of superficial anatomical and morphometric characters. Macrognathus remained monotypic until recently (Roberts, 1980). Evidence in support of splitting the single Macrognathus species into 3 taxa and expanding this genus to include other species is provided here. The interrelationships of the mastacembelids with other teleostean fishes have had no less a long and obscure history. Major general classifications treating the Mastacembelidae and their affinities are summarised in Table 2. Their appearance caused the early describers in the latter part of the eighteenth and early nineteenth century to associate them with the true eels (Anguilliformes). By the middle of the nineteenth century Giinther (1861) had noticed their many affinities to acanthopterygian fishes and considered them 'acanthopterous eels' distantly related to the Blenniidae. However, it was not until Boulenger (1904) that they were given separate subordinal status, as the Opisthomi, within the Teleostei. Following this, Regan (1912) elevated them to ordinal rank, although he could not trace their affinity to any particular group. Berg (1947: 494) followed Regan (op. cit.) in giving the mastacembelids separate ordinal status (Mastacembeliformes) within the teleosts, but Greenwood, Rosen, Weitzman & Myers (1966) in their phyletic study of teleostean fishes reduced the taxon to subordinal status and included the Mastacembeloidei as one of their 20 suborders in the order Perciformes. This arrangement, apart from slight changes, has remained to the present day. In addition to the Mastacembelidae, two monotypic families have been included in the suborder Mastacembeloidei. Annandale (1918) erected the family Chaudhuriidae to accom- modate a small eel- like fish collected from the Inle Lake, Burma (and recently also collected from Thailand; Roberts, 1980). He considered this small eel-like taxon to be a member of the true eels (Anguilliformes) but was unable to assign it to any known family, partly as a result of its distinct 'fan-shaped' caudal fin (Whitehouse, 1918). Regan (1919), considering the characters described for Chaudhuriidae, showed its affinity to mastacembelids rather than to true eels and placed it in the Mastacembeliformes (his Opisthomi). On the basis of this and new anatomical descriptions, Annandale & Hora (1923) followed his classification as did Mitra & Ghosh (193 1) on the basis of the soft anatomy. Berg (1947), however, considered 4 R. A. TRAVERS Table 1 African species assigned to the genus Mastacembelus (in chronological order of their description). Species Authority Date * Mastacembelus cryptacanthus Giinther 1867 Mastacembelus niger Sauvage 1878 Mastacembelus marchii Sauvage 1892 Mastacembelus marmoratus Perugia 1892 Mastacembelus tanganicae Giinther 1893 Mastacembelus ophidium Giinther 1893 Mastacembelus liberiensis Steindachner 1894 Mastacembelus loennbergii Lonnberg 1895 Mastacembelus congicus Boulenger 1896 Mastacembelus shiranus Giinther 1896 Mastacembelus flavomarginatus Boulenger 1898 Mastacembelus nigromarginatus Boulenger 1898 Mastacembelus moorii Boulenger 1898 Mastacembelus brachyrhinus Boulenger 1899 Mastacembelus ellipsifer Boulenger 1899 Mastacembelus paucispinis Boulenger 1899 Mastacembelus frenatus Boulenger 1901 Mastacembelus greshoffi Boulenger 1901 Mastacembelus goro Boulenger 1902 Mastacembelus sclateri Boulenger 1903 * Mastacembelus ansorgii Boulenger 1905 * 'Mastacembelus signatus Boulenger 1905 Mastacembelus cunningtoni Boulenger 1906 Mastacembelus longicauda Boulenger 1907 Mastacembelus batesii Boulenger 1911 Mastacembelus brevicauda Boulenger 1911 Mastacembelus reticulatus Boulenger 1911 * Mastacembelus trispinosus Steindachner 1911 Mastacembelus ubangensis Boulenger 1911 * Mastacembelus moeruensis Boulenger 1914 Mastacembelus stappersii Boulenger 1914 * Mastacembelus laticauda Ahl 1937 Mastacembelus albomaculatus Poll 1953 t Mastacembelus brichardi Poll 1958 Mastacembelus platysoma Poll & Matthes 1962 * Mastacembelus flavidus Matthes 1962 Mastacembelus micropectus Matthes 1962 Mastacembelus plagiostomus Matthes 1962 Mastacembelus zebratus Matthes 1962 * Mastacembelus sanagali Thys van den Audenaerde 1972 * Mastacembelus seiteri Thys van den Audenaerde 1972 Mastacembelus aviceps Roberts & Stewart 1976 Mastacembelus crassus Roberts & Stewart 1976 * Mastacembelus latens Roberts & Stewart 1976 Mastacembelus vanderwaali Skelton 1976 Mastacembelus sp. nov. Roberts & Travers (in prep.) "Unavailable for dissection ^Caecomastacembelus N.B. Mastacembelus taeniatus Boulenger, 1901 Mastacembelus victoriae Boulenger, 1903 Mastacembelus mellandi Boulenger, 1914 I Synonymised with M. frenatus (Matthes, 1962 and f Skelton, 1976) Mastacembelus mutombotomba Pellegrin 1936--' MASTACEMBELOIDEI I. ANATOMICAL Table 2 Proposed affinities of the Mastacembelidae. Authority Date Relationship Gronovius 1763 Apodes (Anguilliformes) Bloch 1786 Apodes (Anguilliformes) Linneaus 1758 Apodes (Anguilliformes) Lacepede 1800 Apodes (Anguilliformes) Schneider (Ed.) in Bloch 1801 Apodes (Anguilliformes) Cuvier & Valenciennes 1831 Notacanthidae Miiller 1844 Scombroidei Bleeker 1859 Alostoma & Notacanthus Gunther 1861 'Acanthopterous eels' (in the Blenniformes) Boulenger 1904 Blenniidae (given separate subordinal status: Opisthomi) Goodrich 1909 Blenniidae Regan 1912 Percomorphi (could not trace affinity to any particular group; given separate ordinal status: Opisthomi) Frost 1930 Percidae Job 1941 Nandidae Berg 1940 Acanthopterygii (given separate ordinal status as Mastacembeliformes) Berlin & Arambourg 1958 Acanthopterygii (given separate ordinal status as Mastacembeliformes) Bhargava 1953 & \963a Blennidae Freihofer 1963 Percoidei Greenwood et al 1966 Perciformes (given separate subordinal rank: Mastacembeloidei) McAllister 1968 Synbranchidae Gosline 1971 Synbranchidae Chaudhuriidae '. . . so specialised that it plainly deserves the rank of a special order' and assigned it to the Chaudhuriiformes. Sufi (1956) was inclined to agree with Berg (op. cit.), although Greenwood et al (1966) retained Chaudhuriidae in the mastacembeloids. Most recently, Yazdani (1972 & 1975) erected a new genus Pillaia for a small eel-like fish collected from the Kasi Hills, Meghalaya. Following more detailed anatomical descrip- tion and comparison with the Mastacembelidae and Chaudhuriidae, Yazdani (19760) con- cluded that this genus could be placed in the Mastacembeloidei and erected the Pillaiidae partly as a 'link' between the Mastacembelidae and Chaudhuriidae (Yazdani 1978) and also because of a number of anatomical specialisations including the presence of a single upper jaw element (Yazdani 19766). A second species of Pillaiidae (Talwar, Yazdani & Kundu, 1977) was described from two specimens collected from north east India. A taxonomic revision of the mastacembelid fishes requires a comprehensive study of their anatomy, particularly that of the African taxa, since existing descriptions, apart from those by Regan (1912: 217-219), Gregory (1933: 353-354), Sufi (1956: 95-96), Poll (1973: 221-230) and Taverne (1973 & 1980), are restricted mainly to accounts dealing with species from the Indian fauna. These include descriptions of cranial development and osteology (Bhargava, 19570 & 6, 1958 & 19630; Maheshwari, 1963 & 19650; Dalela, 1968; Dalela & Garg, 1968; and Yazdani, 19760 & 6), cephalic sensory canals (Maheshwari, 1971), myology (Dubale, 1952), the olfactory system (Bhargava, 19620 & b), nervous system (Maheshwari, 19656), vascular system (Saxena, 1956; Bhargava, 19636; Agrawal & Dalela, 1966a; Maheshwari, 19660; and Dalela, 19676), digestive system (Nagar & Khan, 1957; Agrawal & Tyagi, 1963; Agrawal & Dalela, 19666; and Sriwastwa, 1970), endocrine system 6 R. A. TRAVERS (Khanna & Gill, 1973), excretory system (Chandrasekhar, 1961; and Dalela, 1967a), repro- ductive system (Swarup, Srivastava & Das, 1971; and Maheshwari, 1966ft) and respiratory system (Datta Munshi, 1 964). This literature contains only scattered and incomplete accounts of the internal anatomy, there are no comprehensive osteological descriptions, and virtually no account of the myology exists. The Chaudhuriidae and Pillaiidae also lack detailed anatomical coverage, and the numer- ous errors perpetuated in the literature (e.g. Annandale, 1918; Whitehouse, 1918; Annandale & Hora, 1923; Yazdani, 1976a & 1978) and questionable hypothesis regarding their relation- ships, both taxonomic and phyletic, necessitate a thorough anatomical description of these taxa as well. This study, therefore, is devoted to detailed osteological descriptions of Mastacembelus mastacembelus (and a partial investigation of its cranial myology), Chaudhuria caudata and Pillaia indica. These descriptions will then form part of a comparative anatomical analysis (including osteology and relevant aspects of cranial myology) of all available mastacembeloid species to provide a basis for a phylogenetic analaysis of the taxa (see Part II; Travers, 1984). Nomenclature! note The taxonomic assignment of mastacembeloid species in current use is followed here. How- ever, the succeeding phylogenetic analysis dictates the reclassification of most of these species. Details of these taxonomic changes, including the characters that make them necessary, are given elsewhere (Part II; Travers, 1984). Material and methods Material The spirit collection, stained specimens and dry skeletons of mastacembeloids held at the British Museum (Natural History) together with several specimens presented as gifts, loans from other institutions and a personal collection from Lake Tanganyika, provided the material on which this study is based. The material examined is listed in full in Table 3, the species arranged alphabetically under their current generic names. All specimens are listed with their registered numbers, together with codes indicating the type of examination or preparation involved, (all are BM(NH) registered specimens unless otherwise indicated). A key to these codes is given in the list of abbreviations on p. 12. Methods Osteological studies involved the use of formalin fixed specimens cleared and double stained with Alizarin Red (for bone) and Alcian Blue (for cartilage) following the methods of Dingerkus and Uhler (1977). Myological studies, on the other hand, involved the use of for- malin fixed and alcohol preserved specimens. To maximise the usefulness of specimens, where alizarin/alcian transparencies were required, myological examination was performed prior to maceration. Analyses of vertebral structures, fin spines and rays was aided by the use of radiographs. A series of triple-stained transverse histological sections and double- stained longitudinal sections was prepared for more detailed analyses of internal structures. All specimens were examined with the aid of a Zeiss IVb zoom binocular microscope, fitted with a Schott fibre optic illuminator. Where necessary a substage illumination unit and a camera lucida drawing tube were employed. The osteological nomenclature is based upon that of Harrington (1955) and Patterson (1977) supplemented by reference to numerous other relevant studies including: Patterson & Rosen (1977) for the ethmoid region, Patterson (1975) for the braincase, Nelson (1969) MASTACEMBELOIDEI I: ANATOMICAL Table 3 List of Study Material. Species Reg. No. Preparation Oriental mastacembeloid taxa Genus: Mastacembelus Mastacembelus alboguttatus Mastacembelus armatus Mastacembelus caudiocellatus Mastacembelus circumcinctus Mastacembelus erythrotaenia Mastacembelus guentheri Mastacembelus keithi Mastacembelus maculatus Mastacembelus mastacembelus Mastacembelus oatesii Mastacembelus pancalus Mastacembelus sinensis Mastacembelus unicolor Mastacembelus zebrinus Genus: Macrognathus Macrognathus aculeatus Macrognathus aral Macrognathus siamensis 189 1.1 1.30: 135-1 38 (Types) 1978.3.2:306-7 1955.6.22:16-17 LACM 38 127-2 1891.11.30:134 1893.6.30: 130-1 32 (Types) 1980.10.10:274 1955.6.22:12 1980.10.10:274 Unreg Unreg 1865.7.17:18 1893.3.6:156-157 1912.7.20:27 1938. 12. 1:267 (Type) 1978.3.20:312-314 1970.9.3:543-552 1955.6.22:10-11 1970.9.3:534-552 1970.9.3:543-551 1978.3.20:315 1974.2.22:1799-1806 1892.9.1:25 1891.6.19:3 1955. 6. 25:4-6 (Types) 1975.11.21:8 1893.6.30:113-118 Unreg. 1889.2.1:3642-3 Unreg. 1935.10.18:71 1927.10.1:19 1888.3.23:60-2 (Types) 1895.5.31:13-14 (Types) IHW-h Gift 1978.3.20:317 1955.6.22:24 1978.3.20:318 IHW-h Gift MCZ 9027 1891.11.30:115-124 Unreg. 1883.11.28:15 1889.11.12:52 1922.5.19:115 1889.2.1:3622-5 1858.8.15:51-3 1872.4.7:38 Unreg. Unreg. 1898.4.2:127-8 AP A/A MD MD DS R A/A MD R A/A R MD R R R A/A A/A A A MD R A/A, MD & R DS R R R A/A R A/A A/A MD A/A R R R A/A R R R A/A A/A & DS A/A MD MD MD&R A/A R R A/A MD R g Table 3 Continued. R. A. TRAVERS Species Reg. No. Preparation Oriental mastacembeloid taxa Genus: Chaudhuria Chaudhuria caudata Genus: Pillaia Pillaia indica Pillaia khajuriai African mastacembeloid taxa Genus: Mastacembelus Mastacembelus albomaculatus Mastacembelus ansorgii Mastacembelus aviceps Mastacembelus batesii »> »» Mastacembelus brachyrhinus Mastacembelus brevicauda Mastacembelus brichardi Mastacembelus congicus Mastacembelus crassus Mastacembelus cryptacanthus Mastacembelus cunningtoni Mastacembelus ellipsifer Mastacembelus flavidus »» ?> Mastacembelus flavomarginatus Mastacembelus frenatus Mastacembelus Mastacembelus Mastacembelus Mastacembelus „ (mellandi) „ (taeniatus) goro greshqffi liberiensis loennbergii Mastacembelus longicauda Mastacembelus Mastacembelus Mastacembelus marchii marmoratus micropectus Mastacembelus moorii MCZ 47058 1923.3. 10: 1-3 (Types) ZSI F10822/1 ZSI (9 ex.) ZSIFF816(Paratype) Pers. coll. MCZ 492 12 Unreg. 1905. 5.29:59 (Type) MCZ 50565 1912.6.29:10-16 1907.5.22:246 MCZ 50563 1904.7.1:250 1906.5.28: 193-1 96 (Types) 1976.5.21:99-108 MCZ 50255 1975.6.20:696-697 1901.12.26:64 1899.6.28:23 MCZ 50258 1866.6.26:11 (Type) Unreg. Pers. coll. RG 130435^39 1906.9.8:273 (Type) 1912.4.1:575-579 1961.12.1:356-7 1977.6.9:134-6 RG79-01-P-6335-339 RG91437 1937.4.16:18-22 1958.9.8:287 Unreg. RG73.10.P-7363-372 1969.3.26:68-69 1904.1.20:71 Unreg. 1910.2.23:7-10 1908.5.20: 189 (Type) MCZ 50590 RG 118712-719 MCZ 492 10 RG 130804-812 1955.12.20:1685 MCZ 50838 A/A & AP A& AP A/A A/ A, A, MD, R & AP AP A/A A/A R R A/A A/A & MD DS A/A A/A R A/A & MD A/A A/A MD DS A/A R A&R A/A & MD R R A/A & MD A/A A/A A/A A/A A/A A/A R A/A A/A R HS A/A & MD R A/A A/A A/A A/A A/A A/A MASTACEMBELOIDEI I: ANATOMICAL Table 3 Continued. Species Reg. No. Preparation African mastacembeloid taxa Mastacembelus niger 137360-365 A/A Mastacembelus nigromarginatus 1969.4.28:11-12 A/A Mastacembelus ophidium 1968.123.30:4 A/A ,•> » 1936.6.15:1753-6 A/A Mastacembelus paucispinis 1976.5.21:119-129 A/A ,, ,, RG 178099 A Mastacembelus plagiostomus Pers. coll A/A Mastacembelus platysoma RG 78-25-P.34-38 A/A Mastacembelus reticulatus 1932.5.18:105-6 A/A » Unreg. R Mastacembelus sclateri 904.7.1:104-105 A/A „ 1911.5.30:35 DS ») » 1909.4.29:111 R 5? 55 1911.5.30:38 R Mastacembelus shiranus Unreg. A/A 55 55 1969.2.20:3-12 A/A Mastacembelus signatus 1905. 11. 10: 13 (Type) R Mastacembelus stappersii RG 152167 A Mastacembelus tanganicae Pers. coll. A/A 5J 1968.12.30:2-3 A/A „ MCZ 49209 A/A Mastacembelus ubangensis RG 124267-268 A/A Mastacembelus vanderwaali 1977.2.3:168-172 A/A 55 55 AM 3450 A Mastacembelus zebratus MCZ 492 11 A/A 55 55 RG 130800-801 R Mastacembelus sp. nov. CAS Gift A/A for the branchial arches, and Greenwood & Rosen (1971) and Rosen (1973) for the caudal skeleton. The nomenclature of muscles follows that of Winterbottom (1974), and cranial nerves that of Freihofer (1978). Abbreviations Abbreviations used in text figures and tables. Skeletal elements Aa AAPP ACh ADPt APR AHS AP AP + MPt AS ASPt Bb 1-4 Bblk BblkC Bb2VP Bb2VPA Anguloarticular Adductor arcus palatini process Anterior ceratohyal Anal fin distal pterygiophore Anal fin ray Autogenous haemal spine Anterior process Anal proximal and medial pterygiophores Anal spine Anal spine supporting pterygiophore Basibranchial 1 to 4 Basibranchial 1 keel Basibranchial 1 keel with cartilaginous ventral edge Basibranchial 2 ventral process Basibranchial 2 ventral process arched 10 Bh BLF Bo Bpt BR Bs C Cb 1-5 Cb5MP Cb5Tp Ck Cmen CMF CN Com Cor CVt 1 D DCP DDPt DFR DHh DP DP+MPt DPP DPt DS DSP DSPt E 1-3 Eb 1-4 EC EcR Ect End EndAP ENS Ep EpR Ex ExDP Exsc ExVE F FDL FF Fn FP FPb2 FPmAS FTp GTS H 1-6 HAF Hb 1-3 Hb3AP Hb3Tp HHAVt(l) HP R. A. TRAVERS Basihyal Baudelot's ligament fossa Basioccipital Basipterygia Branchiostegal ray Basisphenoid Cleithrum Ceratobranchial 1 to 5 Ceratobranchial 5 muscular process Ceratobranchial 5 toothplate Cleithrum keel Cartilage meniscus Cancellous medial face of lateral ethmoid Cartilage nubbin Coronomeckelian Coracoid 1 st Caudal vertebra Dentary Dentary coronoid process Dorsal fin distal pterygiophore Dorsal fin ray Dorsal hypohyal Dorsal process Dorsal proximal and medial pterygiophore Dentary posterior process Distal pterygiophore Dorsal spine Dentary symphysial process Dorsal spine supporting pterygiophore Epural 1 to 3 Epibranchial 1 to 4 Ethmoid cartilage Epicentral rib Ectopterygoid Endopterygoid Endopterygoid anterior process Expanded (anteroposteriorly) neuraj spine Epioccipital Epipleural rib Exoccipital Exoccipital dorsal perforations Extrascapula Exoccipital ventral extension Frontal Frontal descending lamina Facial foramen Fenestra Frontal pedicel Fragmented pharyngobranchial 2 Fragmented premaxilla alveolar surface Fused toothplate Gutter in lateral ethmoid for truncus supraorbitalis Hypural 1 to 6 Hyoid artery foramen Hypobranchial 1 to 3 Hypobranchial 3 anterior (descending) process Hypobranchial 3 toothplate Hemispherical head of 1st abdominal vertebra Hypural plate MASTACEMBELOIDEI I: ANATOMICAL HS Haemal spine Hyo Hyomandibula HyoAF Hyomandibular anterior flange HyoS Hyomandibular spur ICF Internal carotid foramen Ih Interhyal InP Interdigitating process lo 1-6 Infraorbital 1-6 loAP Infraorbital 1 anterior process loPP Infraorbital 1 posterior process LC Lateral commissure LCF Lateral commissure flange LE Lateral ethmoid LEVF Lateral ethmoid ventral facet LEVP Lateral ethmoid ventral process LP Lateral parapophysis MC Meckel's cartilage Met Metapterygoid MX Maxilla N Nasal NA Neural arch NAF Neural arch foramen NS Neural spine Op Operculum OPM Opening for the posterior myodome P Parasphenoid Pal Palatine PaLS Palatine spur PalSF Palatine suborbital flange PalT Palatine teeth Par Parietal Pb 2-4 Pharyngobranchial 2 to 4 PCh Posterior ceratohyal PCR Principal caudal fin rays PFR Pectoral fin rays Ph Parhypural Pm Premaxilla PmAP Premaxilla ascending process Pop Preoperculum Poz Postzygapophysis PP Postorbital process PPP Parasphenoid posterior process Pr Prootic PR Pleural rib PrAP Prootic anterior process Prorb S Preorbital spine PrS Prootic spur PrSh Prootic shelf Prz Prezygapophysis Pt Pterosphenoid PtN Pterosphenoid notch PtP Pterosphenoid pedicel PtT Posttemporal tubule Pu 2 & 3 Preural centra 2 to 3 Pu + U Fused ural and 1st preural centra Q Quadrate R 1-4 Radials (actinosts) 1-4 Ra Retroarticular ROSFF Ramus opercularis superficialis facialis foramen 11 12 R. A. TRAVERS SB Saccular bulla Sc Scapula ScaF Scapular foramen Snl Supraneural lamina So Supraoccipital SoC Supraoccipital commissure Sop Suboperculum SorC Supraorbital sensory canal commissure Sph Sphenotic SphAF Sphenotic anterior flange StSC Supratemporal sensory canal Sue Supraethmoid Sym Symplectic TF Trigeminal foramen TFF Trigeminal and facial foramen confluent TP4 Toothplate 4 TPOlfT Tubular passage for olfactory tract U 1-2 Uroneural 1 to 2 Uh Urohyal UhAP Urohyal ascending process UhF Urohyal facet Unc Uncinate process UTp Unfused toothplate V Vomer VCPH Vascular canal in head of parhypural VHh Ventral hypohyal Muscles and soft tissues AI, A2, A3 & Aw Parts of the adductor mandibulae A2a & A2p Deep and superficial subdivisions, respectively, of part A2 of the adductor mandibulae AAP Adductor arcus palatini AwApo Tendinous aponeurosis of part Aw of the adductor mandibulae A Hyo Adductor hyomandibulae AO Adductor operculi B Lig Baudelot's ligament DO Dilatator operculi Epax Epaxialis musculature Hyo Abd Hyohyoidei abductores Hyo Add Hyohyoidei adductores Int 'Musculus intraoperculi' LAP Levator arcus palatini LO Levator operculi MmLig Maxillo-mandibular ligament ObSup Obliquus superioris Olft Nervus olfactorius Pseu Pseudobranch RMT Ramus mandibularis trigeminus tAi, tA2a, tA2p, Tendons from parts of the adductor mandibulae tA3 & tAw TI Truncus infraorbitalis Note on the figures: even stipple-dots indicate the presence of cartilage. The scale on all figures indicates 1 mm. Table of study material A/A Double alizarin red/alcian blue stained transparency A Alizarin stained transparency HS Histologically stained and sectioned MD Muscle dissection (cheek and opercular region) MAST ACEMBELOIDEI I: ANATOMICAL 13 DS Dry skeleton preparation R Radiograph AP Alcohol preserved specimen not available for dissection or preparation (superficial gross morphology examined only) Unreg. Unregistered specimen held at BM (NH) Pers. coll. Personally collected specimen held at BM(NH) Institutional abbreviations AM Albany Museum, Grahamstown BM(NH) British Museum (Natural History) CAS California Academy of Sciences IHW-h Institute of Hydrobiology, Wuhan (China) LACM Natural History Museum of Los Angeles County MCZ Museum of Comparative Zoology, Harvard RG Koninklijk Museum voor Midden-Afrika, Tervuren ZSI Zoological Survey of India Osteology of Mastacembelus mastacembelus Although Mastacembelus mastacembelus (Banks & Solander, in Russell, 1794) is the type species of the genus (Wheeler 1956) it has not been subjected to a detailed anatomical study. This description is based on two double stained specimens (standard length 2 1 2 mm. and 217 mm.) and a single skeletal preparation (see Table 3). Neurocranium Ethmovomerine region Of the two median endochondral ethmoid bones identified by Patterson & Rosen (1977) only the supraethmoid is present in M. mastacembelus. The supraethmoid is a laterally com- pressed bone that caps the anterodorsal part of the ethmoid region (Fig. 1 a). It consists of two regions; anteriorly, a thin median septum separates the olfactory sacs and posteriorly a long posterodorsally directed process lies between the anteromedial face of each frontal. The anteroventral edge of the median septum is fused to the vomer, and the anterodorsal edge is enlarged to form an ovoid prominance for the attachment of ligaments which help govern the movement of the rostral appendage. Below the posterodorsal process the lower corner of the supraethmoid is cartilaginous and extends as a septal cartilage along the anterodorsal surface of the parasphenoid (below the lateral ethmoids) into the orbital cavity (Fig. la). The vomer is a long bone and consists of a broad faceted head region and a long posterior shaft (Fig. la & b). Both the anterior and anterolateral faces of the vomerine head are faceted; they articulate with the rostral appendage and medial face of the short ascending process from the premaxilla, respectively. The vomerine shaft lies in a groove on the underside of the parasphenoid and extends posteriorly to a point adjacent to the anterior edge of the pterosphenoid. The dorsal surface, posterior to the median supraethmoid septum, contacts the ventral surface of the posterior cartilaginous region of the supraethmoid. Vomerine teeth are absent. Each Lateral ethmoid is connected to its partner in the midline, and together they saddle the cartilaginous region of the supraethmoid. There is no anterior myodome between the lateral ethmoids. The medial wall is compressed into a cancellous bony sheet that contacts its partner in the midline anterodorsal to the cartilaginous end of the supraethmoid. This wall, together with the outwardly convex lateral wall gives the lateral ethmoid a tubular cen- tral region (Fig. 2). The olfactory sac is hypertrophied and its posterior end lies within the anterior entrance to this tubular centre of the lateral ethmoid. The posterior opening accom- modates the broad nervus olfactorius (Freihofer, 1978), which runs directly from the olfactory bulb to the nasal organ. 14 R. A. TRAVERS The dorsal edge of the lateral ethmoid consists of an anterior arm which lies below the posteroventral surface of the nasal, and a posterior arm that lies below the anteroventral surface of the frontal. A gutter runs longitudinally along the dorsomedial face and carries part of the truncus supraorbitalis nerve prior to its separation into two main rami. A large rounded condyle on the lateral face of the lateral ethmoid articulates syndesmotically with the posterior ascending process on the 1st infraorbital bone. Ventral to this condyle is a facet which articulates synchrondrally with the anterior end of the suspensorium (the anterodorsal edge of the ectopterygoid and anterior tip of the endopterygoid). The nasal is a large, thin, flattened bone inclined to the vertical, and overlies the long olfactory cavity (Fig. la & c). The medial edge is joined by connective tissue to the dorso- lateral margin of the supraethmoid. Posteriorly, it overlaps the anterodorsal process of the lateral ethmoid and contributes, with the 1st infraorbital, to the rim of the posterior nostril. The dorsolateral margin of the 1st infraorbital is overlapped by the lateral edge of the nasal, and the two are joined by connective tissue. The nasal encloses the anterior region of the supraorbital sensory canal which forks anteriorly, the short lower arm terminating in a pore on its anterolateral surface. Orbital region The pterosphenoid is a major contributor to the long, precommissural lateral wall of the braincase. Its anterior edge contributes to the posterior rim of the orbital cavity and partly surrounds the optic foramen (Fig. la & b). The anterodorsal edge of the lateral wall is grooved, and accommodates the ventral edge of the frontal descending lamina. Posteriorly, the dorsal margin of the pterosphenoid is partly overlapped by the posterior margin of the frontal lamina and the anterolateral flange of the sphenotic. The ventral edge of the pterosphenoid is curved medially and sutured to its partner in the midline. Together, these bones form the ventral rim of the optic foramen and roof the small posterior myodome, giving this region of the neurocranium a somewhat tubular shape. The posterior edge of the pterosphenoid lies between the sphenotic and prootic, and con- tributes to the rim of the trigeminal foramen. The lateral face of the pterosphenoid is overlain by a long anterior process on the prootic. Dorsal to this process the pterosphenoid is grooved longitudinally to accommodate the nerves issuing from the trigeminal foramen. The basisphenoid, the smallest bone in the neurocranial complex is depressed and Y-shaped. Its small size is the result of its compression between the ventral face of the median pterosphenoid symphsis and the dorsal surface of the parasphenoid (Fig. la). The tip of each dorsal arm of the basisphenoid contacts a pterosphenoid. A short ventral shaft extends down- wards towards the parasphenoid as a thin process dividing the posterior myodome. The parasphenoid is the longest bone in the neurocranium and extends from below the lateral ethmoids to the posterior edge of the basicranium (Fig. la & b). It consists of two main regions: a long anterior process bridging the orbital cavity (between the otic and nasal areas) and a longitudinal, trough-like, posterior region. The ventral surface of the anterior region is grooved to accomodate the vomerine shaft. A dorsal median ridge on the anterior part of the parasphenoid meets the membranous interorbital septum. The lateral wall of the posterior trough- like region overlaps the ventro lateral margin of the prootic; it is not developed into an ascending process. A notch in the dorsal edge of the parasphenoid (ventral to the lateral commissure in the prootic) forms, with the ventral edge of the prootic, the internal carotid foramen. The posteroventral face of the parasphenoid divides into a pair of processes which lie longitudinally on either side of a basioccipital ridge and extend to the posterior margin of that bone. The infraorbital series consist of one large element-the 1st infraorbital (lachrymal)-and 5 small tubules (2nd to 6th infraorbitals). The infraorbital sensory canal is enclosed within these elements (Fig. 3). The 1st infraorbital is expanded posteriorly and tapered anteriorly, extending to the tip of the nasal. Two large pores are present, as well as several irregular branches of the infra- orbital sensory canal system which terminate in small pores on the lateral face of the bone. MASTACEMBELOIDEI I: ANATOMICAL FDL Pt Sph So Par StSC 15 SorC Pal EC TF FF SB Sue B Pal PalS Ep Dpto Ex Bo Fig. 1 Mastacembelus mastacembelus, neurocranium in: (a) lateral view of left side; (b) ventral view and (c) dorsal view. The posterodorsal edge of this bone is developed into two ascending processes. The dorso- medial face of the larger posterior process is faceted and joined syndesmotically with the rounded condyle on the lateral ethmoid. A small lip on the anterior edge of the ascending process also contacts the lateral ethmoid. The smaller ascending process is joined by epider- mal tissue to the posteroventral edge of the nasal; together with the larger process it forms the ventral rim of the posterior nasal opening. 16 GTS PP CMR TPOtf.T Fig. 2 Mastacembelus mastacembelus, right lateral ethmoid in posteromedial view. lo2-6 AP ProrbS Fig. 3 Infraorbital series of Mastacembelus mastacembelus. The ventral edge of the bone tapers posteriorly to a distinct, pointed process (preorbital spine; Fig. 3), which pierces the integument ventral to the 2nd infraorbital tubule. The remaining infraorbital bones are reduced to ossifications around the sensory canal. The 2nd element partly overlaps the posterolateral face of the 1st, and has a single large pore midway along its length. The sensory canal portions of the 4th, 5th and 6th infraorbitals are decreasingly ossified. Otic region The prootic is the largest endochondral bone enclosing the cranial cavity, and in addition to its main posterior region has a prominent anterior process extending into the orbit (Fig. la&b). MASTACEMBELOIDEI I: ANATOMICAL 1 7 This region of the prootic overlaps the dorsolateral margin of the parasphenoid and in so doing obscures the basisphenoid laterally. A fossa in the dorsolateral margin of the prootic combines with a similar one in the ventrolateral margin of the sphenotic to form the socket for the anterior hyomandibular condyle. Posterior to the socket, the prootic is bevelled posteroventrally and is connnected dorsally to the pterotic by a number of dentate sutures; ventrally it is connected to the anterolateral edge of the exoccipital and the anterodorsal edge of the basioccipital. The posterolateral face of the bone is bullate and accommodates the small sacculus in its entirety. The trigeminofacialis chamber is situated anterior to the saccular bulla. The large trigeminal foramen lies anterior to the slender lateral commissure (Fig. 1 a), whilst the facial foramen, which is small (relative to the size of the trigeminal foramen), generally pierces the prootic medial to the lateral commissure. The trigeminal foramen is bounded by the sphenotic (dorsally) and the prootic (ventrally). A short descending spur from the ventral edge of the sphenotic lies above the tip of a similar spur rising from the dorsal edge of the prootic. These spurs do not contact one another; together with the posterior edge of the pterosphenoid they form the rim of the trigeminal foramen. Medial to the trigeminofacialis chamber the prootic bears a vertical strut pierced by the inner opening of the facial foramen. Dorsally, this medial strut contacts the sphenotic, and ventrally it meets its partner in the midline. A hollow, gutter-like channel longitudinally indents the ventromedial face of the strut. The internal carotid artery runs along this channel from the small, posterior myodome and leaves through a foramen situated along the prootic/ parasphenoid junction, ventral to the lateral commissure. A narrow, longitudinal ridge on the anterolateral face of the prootic is continuous with the lower edge of a groove in the ventrolateral face of the pterosphenoid, and supports the truncus infraorbitalis. The large sphenotic is a major element in the dorsolateral wall of the braincase (Fig. la & b). It is characterised by a prominent, anterolateral flange which overlies its medial, sutured, connection to the pterosphenoid. Anterolaterally, the sphenotic contacts the frontal descending lamina by which it is excluded from contributing to the orbital border. Dorsally the sphenotic is grooved and accommodates the ventrolateral edge of the frontal. The posterolateral edge of this groove forms the postorbital process (dorsal to the lateral commis- sure), from which the dilatator operculi muscle originates. The posterior position of this postorbital process (relative to the orbit) illustrates the extreme attenuation of the pre- commissural region of the neurocranium. The posterior and posterodorsal edge of the sphenotic is overlapped by the prootic. A wide dorsomedial flange extends below the ptero- tic, to contact the ventral surface of the parietal. Below its postorbital process the sphenotic is sutured to the dorsal surface of the lateral commissure and anterior to this forms the upper border of the trigeminal foramen. The medial face of the sphenotic accommodates the anterior semicircular canal which is looped through the bone, forming the pons moultoni. The pterotic consists of two portions; the ventral autopterotic and the dorsal dermopterotic (Fig. 1 a & c). The autopterotic is connected to the sphenotic anteriorly, the prootic ventrally, with the exoccipital and epioccipital posteriorly. The dorsal edge of this region is fused to the ventral edge of the dermal portion of the pterotic. The main body of the pterotic encloses the horizontal semicircular canal, and as a result its lateral face is bullate; its ventral surface is grooved to accommodate the posterior hyomandibular head. There is no posttemporal fossa although the ventral margin of the pterotic forms part of a recess in the lateral wall of the basicranium. The dermopterotic extends anteriorly between the sphenotic and frontal. Its anterior tip and posterodorsal edge are sutured to the lateral edge of the parietal. The temporal junction between the supraorbital, preopercular and posttemporal sensory canals is contained in the dermopterotic. The epioccipital is small and forms, with the exoccipital and supraoccipital, the postero- dorsal wall of the basicranium (Fig. la & c). Dorsally, it is overlapped by the posterior edge of the parietal. An artery which supplies 18 R. A. TRAVERS the epaxialis musculature leaves the cranial cavity via a small foramen midway along the parietal/epioccipital border. Ventrally, the epioccipital is bounded largely by the exoccipital, to which it is sutured, and partly by the pterotic. The inner aspect of the epioccipital contains the posterior semicircular canal and this imparts a bullate appearance to the bone's posteroventral face. The dorsal surface of this bulla forms the floor of a shallow fossa on the posterior face of the epioccipital (lateral to the posterodorsal foramen). A large, partly ossified tendon from the epaxial musculature inserts in this fossa. Each exoccipital is an irregularly shaped bone and is a major contributor to the posterior wall of the neurocranium (Fig. la). Above the foramen magnum a dorsomedially directed process is connected in the midline to its partner by a pair of dentate processes. This symphy- sis, combined with a ventromedial one, results in the exoccipitals completely surrounding the foramen magnum. The complex anterior edge of the exoccipital connects, by thin interdigitating sheets of bone, with the epioccipital dorsally, the pterotic laterally, and the prootic ventrally. The junction between these elements lies within the recess in the lateral wall of the basicranium (from which originate the branchial levator muscles). The ventral surface of each exoccipital is flat and abuts against the dorsolateral surface of the basioccipital. Posteroventrally, they have prominent, concave, deltoid facets. These facets, in combination with a similar shaped facet on the posterior face of the basioccipital, form the occipital facet (a concave socket) which articulates with the 1 st abdominal vertebra. The inflated appearance of the anterolateral wall is a result of an inner recess in the exoccipital. Three major foramina perforate the exoccipital. The small glossopharyngeal foramen pierces the bullate anterolateral wall, a large subdivided foramen, for branches of the occipito-spinal nerve, lies posterior to that for the glossopharyngeal nerve, whilst between, and slightly dorsal to them, lies the vagal foramen. The stout basioccipital is approximately rectangular in outline (Fig. Ib). Its dorsal surface is pyramidal, with the four raised faces converging dorsally to form a longitudinal ridge. The anterodorsal face is excavated to form a pair of pit-like fossae, the cavum utriculae. The faceted and concave posterodorsal face contributes to the tripartite occipital facet (see above). The ventral surface of the basioccipital is flat except for a low, central, longitudinal ridge which separates the posterior processes of the parasphenoid. The posterior myodome is small in comparison with that in other perciforms. It is roofed by the medial process of the pterosphenoids and divided in the midline by the ventral shaft of the basisphenoid. The supraoccipital is a flattened bone and may be divided topographically into two re- gions: (1) the anterior horizontal part and (2) the sloped posterior region which is inclined at 45° to the former (Fig. Ic). A supraoccipital crest is absent. The dorsal surface is transversely convex and bounded on either side by the parietals and by a posterior portion of the frontals. All these surrounding bones cover the supraoccipital margin. Crossing its posterior surface is a gutter-like channel which accommodates the supratemporal sensory canal commissure. The posterior portion of the supraoccipital is bordered laterally by the epi- and exoccipitals. Ventrally, its tip meets the exoccipital dorsal symphysis by which it is excluded from the foramen magnum. The frontal is the major roofing bone of the cranium and is comprised of two regions: dorsally a flat, horizontal roofing region and ventrally a descending vertical lamina (Fig. la &c). The dorsal region of the frontal is particularly attenuated and narrows above the orbit. Its flat surface lacks crests or any form of sculpturing. Anteriorly, it overlies the posterior tip of the ventral ethmoid, and posteriorly it overlaps the anterior margin of the supra- occipital. Beneath the anterior end of the frontal, and joined to it by connective tissue, is the posterodorsal arm of the lateral ethmoid (see above). The posterior end of the dorsal region of the frontal, overlaps a wide bony lip on the anterior edge of the parietal and con- MASTACEMBELOIDEI I: ANATOMICAL 19 nects posterolaterally with the dorsal edge of the pterotic and the sphenotic. The lateral edge of the frontal curves ventrally and is concave above the orbit. Medially, the frontals meet along a straight suture. The frontal sensory canal (supraorbital branch of cephalic system) passes along the lateral margin of the bone. Posterior to the orbit the ascending infraorbital canal connects with the supraorbital canal, its junction indicated by a large pore in the lateral edge of the frontal. Anterior to this point the supraorbital canal opens through a medial pore which marks an anterior commissure between the canals from either side of the neurocranium (Fig. Ic). The frontal descending lamina contributes to the postorbital lateral wall of the braincase (Fig. la). Its anterior edge forms, with the pterosphenoid, the posterior rim of the orbit. The ventral lamina, together with the dorsal region of the frontal and the pterosphenoids enclose the optic foramen. The ventral edge of the lamina overlaps the lateral face of the pterosphenoid, and posteriorly is sutured to the anterolateral edge of the sphenotic. The parietal is approximately square in outline except for a short posterolateral arm (Fig. la & c). Anteriorly, a wide bony lip is overlapped by the frontal; posteriorly it is sutured to the dorsal edge of the epioccipital. Laterally, the parietal is joined to the pterotic and posterodorsal flange of the sphenotic, whilst medially it contacts the supraoccipital. The unsculptured dorsal surface of the parietal is flat except for a slight curvature of its ventrolateral aspect. A sensory canal (supratemporal branch) crosses within the posterodor- sal margin, from its lateral (pterotic/posttemporal) to its medial (commissure) connections. A single, large pore on this canal pierces the posterodorsal surface of the parietal. Extrascapular bones are absent. Two small ossified dermal tubules lie equally spaced along the postcranial sensory canal between the tip of the posterolateral arm of the parietal and the dorsal tip of the supraclieth- rum. These tubules represent the only ossified remnants of the posttemporal bone (Fig. 1 1). Jaws Upper Jaw The premaxilla is a weakly curved, rod-like element, characterised by its short ascending process (Fig. 4). The bone's dorsal edge is tightly joined to the ventral face of the maxilla MX Io2 Com Ra DSP DPP Fig. 4 Mastacembelus mastacembelus, lateral view of left upper and lower jaw bones with 1 st and 2nd infraorbitals. 20 R. A. TRAVERS by a broad sheet of connective tissue. Anteriorly, each premaxilla curves medially (below and beyond the anterior end of the maxilla) to form a midline symphysis. The short stump-like ascending process articulates (via a facet on its medial face) with the faceted anterolateral end of the vomer. The premaxillae are not protrusible. Its posteroventral end is laterally compressed and partly overlaps the ventral flange of the maxilla. The tooth-bearing alveolar surface of the premaxilla is broadest anteriorly and tapers posteriorly. The dentition is in the form of large, acrodont, caniniform teeth with pos- teriorly directed tips. Tooth attachment (to the premaxilla, dentary and pharyngeal bones) is by a ring of collagen between the tooth base and bone, in a mode equivalent to type 2 described by Fink (1981). The teeth are arranged in 1-8 irregular rows (depending upon the position along the premaxilla) and decrease in size medially. The maxilla tapers anteriorly to a blunt tip which is connected, via a short ligament, to the posterior edge of the premaxillary ascending process and medially to the lateral facet on the head of the vomer. Posteriorly, the maxilla is thickened and expanded ventrolaterally to form an extension which, when the jaws are adducted, overlies the lateral face of the cor- onoid process (Fig. 4). This wide posterior region of the maxilla is joined to the coronoid process by a medial sheet of connective tissue. The dorsal edge is loosely joined by epidermal tissue to the ventromedial margin of the 1 st infraorbital, and the ventral edge is connected firmly to the dorsal edge of the premaxilla. Lower Jaw The dentary is a long bone and although straight is directed mesad. Its symphysis lies pos- terior to the median connection of the premaxilla and there is a low symphysial projection on its anteroventral edge. The dentary divides, posterolaterally, into an upper coronoid and a lower ventral arm. The coronoid region is developed posteriorly into a relatively tall, shallow coronoid process (Fig. 4). The long and narrow dorsal surface anterior to the coronoid process is alveolate and toothbearing. This toothed surface contains 3 rows of caniniform acrodont teeth, those of the outer row being somewhat larger than the inner teeth. The alveolar surface narrows posteriorly and does not extend onto the coronoid process. The dentary portion of the mandibular sensory canal opens to the surface of the bone through four pores. The posteroventral region of the dentary extends below and beyond the point at which the sensory canal enters the dentary. The dorsal surface of this posteroventral projection (Fig. 4) is grooved and accommodates the ventral edge of the anguloarticular and the anteroventral edge of the retroarticular. The ventral edge of the lower jaw is, therefore, almost entirely formed by the dentary. The long anguloarticular (Fig. 4) is characterised by two unusual features: the presence of a straight dorsal edge with no ascending process, and by the size and dorsal position of the coronomeckelian. The anterior end of the anguloarticular lies between the coronoid and the ventral limb of the dentary. The posterodorsal edge is capped by a wide, transverse facet that receives the anterior condyle of the quadrate in a euarthroidal joint. On the posteromedial face of the anguloarticular is a small rounded ridge (ectosteal plate). Meckel's cartilage lies between the anterior end of this ridge and the dentary. The retroarticular is a small L-shaped bone connected to the posteromedial face of the anguloarticular. It lies below the dorsal facet on the anguloarticular to which it is connected synchondrally. The coronomeckelian (sesamoid articular) is particularly large and uniquely positioned (Fig. 4) in comparison with its size and position in other teleostean fishes. It is long, narrow and tapers at both anterior and posterior ends. The anterior end overlaps the dorsomedial margin of the anguloarticular and is connected to its medial face, dorsal to Meckel's cartilage. From this point the coronomeckelian extends posterodorsally across the anterolateral face of the suspensorium. The posterior end lies lateral to the junction of MAST ACEMBELOIDEI I: ANATOMICAL 21 the ectopterygoid with the quadrate. The anteroventral tendon of part A3 of the adductor mandibulae muscle inserts on to the posterior end of the coronomeckelian and the ramus mandibularis trigeminus (part of the Vth cranial nerve) passes downwards, along its ventral edge (Fig. 4), to extend anteriorly into the dentary. Hyopalatine arch The stout hyomandibula has its dorsal surface produced into two articular heads separated by a shallow depression (Fig. 5). The anterior condyle has a synchondral articulation (via a cartilaginous meniscus) with the anterior, prootic-sphenotic fossa on the lateral wall of the neurocranium. The larger, posterior condyle is ellipsoidal and fits into the channel-like pterotic fossa with which it articulates synchondrally. The ventral part of the hyomandibula is a broad shaft; its tip is cartilage-capped and joined syndesmotically with the posterior end of the symplectic. The anterior edge of this shaft bears a small descending spur (Fig. 5). The truncus hyomandibularis (principally composed of fibres from the Vllth cranial nerve) enters the hyomandibula through a dorsomedial foramen and passes down through its shaft to emerge from a ventrolateral foramen. The posterior edge of the shaft is deeply grooved and accommodates the upper arm of the preoperculum. Dorsal to this groove the posterior edge is produced into a rounded con- dyle which articulates synchondrally with the operculum. A shallow vertical channel runs across the base of the postero ventral condyle. This channel houses the sensory canal between the preoperculum and pterotic canals. The metapterygoid is widely separated from the hyomandibula (Fig. 5). Anteriorly, it is connected to the quadrate by a narrow cartilage interface and below the cartilage by a promi- nent dentate suture. The ventral edge contacts the dorsal edge of the symplectic, and the endopterygoid overlies the anterodorsal edge. The symplectic is large (relative to the other suspensorial bones) and lies along the postero- ventral arm of the quadrate (Fig. 5). The posterior end is cartilage-capped and connected by a fibrous band of tissue to the hyomandibula. Anteriorly, the symplectic tapers and lies in a recess in the posteromedial wall of the quadrate. The upper surface is produced into a thin lamina with an irregular dorsal edge. The quadrate is fan-shaped (Fig. 5), its anteroventral angle bears a condyle which articu- lates, via a euarthroidal joint with the corresponding anguloarticular facet. The condyle is strengthened by the thickened ventral margin that is bound by connective tissue to the dorsal edge of the preoperculum. A deep recess in the medial face of the quadrate parallel to its ventral edge accommodates the anterior end of the symplectic. A further recess in the antero- medial wall, dorsal to the condyle, accommodates the large posterior ectopterygoid process. The dorsal and posterodorsal edges of the quadrate are connected by a cartilaginous interface to the endopterygoid and metapterygoid, respectively. The endopterygoid is boomerang-shaped (Fig. 5); its anterior arm lies in a shallow groove along the dorsal surface of the ectopterygoid. The short posterior arm is connected by its ventral edge to the quadrate and to the anterodorsal edge of the metapterygoid. The longer (anterior) arm extends below and beyond the anterodorsal connection of the ectopterygoid to the lateral ethmoid (discussed below; see Fig. 49). The anterior edge of the ectopterygoid is sinusoidal (Fig. 5). A medial facet on the antero- dorsal surface connects it directly with the lateral ethmoid. A groove extends for a short dis- tance along the posterodorsal edge and accommodates the anterodorsal margin of the quadrate. Posteriorly, a horn-shaped process extends from the ectopterygoid to lie within a recess in the medial face of the quadrate. The palatine is a long, flake-like element curved around the lateral face of the vomerine shaft (dermal and endochondral components cannot be distinguished in M. mastacembelus). A weak spur ascends dorsally to connect the palatine with the lateral ethmoid (Fig. 5). Posterior to the small spur the bone becomes dorsoventrally flattened beneath the anterior orbital region. There are no palatine teeth in this species. 22 R. A. TRAVERS a End Met Sym HyoS Ih Hyo HyoS Met End Sym Fig. 5 Mastacembelus mastacembelus, left hyo-pterygoid arch in (a) lateral view, (b) medial view. Opercular series The operculum is characterised by a deeply concave dorsal edge (Fig. 6) which together with the weak, poorly ossified posterolateral flap is tightly sealed to the body-wall by the integu- ment and underlying musculature (see p. 121). Thus, the branchial aperture lies below the suboperculum. The ventral margin of the operculum overlaps the dorsal part of the suboperculum. A large facet on the anterodorsal edge articulates with a hyomandibular condyle and serves as a fulcrum for opercular dilatation, albeit only slight due to its restriction dorsally. A ridge crosses the lateral face and terminates in the dilatator process ventral to the opercular socket. The levator operculi muscle inserts along the dorsal surface of the ridge, and the 'musculus intraoperculi' (which is unique to the mastacembeloids, see below p. 120) inserts along its ventral surface. The base of the opercular socket is pierced by a foramen which carries a ramus of the truncus hyomandibularis (ramus opercularis superficialis facialis). This nerve passes along a short enclosed canal to emerge on the anterolateral face of the operculum. The preoperculum is L-shaped (Fig. 6). Its long, lower arm lies along the curved ventral MASTACEMBELOIDEI I: ANATOMICAL DP ROSFF 23 Op Pbp Fig. 6 Opercular series of Mastacembelus mastacembelus. edge of the symplectic and quadrate, connecting them by its vertical arm to the hyoman- dibula. Anteriorly, the preoperculum is joined to the posterolateral wall of the angulo- articular by a short ligament. Preopercular spines are absent. The ventral edge overlaps the dorsolateral margin of the interoperculum, to which it is loosely joined by connective tissue. The upper arm of the preoperculum is narrow and lies along a deep lateral hyomandibular groove. The lateral face is pierced by 5 pores that open from its sensory canal (3 pores are present on the horizontal and 2 on the vertical limb). The interoperculum is triangular, its broad posterolateral face bevelled anteriorly to a point just posterior to the mandible (Fig. 6); the interopercular ligament connects the anterior tip of the bone to the small retroarticular. Posteriorly, the interoperculum is sloped, dorsome- dially, below the ventral edge of the preoperculum to which it is loosely joined by connective tissue. The suboperculum is weak, its shorter, vertical arm hidden in lateral view by the anterior edge of the operculum and the posterior edge of the interoperculum (Fig. 6). The horizontal arm is broader than the vertical arm and the dorsolateral margin is overlapped by the ventral edge of the operculum. The ventral border is poorly ossified and, since it is not connected to the ventral body wall, it contributes to the posterior opening of the branchial chamber. Hyoid and branchial arches The basihyal is long and spatulate; a low ventral ridge runs along almost the entire length of the bone (Fig. 7). Posteriorly, the ridge lies in a groove along the anterior edge of the basibranchial 1 'keel' and forms a hinge joint. The paired dorsal and ventral hypohyal bones are joined to basibranchial 1 by fibrous connective tissue. The dorsal hypohyal is small and caps the anterodorsal edge of the anterior ceratohyal, to which it is sutured by a number of tongue-like bony flanges (Fig. 7). The medial wall of the dorsal hypohyal is faceted and connects the anterolateral face of basibranchial 1. Below this facet there is a large central foramen for passage of the hyoidean artery. Ven- trally, the dorsal hypohyal is separated from the ventral hypohyal by a cartilaginous interface (Fig. 7). 24 R. A. TRAVERS DHh HAF ACh PCh VHh Fig. 7 Mastacembelus mastacembelus, right hyoid arch; medial aspect. The ventral hypohyal is connected to the anterior ceratohyal by an interdigitating suture and a short band of cartilage (Fig. 7). Its anterior region is laterally compressed and a facet occurs on the medial face articulating with its partner in a median symphysis, anterior to the front edge of the keel on basibranchial 1 . Below this facet is a shallow fossa, which accommodates the anterior end of a large ligament from the urohyal. The anterior ceratohyal is compressed. Its posterior edge is joined to the anterior edge of the posterior ceratohyal by a large tripartite interdigitating suture, above and below which is a short connecting band of cartilage (Fig. 7). Two branchiostegal rays (3rd and 4th) articulate with the lateral face of the anterior cerato- hyal. The 5th branchiostegal is loosely connected to the medial face and the 6th (the weakest) attaches to the anteroventral margin of this bone. A 'berycoid' foramen (McAllister, 1968: 6) is absent. The posterior ceratohyal is also compressed and is approximately triangular in outline (Fig. 7). The 1st and 2nd branchiostegal rays are loosely attached to its lateral face. The distal end is ligamentously connected to the ventral end of the interhyal. The short, hour-glass shaped interhyal connects the posterior end of the hyoid arch (pos- terior ceratohyal) with the suspensorium, at a point between the symplectic and hyoman- dibula. The cartilaginous anterior and posterior ends of this bone have their long axes at right angles to each other. The urohyal is extremely elongated and extends posteriorly from below basibranchial 1 to a point midway along ceratobranchial 5. The anterior end is bifurcated and from each head a large ligament extends forward to the ventral hypohyal. On its dorsal surface immediately posterior to its forked anterior end, is a small ascending process (directed posterodorsally), the tip of which lies below the keel on basibranchial I, and is loosely attached by connective tissue (Fig. 9). Posteriorly, the urohyal divides into four weakly ossi- fied membranous prongs; a short dorsal and ventral prong with two large lateral prongs. The latter are subdivided into three small, posteriorly pointed processes (Fig. 9). There are three ossified and a single cartilaginous basibranchial among the ventral gill arch elements. Basibranchial 1 is cylindical with a deep ventral 'keel' which tapers to a knife-edge and lies partly below basibranchial 2 and the basihyal (Fig. 9). A round facet on the anterolateral surface lies across its junction with the basihyal, and articulates with the medial face of the dorsal hypohyal. Basibranchial 2 is narrow-waisted (Fig. 8). The proximal end of hypobranchial 1 lies in the anterolateral, 'waisted' region. Posteroventrally, basibranchial 2 is united by fibrous tis- MASTACEMBELOIDEI I: ANATOMICAL 25 Cb1-5 Bb4 UTp Bb3 Fig. 8 Mastacembelus mastacembelus, lower gill arch elements; dorsal view. sue to the anterior end of basibranchial 3. A prominent descending process extends from the median anteroventral surface and contacts the posterior edge of the 'keel' on basibran- chial 1 (Fig. 9). A pair of descending processes also extend from each posterolateral corner of basibranchial 2. The tips of these processes are connected, by a pair of converging liga- ments, to the posteroventral edge of the 'keel' on basibranchial 1 (the ventral aorta lies in the midline between these posteroventral processes). Basibranchial 3 is long and relatively narrow; the medial end of hypobranchial 2 contacts the notched anterolateral wall. The posterior end is unossified and forms a rod-like length of cartilage capable of sliding below basibranchial 4 when the branchial arches contract (Fig. 8). Basibranchial 4 is a rhomboid, cartilaginous element (Fig. 8). Its anterolateral face contacts the posteromedial edge of hypobranchial 3, and its posterolateral edges the ends of the 4th and 5th ceratobranchials. Hypobranchials 1 & 2 each have a broad proximal (anteromedial) face faceted for articu- lation with their corresponding basibranchial elements. Hypobranchial 2 is also connected, by a medial flange, to the posterolateral descending process on basibranchial 2. Hypobranchial 3 is characterised by a large anteroventral process extending forward below the 2nd hypobranchial. The anterior tip of this process is ligamentously attached to the pos- terior descending process on basibranchial 2; the ligament merges in the midline with its opposite number to produce a wide, ventral sheet of collagenous tissue. The ventral aorta runs along the dorsal surface of this medial aponeurosis, between it and the basibranchial elements. 26 Bb3 R. A. TRAVERS Bb1 Bb2 Hb3 Bb1K Uh UhAP Fig. 9 Mastacembelus mastacembelus, basihyal and branchial bones in lateral view, right side. The posterior end of each hypobranchial is connected by fibrous tissue to its corresponding ceratobranchial. Small, irregularly positioned dermal toothpatches are supported along the anterior margin of hypobranchial 1 and 2. No toothplate is associated with the dorsal surface of hypobranchial 3. Ceratobranchials 1-5 are rod-like elements; with the exception of the 5th, are all essentially alike. The distal ends of Ceratobranchials 1-4 are each joined by connective tissue to a corre- sponding epibranchial bone. Along the ventral face of Ceratobranchials 1-4 is a hollow channel that accommodates the efferent blood vessels and the bases of the gill filaments. Numerous small, round, dermal toothpatches are supported along the anterior face of Ceratobranchials 1-4. The 5th ceratobranchial bears a large fused toothplate ('lower pharyngeal jaw'). This toothplate is expanded posteromedially, but does not contact its partner in the midline. The medial edge of the expanded toothplates and the posteromedial margin of the bone are joined to the oesophagus. The toothplate bears acrodont caniniform teeth graded in size, with the largest along the medial edge. The posterior end of ceratobranchial 5 forms a relatively short 'muscular process' (Liem, 1974). A broad sheet of fibrous tissue connects the posterolateral edge to the lateral face of the cleithrum. The dorsal gill arch elements lie posterior to the cranium. Epibranchials 1 and 2 are each characterised by wide anterior edges; a round dermal tooth- plate is supported on the anteroventral face of each (Fig. 10). Epibranchials 3 and 4 both bear an ascending uncinate process. The dorsal tips of these processes are connected by a short collagenous strand of tissue. Apart from a short lateral region, the dorsal edge of each epibranchial is free of gill filaments. Pharyngobranchials 2 and 3 are the only ossified pharyngobranchial (infrapharyngobran- chial) elements present. The posterior end of pharyngobranchial 2 is attached by a colla- genous strand to the medial end of epibranchial 2. This collagenous strand is also connected to the tip of a short process on the lateral margin of pharyngobranchial 3. Pharyngobranchial 3 extends anteriorly from this process to lie parallel with the anterior end of pharynobran- chial 2. A collagenous strand of tissue connects their anterior tips with the medial end of epibranchial 1 (Fig. 10). There is no trace of an interarcual cartilage (Travers, 1981) between epibranchial 1 and pharyngobranchial 2. The posterior end of pharyngobranchial 3 is broad and connected to the medial end of epibranchial 3. A small cartilaginous element lying posterior to pharyngobranchial 3 (between it and the medial end of epibranchial 4) is interpreted as a cartilaginous 4th pharyngobranchial. The MASTACEMBELOIDEI I: ANATOMICAL 27 a Eb4 Tp4 Pb2 Eb1 Eb3 UP Eb4 Pb2 Pb3 Fig. 10 Mastacembelus mastacembelus, right upper gill arch elements in (a) dorsal view, (b) medial view. largest toothplate of the dorsal gill arch elements is fused to the ventral face of pharyngobran- chial 3. A smaller toothplate is fused to the ventral face of pharyngobranchial 2. A further toothplate lies ventral to the cartilaginous pharyngobranchial 4. The toothplates on the pharyngobranchial bones, together with the free 4th pharyngobran- chial toothplate, constitute the 'upper pharyngeal jaws'. The dentition of these elements is similar to that found on ceratobranchial 5 which they oppose. There are no gill rakers on the branchial arches. Pectoral girdle The pectoral girdle lacks a bony connection to the neurocranium and lies posterior to it adjacent to the 3rd and 4th abdominal vertebrae. The thin supracleithrum is relatively long and narrow (Fig. 1 1). The ventral end overlaps the dorsolateral wall of the cleithrum to which it is loosely attached. A portion of the postcranial sensory canal system passes longitudinally through its dorsal tip. The cleithrum is the largest bone of the pectoral girdle. It has a vertical dorsolateral shaft and a ventral limb which curves anteromedially to contact its partner in a median symphysis. The scapula and coracoid lie just distal to a trough-like region in the lateral face (Fig. 1 1). 28 R. A. TRAVERS Sc ScaF PFR Cor Fig. 1 1 Mastacembelus mastacembelus, lateral view of pectoral girdle; left side, with two post- temporal tubules. Baudelot's ligament extends between the basicranium and dorsomedial face of the cleithrum and the ventromedial face of the supracleithrum. The scapula is almost square in lateral outline. A large foramen pierces its anterolateral face; the nerve trunk to the pectoral fin rays passes through this opening. The cartilaginous anterior edge lies within the dorsal region of the cleithral trough. The posterior edge supports the 1st and 2nd radials and dorsal to these a slight posterior projection of the scapula articu- lates directly with the base of the primary fin ray (Fig. 1 1). The scapula and coracoid are separated by a narrow cartilage interface. The coracoid is a narrow-waisted, flat bone; the lower region drawn out both anteriorly and posteriorly into pointed processes. The posterior process extends to a point below the posterior edge of the radials. The dorsal cartilage interface extends along the posterodorsal edge and supports the 3rd and 4th radials. The four radials (actinosts) are short, spool-like, independent elements; the smallest lying dorsally (1st). The ends of each radial are cartilaginous and form a shallow facet for articula- tion anteriorly with the scapula and coracoid (as described above) and posteriorly with the base of each fin ray. The pectoral fin has 22 segmented fin rays; each composed of independent halves and branched distally. The innermost halfrays (posterior) each have a ventral proximal process that overlaps the lower neighbouring halfray (Fig. 1 1). Distal to this process is a 2nd triangu- lar flange that overlaps the upper neighbouring element. The outer (anterior) halfrays also have a ventral bony lip overlapping the lower neighbouring element. Fin movement results in a complex interlocking of these flanges. MASTACEMBELOIDEI I: ANATOMICAL 29 Vertebral column The total vertebral count is 86, viz., 38 abdominal (precaudal vertebrae), 47 caudal and the fused ural and first preural centra. Following the method of Greenwood (1976: 65) the first caudal vertebra is identified as that with which the first anal pterygiophore articulates. The first four abdominal vertebrae are the most distinctive of the entire series (Fig. 12). Their broad neural arches are pierced by numerous perforations. The anterior half of the 1st centrum is rounded to form a hemispherical condyle. This condyle articulates with the tripartite occipital socket in a 'ball and socket' joint. The first neural arch contains a distinctly large foramen just above its point of fusion with the centrum. The neural spines of the first four abdominal vertebrae are laterally compressed and elon- gated. The 1st abdominal vertebra has the largest neural spine (4-5 times wider than the spine on the 5th vertebra); the anterior and posterior edges are approximately parallel and the dorsal edge produced into 3 separate peaks. The 2nd, 3rd and 4th neural spines have 2 dorsal peak-like processes, and the posterior edge of the 2nd is deeply notched. Pre- and postzygapophyses are well developed on all but the 1st abdominal vertebra. Along the abdominal vertebrae there are a total of 3 pairs of epicentral and 1 pair of epipleural ribs. The epicentral ribs occur on the 1st to 4th vertebrae and epipleural ribs on the 4th only. The 1st epicentral is lodged in a recess on the lateral wall of the 1st centrum; all other epicentral ribs are supported by their anterior ends lying in a shallow channel along the dorsal surface of the lateral parapophyses. Lateral parapophyses are present on all abdominal vertebrae except the 1 st, and decrease in size posteriorly. The Pleural ribs are all supported in a groove along a ventral arm of the lateral parapo- physes (Fig. 12). By the 10th abdominal vertebra the lateral parapophysis is reduced to a low notch and the ventral arm developed into a prominent, ventromedially curved parapopyhysis that sup- DS(I) ENS HHAVtd) EcR LP Fig. 12 Mastacembelus mastacembelus, anterior abdominal vertebrae with first three dorsal spines; lateral aspect, left side. 30 R. A. TRAVERS ports a large (posteriorly tapered) pleural rib. By the 13th abdominal vertebra the pleural ribs are no longer medially curved. On the 6th and all succeeding abdominal vertebrae there is also a short descending process on the ventral face of the centrum (posterior half). The abdominal centra are characterised by their asymmetry as the posterior region of each appears to have been drawn out. However, the asymmetry of the centra is gradually lost posteriorly and the last 10 caudal vertebrae are symmetrical. The parapophyses on the 1st caudal vertebra (Fig. 13) are connected in the midline by a short band of fibrous tissue (forming a rudimentary haemal arch). These parapophyses are also branched and support the massive pterygiophore carrying the 1st and 2nd anal spines. Dorsal and anal fins There is a total of 35 dorsal spines and supporting pterygiophores associated with the 4th to 38th abdominal vertebrae (excluding the 3 1st and 35th) and the 2nd and 3rd caudal ver- tebrae. The spines are relatively short, stout structures, curved posterodorsally. Anteriorly, each spine is held in position by the distal end of the supporting pterygiophores, which are fused and form a stout bone that tapers to a point anteroventrally. The distal region of these pterygiophores bears a pair of prominent hooks that lie (laterally) on either side of the spine and hold its base firmly in position (Fig. 13). The proximal end of each spine bears a pair of small anterolateral processes around which the distal pterygiophore is hooked; a pair of lateral ridges present along the pterygiophore, separate the erector from the depressor DSPt NS PR DPt Fig. 13 ASPt Mastacembelus mastacembelus, abdominal/caudal vertebral junction and associated dorsal and anal spines; lateral aspect, left side. MASTACEMBELOIDEI I. ANATOMICAL 31 muscles. A ligament passes from the base of the spine along the anterior edge of the supporting pterygiophore and contributes to the articulation between these elements. There are 3 anal spines (Fig. 13); all are similar in morphology to the dorsal spines except that the 1 st and 2nd share a massive pterygiophore. This pterygiophore is supported by the rudimentary haemal arch of the 1st caudal vertebra. The non-spinous dorsal and anal fins are composed of 70-73 and 74-78 segmented rays respectively. They extend from the posterior spinous rays to the dorsal and ventral edge of the caudal fin. Each ray is supported by a pterygiophore system composed of 3 elements. On the whole, most neural and haemal spines are associated with 2 pterygiophores; hence each supports 2 fin rays (by the connection of a proximal pterygiophore to the anterior and posterior edges of each neural and haemal spine). The proximal pterygiophore is a long, ventrally pointed bone much smaller and weaker in comparison with its spine supporting counterpart. The distal end is fused to a cone-shaped medial pterygiophore, the two forming a single unit (Fig. 13). The dorsal surface of the medial pterygiophore is flat and the small, independent distal pterygiophore of the preceeding fin ray articulates with it. The posterior end of the medial pterygiophore is collagenously joined to the distal pterygiophore of the same ray. The distal pterygiophore is a small saddle-shaped independent structure, composed of sep- arate halves. It lies between the base of the fin ray and the supporting medial pterygiophore element. Caudal fin The caudal fin rays lie posterior to the last ray of the dorsal and anal fins, to which they are joined by a thin membrane. The hypural bones fan out from the fused ural and first preural centra and are composed of 4 relatively large, autogenous elements (2 above and 2 below the lateral line), and an extremely small splint of bone along the dorsal edge of the upper hypural (Fig. 14). Ventral to these lies an independent parhypural. A large vascular canal passes through the head of this bone (Fig. 1 4). SnL NS PU+U PU2 AHS VCPH Ph H1 H2 PCR Fig. 14 Mastacembelus mastacembelus, caudal fin skeleton; lateral aspect, left side. 32 R. A. TRAVERS A uroneural (1) is fused along the dorsal edge of the fused ural and preural vertebra and is tapered to a fine point posteriorly. A second, sickle-shaped uroneural bone (2) lies lateral to the first and the base of the dorsal hypural. A long epural extends posteriorly from the reduced neural arch on the fused ural and preural centra to the anterior region of the fin rays. Between this long epural and the fused ural and preural vertebra is a second, smaller epural element. The 2nd preural vertebra bears an autogenous haemal arch from a deep V-shaped notch in the lateral wall of the centrum. The haemal spine on this arch is long and directly supports the ventral caudal fin ray. The neural arch is large and fused to the centrum. Two spines extend from this arch and may indicate that intervertebral fusion has occurred. These neural spines are long but do not contribute to the support of caudal fin rays. There are 19 segmented, unbranched caudal fin rays (9 forming the upper lobe and 10 the lower lobe of the caudal fin). Squamation Small cycloid scales cover the body and head, except for its dorsal surface, i.e. the nasals, frontals & parietals. Osteology of Chaudhuria caudata This description is based on three specimens (see Table 3). Two individuals (38 mm. and 42 mm. standard length) from the collections at the BM(NH) are alizarin stained only. A third specimen (on loan from the MCZ) was double stained and is 43 mm. long. In this alizarin/alcian blue transparency numerous mature eggs (approx. 30) are visible in the pos- terior region of the body cavity, indicating that specimens of Chaudhuria at this size are adult. Neurocranium Ethmovomerine region The supraethmoid is a particularly elongate bone; it consists of a laterally compressed region separating the olfactory sacs, and a short posterodorsal process lying between the anterior tips of the frontal (Fig. 1 5ai). The anterodorsal edge is indented and supports a relatively large tapered rostral cartilage. The anterior tip is divided into two short, blunt processes. Ventrally this region is fused to the anterodorsal edge of the vomer; posteroventrally it remains cartilaginous and extends along the anterodorsal surface of the parasphenoid and into the orbital cavity as a septal cartilage. The vomer is developed anteriorly into a facet which extends around the tip of the bone. The anterolateral region of this facet articulates with the medial face of the ascending process of the premaxilla. The vomerine shaft lies in a ventral groove in the parasphenoid and extends posteriorly to a point adjacent to the anterior end of the prootic. Each lateral ethmoid is a vertical, plate-like bone pierced by a large central opening. The medial edge contacts its partner in the midline dorsal to a cartilaginous septal region of the supraethmoid. Short anterior and posterior processes extend from the dorsal edge of the lateral ethmoid and are covered by the nasal and frontal respectively. The narrow ventro- lateral face is joined syndesmotically to the posterodorsal tip of the 1st infraorbital. The flattened nasal slopes ventrolaterally and covers the olfactory cavity; it is poorly ossi- fied (especially anteriorly). The medial edge is loosely connected to the dorsal margin of the supraethmoid, and the lateral edge to the 1st infraorbital bone (Fig. 15aiii). Posteriorly it extends as a flattened projection above the lateral ethmoid and anterior surface of the frontal. Orbital region The pterosphenoid and basisphenoid are absent. The parasphenoid has a long, narrow MASTACEMBELOIDEI I: ANATOMICAL 33 anterior process which terminates ventral to the lateral ethmoids (Fig. 1 5aii). It lacks a dis- tinct ascending arm and has only a low lateral wall contacting the posteroventral edge of the prootic; it is unattached to any other bone. Posteriorly, the lateral wall is reduced to a shaft ventral to the median connection between the prootic bones. From this region the parasphenoid is divided into a pair of long, needle-like processes which extend to the postero- ventral edge of the basioccipital. A low ventral ridge on the basioccipital lies between these processes. Adjacent to the lateral commissure the dorsal margin of the parasphenoid is notched for passage of the internal carotid artery. The 1st infraorbital bone is the only poorly ossified element of the infraorbital series present. It tapers anteriorly and contacts the ventral edge of the nasal and dorsal surface of the maxilla (Fig. 16a). The posterodorsal edge is indented and surrounds the ventral rim of the posterior olfactory opening. The posterior edge of this opening is formed by an ascending posterodorsal process on the 1st infraorbital. The medial tip of this process articulates synchondrally with the lateral ethmoid. Otic region The prootic is a particularly long bone and has a wide, tapered, anterior process extending to the orbital cavity. (Fig. 15ai). The dorsal connection with the sphenotic is interrupted by the single foramen in the pars jugularis. A slender lateral commissure arches across the centre of this foramen. Anterior to the trigeminofacialis chamber the prootic tapers into a long rostrodorsally directed process. Its dorsolateral face is pierced by a pair of round foramina which open into a medial groove along the anteromedial face of the process, and extend to its tip. A shallow fossa in the posterodorsal margin of the prootic combines with a similar one in the sphenotic to accommodate the anterior hyomandibular condyle. Posteriorly, the prootic borders the pterotic, exoccipital and basioccipital bones and houses the anterior third of the sacculus. The sphenotic lies between the dorsal edge of the prootic and the dorsolateral edge of the frontal. It has a long anterior projection extending into the orbital cavity, and terminates as a broad, blunt process, slightly posterior to the tip of the prootic anterior process (Fig. 1 5ai). The ventral edge forms the anterodorsal rim of the single foramen in the pars jugularis. A postorbital process is absent. The posterior edge borders the pterotic, and a posterodorsal process extends medially below the parietal to connect, synchondrally, the tip of a process apparently originating from the ventral surface of the supraoccipital. The pterotic is an inflated bone, due to a medial cavern that encloses the horizontal semicircular canal, with a grooved ventral surface that accommodates the posterior hyoman- dibular condyle (Fig. 15aii). The dorsal edge is overlapped by the dorsolateral margin of the parietal. Ventrally it contacts the prootic and exoccipital and forms with these bones a relatively deep lateral recess. The posttemporal fossa is absent and posteriorly the pterotic borders the epioccipital. The epioccipital lies between the exoccipital and pterotic and dorsally contacts the posterolateral edge of the supraoccipital and posterior edge of the parietal. The inner face of the epioccipital houses the posterior semicircular canal which causes its relatively wide dorsolateral face to be somewhat bullate. The exoccipital has a perforated dorsal surface which is prevented from contacting its partner in the midline by a posterior extension of the supraoccipital. The posterolateral face of the bone has three major foramina, viz those of the glossopharyngeus, occipitospinal and vagus nerves. This region is curved ventromedially and contacts its partner in the midline dorsal to the basioccipital. Below their median connections the ventral surface of each exoccipital is developed into a slightly concave, deltoid facet. These facets, with a similar one from the basioccipital, form the tripartite occipital facet, a concave socket that articulates with the rounded anterior end of the 1st abdominal centrum (Fig. 21aii). The ventral region of the exoccipital bears a small 34 R. A. TRAVERS process which is directed posteriorly and extends beyond the posteroventral edge of the basioccipital. The basioccipital is large, relative to the size of the other basicranial bones, and contacts the exoccipital and prootic (Fig. 1 5aii). The long ventral processes on the parasphenoid pass across its ventral surface on either side of a low longitudinal ridge. The posterodorsal surface is faceted and contributes to the tripartite occipital socket. The supraoccipital is the major element in the roof of the basicranium (Fig. 1 Saiii). It is a flattened bone that is transversely convex and bounded on either side by the posterior N Sue EC IFF PrAP LE N Sue Fig. 15 Neurocranium in (a) Chaudhuria caudata, and (b) Pillaia indica: right lateral view (ai & bi), ventral view (aii & bii) and dorsal view (aiii & biii). MASTACEMBELOIDEI I: ANATOMICAL 35 portion of the frontals, the parietals, epioccipitals and the dorsomedial edge of the exoccipi- tals. However, none of these surrounding bones overlaps the supraoccipital margin. Its posterior edge contributes to the rim of the foramen magnum. There is no sign of the extrascapula (lateral or medial) or the posttemporal bones. The flattened dorsal surface of the frontal narrows anteriorly as a short process that termi- nates below the posterior end of the nasal (Fig. 15aiii). Posteriorly, the frontal is long and curved ventrolaterally. A descending lamina is absent. Sph Apto So Par PPP riii Apto Sue 36 R. A. TRAVERS The parietal has a flattened, unsculptured dorsal surface that is relatively broad compared with the other roofing bones (Fig. 1 5aiii). It lacks a posterolateral flange and is surrounded by the supraoccipital, frontal, pterotic and epioccipital bones. A notch along its postero- medial edge forms, with the margin of the supraoccipital, a small dorsal opening. There is no sign of the cephalic sensory canal system in any neurocranial bones. The soma- tic component passes through the tip of the supracleithrum and appears to terminate just posterior to the cranium. Jaws The upper jaw in Chaudhuria, based on Annandale's (1918) original description, was assumed by Yazdani (1978: 284) to consist of a single bone; however, this is not the case. The premaxilla is a long, narrow, weakly curved bone, and has a low stump-like ascending process on its anterodorsal surface (Fig. 1 6a). The ventral surface has a narrow alveolar sur- face that bears 2 rows of long, weak villiform teeth (decreasing in size posteriorly). The maxilla is a relatively large bone (compared with the size of the premaxilla; Fig. 16a). Its anterior end extends to the posterior edge of the premaxillary symphysis and is connected to the premaxilla ascending process and lateral facet on the head of the vomer. Posteriorly the maxilla overlies the lateral face of the coronoid process on the dentary. The dentary is relatively short. Its symphysis lies in the vertical posterior to the premax- illary symphysis. A prominent symphysial process descends from the anteroventral edge. Posteriorly, the dentary divides into an upper coronoid and lower ventral arm (Fig. 16a). The coronoid region is developed into a tall, narrow process. The dorsal surface anterior to the coronoid process is alveolate and bears 3 rows of villiform teeth, decreasing in number and size posteriorly. The ventral arm of the dentary extends posteriorly as a long pointed process lying below the margin of the anguloarticular. From the ventral edge of this process a further short posteromedially directed process may develop. The region between these processes may be bridged by partly ossified tissue. The anguloarticular is long and pointed (Fig. 1 6a). Its dorsal edge is straight, apart from a low projection on the anterior edge of the posterodorsal facet. Meckel's cartilage lies along the medial face, and passes into the dentary. The retroarticular is a small, L-shaped bone (its shorter horizontal limb extending anteriorly). The dorsal surface of the vertical limb articulates synchondrally with the posteromedial face of the anguloarticular facet (Fig. 16a). The interopercular ligament is connected to the posterior edge. The coronomeckelian is a short rod of bone that lies on the posterodorsal surface of Meckel's cartilage but does not protrude above the dorsal edge of the anguloarticular (Fig. 16a). The anterior end of the tendon from part A3 of the adductor mandibulae inserts on the coronomeckelian. Hyopalatine arch The hyomandibula is a short, stout bone, its dorsal surface produced into two condyles which articulate with the lateral face of the neurocranium, and its posterodorsal edge produced into a third condyle which articulates with the operculum (Fig. 1 7a). The descending hyoman- dibular shaft is short and is joined to the symplectic and interhyal medial to the preopercu- lum. A wide flange anterolateral to the shaft is connected anteriorly to the metapterygoid and ventrally to the posterodorsal edge of the symplectic. A large foramen for the truncus hyomandibularis pierces the lateral wall of the hyomandibula, ventral to its anterior condyle. The symplectic is a rod-like bone without dorsal lamina, and does not extend forward to the quadrate (Fig. 1 7a). Its dorsal edge is connected to the ventral edge of the metapterygoid, and ventrally it lies along the lower limb of the quadrate, passing posteriorly on the medial aspect of the preoperculum. MASTACEMBELOIDEI I: ANATOMICAL 37 01 MC Aa DPP Mx+Pm Fig. 16 Upper and lower jaw bones in (a) Chaudhuria caudata and (b) Pillaia indica; lateral view, left side. The metapterygoid lies close to the anterior edge of the hyomandibula. Its anterior edge is connected by a cartilaginous interface with the quadrate. The anterodorsal corner has a slight projection that overlies the dorsal edge of the quadrate. The quadrate is large in comparison with the other suspensorial bones. Its anterior edge is notched and ventrally forms a stout condyle which articulates with the anguloarticular facet. This condyle is strengthened by the thickened ventral region of the quadrate. An endopterygoid is absent. 38 R. A. TRAVERS a HyoAF IViGt HyoAF Hyo Q Fig. 17 Hyopalatine arch, in (a) Chaudhuria caudata and (b) Pillaia indica; lateral view, left side. The ectopterygoid is particularly long with a relatively narrow lateral face whose posterior region lies medial to the anterior edge of the quadrate (Fig. 17a). The anterior limb is curved medially (ventral to the lateral ethmoid) and has its medial face connected to the vomerine shaft. This is the anterior suspensorial articulation with the neurocranium as there is no connection between the ectopterygoid and lateral ethmoid. The palatine is absent. Opercular series The preoperculum is crescentic, lacking distinct vertical and horizontal arms; the lateral face is wide (Fig. 1 8a). Dorsally, it is tucked within a deep groove on the lateral face of the hyomandibula. The interoperculum is connected ligamentously to the retroarticular and has a poorly ossified ventral margin. The suboperculum has a thin dorsal arm that ascends between the interoperculum and operculum, apart from this arm it is poorly ossified. The operculum is developed anterodorsally into a prominent concave facet for articulation with the posterior hyomandibular condyle (Fig. 1 8a). The ridge on its lateral face extends from the base of the facet and forms a distinct dilatator process. The dorsal edge of the operculum is notched and its posteroventral margin is poorly ossified. MASTACEMBELOIDEI I: ANATOMICAL 39 Op Pop lop Fig. 18 Opercular series of (a) Chaudhuria caudata and (b) Pillaia indica. Hyoid and branchial arches The basihyal is spatulate with a low ventral ridge, and has its posterior end connected to the anterior end of basibranchial 1 (Fig. 20ai). The dorsal and ventral hypohyalbones are connected to the posterolateral face of the basi- hyal across its border with basibranchial 1 (Fig. 20ai). These elements are connected to each other and the proximal end of the anterior ceratohyal by a narrow cartilaginous interface. The dorsal hypohyal is pierced by a large central foramen for the passage of the hyoidean artery. Dorsal to this foramen its medial face is faceted and articulates with the anterolateral face of basibranchial 1 . The compressed anterior region of the ventral hypohyal has a medial facet that contacts its partner in the midline ventral to the posterior end of the basihyal. The anterior ceratohyal is hatchet-shaped, in lateral view, and supports the base of the 3rd and 4th branchiostegal rays distally on its wide anterior face. (Fig. 19a). The narrow proximal end supports the 1st and 2nd branchiostegal rays. A single process extends from its lateral end and is housed in a recess on the posterior face of the posterior ceratohyal. Apart from this projection the ceratohyals are connected only by a straight suture incorporating a wide cartilaginous interface. The posterior ceratohyal has a wide ventral lip that supports, on its posterior face, the base of the 1st and 2nd branchiostegal rays. The distal end of this bone is connected by a tough ligament to the interhyal. 40 R. A. TRAVERS The interhyal is a short rod-shaped bone that is joined to the fibrous connective tissue between the symplectic and hyomandibula, medial to the preoperculum (Fig. 19a). The urohyal is forked anteriorly with each tip ligamentously connected to the ventral hypohyal. Posteriorly, it increases in depth and is relatively short, terminating at a point ventral to basibranchial 4 without developing into prong- like processes. Basibranchial 7 is a short, cylindrical element without a ventral keel. Anterolaterally it articulates with the medial face of the dorsal hypohyal, and posteriorly with basibranchial 2 (Fig. 20ai). DHh ACh PCh BR VHh DHh ACh PCh VHh Fig. 19 Hyoid arch, in (a) Chaudhuria caudata and (b) Pillaia indica; lateral view, left side. Basibranchial 2 is rod-like and the medial face of hypobranchial 1 connects to its antero- lateral face. There are no ventral processes and posteriorly it is joined to basibranchial 3. Basibranchial 3 is long and its tapered posterior end terminates in a cartilaginous tip (Fig. 20ai). The medial end of hypobranchial 2 is connected to the antero lateral face of basibran- chial 3. Basibranchial 4 is a small cartilaginous element (Fig. 20ai). Its anterolateral face is con- nected to the medial end of hypobranchial 3, and its posterolateral face to the medial end of ceratobranchial 4. Hypobranchials 1 and 2 are relatively short rod-like bones distally connected to the anterior (medial) end of their corresponding ceratobranchials (Fig. 20ai). Hypobranchial 3 is shorter and broader than its anterior counterparts; its anterior process is relatively short and does not extend below hypobranchial 2 (Fig. 20ai). A round toothplate with small caniniform teeth is fused to the dorsal surface. Ceratobranchials 1-5 are long, rod-like bones, all, apart from the 5th, essentially similar. The distal ends of ceratobranchials 1-4 are joined by connective tissue to the distal ends of the corresponding epibranchial bones. The ventral surface of each ceratobranchial is grooved and accommodates the bases of the gill filaments. MASTACEMBELOIDEI I: ANATOMICAL 41 Ceratobranchial 5 carries a fused toothplate which has a slight medial expansion and bears relatively large caniniform teeth (Fig. 20ai). Posterior to its toothplate, ceratobranchial 5 curves dorsolaterally to form a process for muscle attachment. All dorsal gill arch elements lie posterior to the neurocranium, as do some of the ventral elements. Epibranchials 1 & 2 are but slightly curved, narrow bones (Fig. 20aii). The medial end of epibranchial 1 is connected to the anterior end of the small rod-like pharyngobranchial 1 , and epibranchial 2 connects with its posterior end. Epibranchials 3 and 4 both have an ascending uncinate process (Fig. 20aii). The dorsal tips of these processes are connected by a short strand of collagenous tissue. The medial end of epibranchial 3 is connected to the posterolateral margin of pharyngobranchial 3. The medial end of epibranchial 4 is broad and is joined to the wide posterior end of pharyngobranchial 3. Pharyngobranchial 2 and 3 are the only pharyngobranchial (infrapharyngobranchial) bones present. Pharyngobranchial 2 is a small, untoothed element that lies between the proximal ends of epibranchials 1 and 2 (Fig. 20aii). Pharyngobranchial 3 is a much larger bone and bears a large toothplate fused to its ventral surface. The proximal end of pharyngo- branchial 3 is connected to the distal end of pharyngobranchial 2 and together these are joined to the tip of epibranchial 2. The distal end of pharyngobranchial 3 is broad and con- nected to the wide proximal face of epibranchial 4. The proximal end of epibranchial 3 is not connected to the distal end of pharyngobranchial 3 but is connected to its posterolateral margin. A large toothplate lies below the proximal end of epibranchial 4 and is the pharyngo- branchial 4 toothplate, although there is no sign of its corresponding bone. This toothplate and that on pharyngobranchial 3 have relatively large caniniform teeth with posteriorly directed tips. Pectoral girdle The pectoral girdle lies posterior to the neurocranium, adjacent to the 3rd and 4th abdominal vertebrae. It lacks a posttemporal connection to the neurocranium and there are no ppsttem- poral canal tubules surrounding the postcranial sensory canal anterior to the supracleithrum. The supracleithrum is a small sinusoidal element (Fig. 21ai). The postcranial latero- sensory canal passes through its dorsolateral face; ventrally it overlaps the dorsolateral face of the cleithrum to which it is loosely connected. The cleithrum is bowed and has a narrow lateral face. Dorsally it contacts the supra- cleithrum, ventrally it meets its partner in a median symphysis (Fig. 21ai). Apart from these two bones the pectoral girdle consists only of two indistinct cartilaginous elements that lie posterior to the cleithrum, are partly fused anteriorly and appear to support the fin rays. These rays are indistinct in the specimens examined although Annandale & Hora (1923) described 7 segmented pectoral fin rays in Chaudhuria. Vertebral column The total vertebral count is 72, viz., 25 abdominal, 46 caudal and the fused ural and first preural centra. The unusual form of the vertebrae in Chaudhuria has been described by Annandale (1918). The first 6 abdominal vertebrae have antero-posteriorly expanded neural spines (Fig. 21 aii). Those on the subsequent centra are subdivided into an anterior and posterior peak, giving the neural arch on these vertebrae the appearance of having two spines. A short neural projection anterior to the spine occurs on all abdominal vertebrae apart from the lst-6th. The anterior spine is directed dorsally and less backwards than the posterodorsally directed posterior spine. It decreases in height posteriorly and is absent from the caudal vertebrae apart from a slight projection on the first three or four of these elements. The neural arches of the anterior abdominal vertebrae have a densely perforated lateral surface. The anterior end of the 1 st abdominal centrum is rounded to form a hemispherical condyle that articulates with the tripartite occipital socket in a 'ball and socket' joint. 42 R. A. TRAVERS CbSMP Cb1 Bb4 bi Bb1 Bh CbSMP Bb1 Pb3 Bh Pb2 Fig. 20 Hyobranchial arches in (a) Chaudhuria caudata and (b) Pillaia indica; dorsal view of lower bones (ai & bi), and upper bones (aii & bii). Pre- and postzygapophyses are well developed on all but the 1st abdominal vertebra. Laterally directed parapophyses occur on this and all subsequent abdominal vertebrae; apart from those on the lst-3rd vertebrae, their tips curve ventrally. Epicentral ribs occur on the 1 st abdominal vertebra only, and epipleural ribs are absent. MASTACEMBELOIDEI I: ANATOMICAL 43 Pleural ribs are present on the 4th and all succeeding abdominal vertebrae. They are sup- ported in a groove along the posterior face of the parapophyses. A small bone lies posterior to the tip of the parapophysis on the 3rd abdominal vertebra and may represent a pleural rib. The caudal vertebrae have short, narrow neural and haemal spines. The abdominal and caudal centra are characterised by their asymmetry which is gradually lost posteriorly. Dorsal and anal fins Dorsal and anal spinous rays and their supporting pterygiophores are absent. Forty dorsal and anal branched fin rays extend from a point above and below the abdominal/caudal vertebral junction to the 7th or 8th preural vertebra. Each fin is supported by a pterygiophore system composed of 3 elements; a large well ossified proximal pterygiophore fused to a cartilaginous medial pterygiophore, and a small independent distal pterygiophore. The lack of fin rays (and their supporting pterygiophores) on the posterior 6 or 7 caudal vertebrae is a diagnostic feature of Chaudhuria originally described by Whitehouse(1918). Caudal fin The caudal fin is distinct from the dorsal and anal fins and is composed of 8 segmented fin rays. Two hypural bones (possibly composed of hypurals 1 + 2, and 3 + 4 + 5 + 6) fan out from the fused ural and first preural centra (Fig. 23a). These elements are autogenous and each supports 4 fin rays along its cartilaginous posterior margin. A small parhypural is fused along the ventral edge of the hypaxial hypural. The uroneural is small and appears to be fused along the dorsal edge of the fused ural and first preural centra. There is a single epural bone. The 2nd preural vertebra has a fused neural and haemal arch with short spines which do not support fin rays. Squamation The body is entirely scaleless. Osteology of Pillaia indica This description is based on two specimens (both on loan from the ZSI; see Table 3). The larger specimen (68mm. standard length) is poorly preserved and stained (alizarin only). The second individual is smaller (only 44.5 mm. long) but has responded well to both stains (alizarin & alcian blue), and its internal anatomy is clearly visible. Neurocranium Ethmovomerine region The supraethmoid is similar to that described in Chaudhuria (p. 32 Fig. 1 5ai) apart from a notch in the anterodorsal edge which houses a small rostral cartilage (Fig. 1 5bi). The vomer is curved posteroventrally and extends to a point adjacent to the middle of the ascending lateral walls on the parasphenoid (Fig. 1 5bi). The long anterior arm of the ectopterygoid lies along the posterolateral face of the shaft (discussed below). Each lateral ethmoid consists of a thin medial wall from which a stout, curved strut arches laterally giving it a somewhat tubular shape (Fig. 1 5bi). The medial wall contacts its partner in the midline, dorsal to the cartilaginous region of the supraethmoid, and the lateral face articulates syndesmotically with a medial facet on an ascending process on the 1st infra- orbital bone. Below this connection the lateral ethmoid is drawn out into a tapered antero- ventral process that lies along the dorsolateral margin of the vomerine shaft. The anterior end of the suspensorium lies adjacent to this process, but there is no direct contact. 44 R. A. TRAVERS The nasal is a weakly ossified, flattened bone (Fig. 15bi) that slopes ventrolaterally and overlies the olfactory cavity in a manner corresponding closely to that in Chaudhuria (Fig. 15ai). A number of small, irregular pores pierce the posterodorsal surface. Orbital region The lateral face of the orbital region is open and there is no sign ofpterosphenoidor basisphe- noid bones. The parasphenoid has a short anterior process, possibly associated with the small orbital cavity, which is bent dorsorostrally and terminates at a point below the lateral ethmoid (Fig. 1 5bii). A wide lateral wall ascends from the parasphenoid and, apart from con- tacting the posteroventral edge of the prootic, is unattached to any other bone. Posteriorly, the lateral wall narrows to a reduced shaft and from this region the parasphenoid is divided into a pair of long, needle-like processes which extend across the posteroventral edge of the basioccipital. The 1st infraorbital bone is the only element of the infraorbital series. Ventrally it is connected to the dorsal surface of the upper jaw element. Otic region The prootic lies between the posterolateral wall of the parasphenoid and the sphenotic. The trigeminofacialis chamber is similar to that described in Chaudhuria (p. 33), but anterior to it the prootic in Pillaia has a short, blunt projection that is unattached to any other bone. The posterior region of the prootic borders the pterotic, exoccipital and basioccipital bones and houses the anterior third of the relatively large sacculus. The sphenotic has a long tapered anterior projection that passes along the dorsolateral edge of the frontal (Fig. 1 5bi). The tip of this process extends to a point adjacent to the anterior end of the parasphenoid lateral wall. This region of the sphenotic is unconnected to any other bone. The ventral edge contacts the prootic and forms the anterodorsal rim of the single large foramen in the pars jugularis. A low postorbital process dorsal to the lateral commissure in the trigeminofacialis chamber, is just discernible. The posterior position of this process (relative to the orbit) illustrates that the main region of neurocranial elongation in Pillaia is precommissural. Posterior to the process the neurocranium is of more typical perciform proportions. The pterotic has an inflated lateral face and the dorsal edge is overlapped by the dorso- lateral margin of the parietal. The ventral surface is grooved and accommodates the posterior hyomandibular condyle (Fig. 1 5bi). Below this groove the pterotic contacts the prootic and exoccipital. There is no posttemporal fossa although the ventral margin forms part of the roof of a recess in the lateral wall of the basicranium. The epioccipital is small and forms, in conjunction with the exoccipital and supraoccipital, the posterodorsal wall of the basicranium (Fig. 15bi & iii). The dorsomedial process on the exoccipital is prevented from contacting its partner in the midline by the posterior end of the supraoccipital. The dorsal surface is pierced by numerous small perforations. Three major foramina pierce the posteroventral face. Below their midline connection each exoccipital has a somewhat concave deltoid facet which con- tributes to the tripartite occipital facet (a concave socket) that articulates with the rounded anterior half of the first abdominal centrum (Fig. 21bii). The large basioccipital relative, that is, to its size in other mastacembeloids, contacts the prootic anteriorly and the exoccipital dorsally. The tips of the parasphenoid ventral processes extend beyond its posteroventral edge. A facet on the posterior face contributes to the occipital facet. The supraoccipital, which is also relatively large, lacks any form of sculpturing, is trans- versely convex and bounded on either side by the parietals and by a posterior extension of the frontals. All these surrounding bones overlap its margin. Posteriorly, contact is made with the exoccipitals, and the supraoccipital contributes to the rim of the foramen magnum (Fig. ISbiii). MASTACEMBELOIDEI I: ANATOMICAL 45 The extrascapulae (both lateral and medial) and the posttemporal are absent. The flattened frontal lacks a descending lamina, crests, or any form of sculpturing. Anteriorly it has a relatively short, narrow region (dorsal to the small orbit), which overlies the lateral ethmoid; the longer posterior part is curved ventrolaterally. The parietal is small compared with this bone in Chaudhuria and other mastacembeloids. It has a narrow dorsal surface and a short posterolateral flange which lies along the dorsal junction between the epioccipital and exoccipital. A distinct notch in the posteromedial edge of the parietal forms, with the supraoccipital, a small opening in the posterior surface of the neurocranium (Fig. 1 5biii). Only short branches of the cephalic sensory canal system occur in the preoperculum, den- tary, frontal, 1 st infraorbital and nasal bones, and are presumably inter-connected by dermal branches. Jaws The single upper jaw element has been described by Yazdani (\916a & b; 1978). This element appears from its shape to incorporate the premaxilla with the maxilla, and may well have formed during ontogeny by the fusion of these bones (see discussion on p. 37, Fig. 16b). A short flange on the anteromedial face of the upper jaw bone articulates with the faceted anterior end of the vomer. The ventral surface is alveolate and bears an outer row of long caniniform teeth, and 1 to 2 inner rows of small teeth, decreasing in size posteriorly. Each dentary is joined to its partner in a symphysis lying in the vertical below the upper jaw symphysis. A short symphysial process descends from the anteroventral edge of the den- tary. The coronoid region is developed into a relatively tall, shallow process and is covered laterally by the posteroventral limb of the upper jaw. The alveolar surface along the dorsal edge (anterior to the coronoid process), bears an outer row of large caniniform teeth, relative to the size of the jaw, and 2 to 3 inner rows of smaller teeth. The posteroventral arm extends as a long pointed process along the ventral edge of the anguloarticular. A short sensory canal lies within the dentary which is pierced by three pores. The anguloarticular is a long tapered bone (Fig. 1 6b), and has a straight dorsal edge apart from a low projection anterior to the deep facet on the posterodorsal corner. Meckel's cartilage is long, rod-like, and passes along the medial face into the dentary. The retroarticular is small and roughly L-shaped with a very short lower arm (Fig. 16b). Except for its dorsal connection the retroarticular is free from the posteromedial face of the anguloarticular. The interopercular ligament is connected to the free posteroventral edge. The small coronomeckelian is similar to that in Chaudhuria (Fig. 16). Hyopalatine arch The hyomandibular shaft is short; a wide flange situated on its anterolateral face is connected anteriorly to the metapterygoid, and ventrally to the dorsal edge of the symplectic in an arrangement that corresponds closely to that seen in Chaudhuria (Fig. 1 7a & b). The long symplectic has a narrow lateral face and no dorsal lamina. Its anterior end lies below the posteromedial face of the quadrate. The metapterygoid has a small anterodorsal projection which, together with the bone's anterior edge, is separated from the quadrate by a cartilaginous interface. The quadrate has a straight anterior edge which ventrally forms a stout condyle for articulation with the anguloarticular facet. The endopterygoid is absent. The long ectopterygoid has a narrow lateral face and only its posterolateral margin lies medial to the anterodorsal corner of the quadrate (Fig. 17b). The anterior end is curved anteromedially and its medial face is loosely joined by connective tissue to the vomerine shaft. This connection is the anterior point of articulation between the suspensorium and neurocranium. The palatine is absent. It may be incorporated into the anterior arm of the ectopterygoid, 46 R. A. TRAVERS possibly by fusion, during ontogeny. The lack of direct articulation between the ectoptery- goid and lateral ethmoid, and the absence of a palatine, were not recognised by Yazdani (1976^:168) who described: narrow palatines '. . . movably united to parasphenoid and vomer' and the '. . . pterygoid (ectopterygoid) movably united to lateral ethmoid outside the palatine'. Opercular series The preoperculum lacks distinct vertical and horizontal arms (Fig. 18b), and is thus crescentic in shape. The lateral face of the preoperculum is wide and accommodates a short, indistinct sensory canal (as discussed above). The interoperculum, suboperculum and operculum are generally poorly ossified (Fig. 1 7b) and are arranged as in Chaudhuria (p. 38). Hyoid and branchial arches The basihyal is straight with a low ventral ridge. Posteriorly it overlies the anterior tip of basibranchial I (Fig. 20bi). The paired dorsal and ventral hypohyal bones, the anterior and posterior ceratohyals and the interhyal, closely correspond with the same elements in Chaudhuria (see above, p. 39 and Fig. 19a&b). The urohyal is forked anteriorly, posterior to this point a low ridge ascends from the dorsal surface ventral to basibranchial 2. The posterodorsal corner of the ridge is connected by a diverging ligament to the anterior tips of each hypobranchial 3. Basibranchial I lacks a ventral keel. Basibranchial 2 is narrow-waisted and lacks ventral processes. Basibranchial 3 is particularly long and tapered posteriorly; its cartilaginous tip lies ventral to basibranchial 4 (Fig. 20bi). This rod-like region is capable of sliding below basibranchial 4 when the branchial arches contract. Basibranchial 4 is a rhomboidal cartilaginous element (Fig. 20bi). Its anterolateral wall is connected to the medial edge of hypobranchial 3, and its posterolateral wall to the medial end of ceratobranchial 4. Hypobranchial 1 and 2 are cylindrical apart from a slight prominence along the anterior margin. Hypobranchial 3 is a small bone with a distinct, long and tapered anterior process which terminates below hypobranchial 2 (Fig. 20bi). The tip of this process is connected ligamen- tously to the posterior edge of the low ridge on the urohyal. The hypobranchial 3 toothplate is absent. Ceratobranchials 1-5 are rod-like elements and with the exception of the 5th are essen- tially alike. The dorsal surface of ceratobranchial 5 supports a narrow, fused toothplate bearing relatively large caniniform teeth. Posterior to its toothplate, ceratobranchial 5 curves dorsally into a relatively long process for muscle attachment (Fig. 20bi). All the dorsal gill arch elements lie posterior to the neurocranium and are essentially similar to those found in Chaudhuria (Fig. 20aii). Pectoral girdle The pectoral girdle lacks a bony connection to the neurocranium and lies posterior to the skull, adjacent to the 3rd and 4th abdominal vertebrae. Posttemporal sensory canal tubules are absent. The supracleithrum is small (Fig. 21bi) and accommodates a section of the postcranial sensory canal in its dorsolateral face. The cleithrum is a stout bone relative to the size of the other pectoral elements, is bowed and meets its partner in a ventral symphysis. The dorsal end is pointed and its posterior edge deeply grooved (Fig. 2 1 bi). MASTACEMBELOIDEI I: ANATOMICAL 47 ai an ENS HHAVt(1) bn ENS Prz Poz NAF HHAVt(1) EcR Fig. 21 Postcranial skeleton in (a) Chaudhuria caudata and (b) Pillaia indica; lateral view (left side) of pectoral girdle (ai & bi) and anterior abdominal vertebrae (aii & bii). 48 R. A. TRAVERS The remaining pectoral elements are small, ill-defined and cartilaginous. The fin rays do not appear to have differentiated in the specimens I examined, but Yazdani (1978) records 6 rays in the pectoral fin. Vertebral column The total vertebral count is 66, viz., 28 abdominal, 37 caudal and the fused ural and first preural centra. The first two abdominal vertebrae have compressed neural spines; that on the 1st has a serrated dorsal peak. The neural arches of these vertebrae have a perforated dorsolateral sur- face; anteroventral to the neural spine, a large foramen pierces the lateral face of the neural arch on all but the first 3 abdominal vertebrae. The anterior end of the 1st abdominal cen- trum is rounded to form a hemispherical condyle that articulates with the tripartite occipital socket in a 'ball and socket' joint. Pre- and postzygapophyses are well developed on all but the 1st abdominal vertebra which also lacks a well developed parapophysis. Laterally directed parapophyses occur on the 2nd, 3rd and 4th vertebrae but on the 5th they are curved ventrally, becoming increasingly so on all succeeding abdominal vertebrae. Along the abdominal vertebrae there is a total of 1 pair of epicentral and 24 pairs of pleural ribs. The pair of epicentral ribs occurs on the 1 st vertebra (Fig. 2 1 bii). This vertebra lacks lateral parapophyses and the anterior end of each rib is lodged in a recess within the posterolateral margin of the centrum, ventral to the postzygapophysis. The rib extends posteriorly to a point beyond the 2nd vertebra and its tip is connected by a short ligament to the dorsomedial face of the cleithrum. Pleural ribs are present on the 5th and all succeeding abdominal vertebrae. They are supported in a groove along the posterior face of the lateral parapophyses (Fig. 21bii). The caudal vertebrae have short, narrow neural and haemal spines and on some of the posterior vertebrae the spines have forked tips. A deep notch in the dorsolateral margin of the neural arches (Fig. 22, anterolateral to the neural spines) appears to have developed by the expansion of a foramen seen in the neural arches from the more posterior abdominal vertebrae. The asymmetry of the abdominal and caudal centra is gradually lost posteriorly. Dorsal and anal fins Dorsal and anal spinous rays and their supporting pterygiophores are absent. The dorsal and anal branched fin rays are composed of 35 and 36 segmented elements respectively. They extend, from a point above and below the abdominal/caudal vertebral junction, to the dorsal and ventral edge of the caudal fin, with which they are confluent. Each ray is supported by a pterygiophore system composed of 3 elements (Fig. 22). The proximal pterygiophore is a long, well-ossified element. Its distal end is fused to a medial pterygiophore. The rod-like medial pterygiophore is cartilaginous and lies anterior to the small, independent and ossified distal pterygiophore. Caudal fin The caudal fin is composed of 10 segmented fin rays which, although confluent with the posterior rays of the dorsal and anal fins, extend posteriorly well beyond their tips. Two hypural bones fan out from the fused ural and first preural centrum (Fig. 23b), these probably represent the fused lst + 2nd & 3rd + 4th + 5th + 6th hypurals found in more primi- tive teleosts. The elements each support 5 fin rays along their cartilaginous posterior margin. A small parhypural is sutured along the ventral edge of the hypaxial hypural. The epaxial hypural, the ural and first preural centra are fused into a single element (Fig. 23b). MASTACEMBELOIDEI I: ANATOMICAL 49 The uroneural is fused along the dorsal edge of the fused ural and first preural centra. There is only a single short epural which has a barbed, leading edge. The 2nd preural vertebra has fused neural and haemal arches. The corresponding spines are short and do not support fin rays. The tip of the haemal spine is forked as it is on the 3rd, 4th and 6th preural vertebrae. The neural spines are forked on the 5th and 6th preural vertebrae. Squamation The body is entirely scaleless. DDR PMPt -_HS PR CVt1 Fig. 22 Pillaia indica, abdominal/caudal vertebral junction and associated dorsal and anal fin rays: lateral aspect, left side. Comparative osteology of the Mastacembeloidei The osteological descriptions of Mastacembelus mastacembelus, Chaudhuria caudata and Pillaia indica are used here as the basis for a comparative osteological study of all available mastacembeloid species (see list of study material, Table 3). Each major osteological func- tional unit within a species is compared with its condition in M. mastacembelus in order to identify interspecific differences and similarities. Whether these character states are apomorphic or plesiomorphic for the group as a whole, or for any sublineage, and thus their value as indicators of phylogenetic relationships is considered in the sequal to this study (Travers, 1984). 50 R. A. TRAVERS DPt PU+U E DPMR PCR APR PU2 DPMR DDPt NAP +H PU2 Fig. 23 Posterior caudal vertebrae, associated fin rays and caudal fin skeleton in (a) Chaudhuria caudata and (b) Pillaia indica; lateral view, left side. Neurocranium Ethmovomerine region The condition of the ethmovomerine region in Mastacembelus mastacembelus (Fig. la) is typical of that found in most mastacembeloids. The posterolateral face of the supraethmoid septum is pierced by a fenestra in M. longicauda and M. reticulatus from West Africa (Fig. 33). A similar fenestra is also found in M. sclateri (Fig. 33d), although in this species it notches the posterodorsal edge of the supraethmoid. The fenestra is generally covered by a membrane and serves as the site of origin for the oblique eye muscles. Vomerine teeth were recorded by Regan (1912) although they are absent in all specimens I examined; Regan may well have misidentified the small toothplate that sometimes occurs on the anteroventral surface of the palatine. The near tubular lateral ethmoid is characteristic of both Asian, including the Middle Eastern, and African species. The centre of the lateral ethmoid in Mastacembelus marchii is subdivided by a median partition into two distinct tube-like canals. The ventral edge of the posterior opening in the lateral ethmoid in M. maculatus (Fig. 26a) is curved posteroventrally as it is in the West African species M. goro, M. greshoffi, MASTACEMBELOIDEI I: ANATOMICAL 51 N LE Sue FDL Pt Sph PP So Par Ex PPP ExDP Fig. 24 Mastacembelus sinensis, neurocranium in (a) lateral view, left side, (b) ventral view and (c) dorsal view. M. longicauda, M. loennbergii and M. niger. This ventral projection lies along the dorsal edge of the cartilaginous posterior end of the supraethmoid. The dorsal surface is grooved longitudinally to accommodate the anterior end of the large nervus olfactorius (p. 13) and the tip may contact the pterosphenoid (e.g. M. maculatus Fig. 26a). Orbital region In a number of taxa the morphology of the orbital region departs considerably from that of M. mastacembelus. The pterosphenoid, which generally forms a part of the anterolateral wall to the cranial cavity, is absent in Chaudhuria (Fig. 15ai) and Pillaia (Fig. 15bi). It is small in 52 R. A. TRAVERS a N LE Sue Sph So PalS PalSF TF SoC Fig. 25 Mastacembelus erythrotaenia, neurocranium in (a) lateral view, left side, (b) ventral view and (c) dorsal view. MASTACEMBELOIDEI I: ANATOMICAL 53 Mastacembelus aviceps (Fig. 40 a & b), a microphthalmic species from the lower Zairean rapids (Roberts & Stewart, 1976), and is discernible only as a splint-like bone sutured to the ventrolateral edge of the frontal. The posterior and anterior connections of the pterosphenoid may also differ from those in M. mastacembelus (p. 14). Posteriorly, it does not contribute to the rim of the trigeminal foramen in a number of species both among the Asian (e.g. M. erythrotaenia, Fig. 25a) and African (e.g. M.frenatus, Fig. 3 la) taxa; in these the anterior rim of the trigeminal foramen is formed by the prootic and sphenotic. The anterior edge of the pterosphenoid is partly restricted from bordering the postorbital edge of the neurocranium in four African species; M. micropectus (from Lake Tanganyika), M. stappersii (from Zaire), M. goro and M. batesii (from Cameroon). In these species the descending frontal lamina is particularly large and curves ventromedially, contacting its partner in the midline. The optic foramen in these species is predominantly enclosed by the frontals. A basisphenoid is present in almost all mastacembeloids, (pace Regan, 1912; Bhargava, 1963a; and Maheshwari, 19650), although it may be obscured in lateral view by the prootic, pterosphenoid and parasphenoid (Taverne, 1980). A large basisphenoid (relative to that in M. mastacembelus] occurs in Macrognathus species (M. siamensis, M. aral, and M. aculeatus), and to a lesser extent in Mastacembelus zebrinus among the Asian species and M. shiranus, M. congicus, M. liberiensis, M. longicauda and M. loennbergii among the African species. In these fishes the dorsal tip of the basisphenoid bridges the ventromedial edge of each pterosphenoid, which is incompletely sutured in the midline. A relatively large basisphenoid is associated with a greater distance between the pterosphenoid and paras- phenoid bones, and consequently with a less depressed orbital region than that in M. mastacembelus (Fig. la) or in other species with a small basisphenoid. The posterior edge of the large basisphenoid in M. shiranus, M. congicus, M. liberiensis, M. longicauda and M. loennbergii contributes, with the pterosphenoid, parasphenoid and anterior process of the prootic, to the formation of a large lateral foramen in the anteroventral wall of the neurocranium (Figs. 32a & 33a). This forms an unusually wide opening to the posterior myodome which in other species is generally a small foramen obscured, in lateral view, by the prootic. In Macrognathus aculeatus (Fig. 30a) and Mastacembelus zebrinus (Fig. 27a) the basisphenoid is particularly large and consequently there is a characteristically wide opening to the posterior myodome. The basisphenoid is absent only in Chaudhuria and Pillaia among the Asian, and Mastacembelus brichardi, M. crassus and M. aviceps among the African taxa (Figs. 39a & 40a: possibly M. latens should be included here as well). The general arrangement of the parasphenoid described in Mastacembelus mastacembe- lus (p. 14) is found in the majority of mastacembeloid taxa. However, there is interspecific variation in the posterior region of this bone. In Chaudhuria and Pillaia, and to a lesser extent in Mastacembelus sinensis (Fig. 24b), the posterior parasphenoid processes are par- ticularly long and narrow. They are distinguished in Chaudhuria and Pillaia at a point below the medial connection between the prootics (slightly posterior to this point in M. sinensis), and extend posteriorly as long, pointed processes to the posterior edge of the basioccipital. The posterior region of the parasphenoid in the Macrognathus species, and in Mastacem- belus pancalus and M. zebrinus (Figs 27 & 28) stands in marked contrast to that in Chaudhuria and Pillaia. Except for its posterior tip, the parasphenoid is undivided, and its ventral surface is excavated into the form of a 'blind' pit from which the posterior portion of the large adductor hyomandibulae muscles originate. The cavity is particularly deep in M. zebrinus and M. pancalus. These species also differ in having a deep ventral ridge on the parasphenoid. This ridge lies medially along the posteroventral surface of the bone and divides the pit-like cavity; it is deepest in M. zebrinus. The two ascending processes on the posterodorsal edge of the 1st infraorbital bone (Fig. 3) are generally well-developed in all species. The posterior process articulates syndesmoti- cally with the lateral ethmoid and may protrude posterodorsally in some species (Fig. 4 la) 54 a Sue N LEVP R. A. TRAVERS F FDL Sph So Par Pal Bs Bo 0PM Fig. 26 Mastacembelus maculatus neurocranium in (a) lateral view left side, (b) ventral view and (c) dorsal view. in association with the anterior expansion of the adductor arcus palatini muscle (discussed below p. 126). The shorter, anterior ascending process is absent in Mastacembelus sinensis, Chaudhuria and Pillaia. In these taxa, anterior to the posterior nasal opening the dorsal edge of the 1st infraorbital is straight and is connected by the integument to the nasal. The posteroventral process or preorbital spine on the 1 st infraorbital varies in its degree of development. A preorbital spine (similar to that described in M. mastacembelus p. 16), occurs in the Sue MASTACEMBELOIDEI I: ANATOMICAL LE F FDL 55 Ft Sph Pa- Pal EC PrAP Bo OPM PPS BLF Fig. 27 Mastacembelus zebrinus, neurocranium in (a) lateral view, left side, (b) ventral view and (c) dorsal view. majority of Asian species, it is absent in Chaudhuria (Fig. 1 5aiii) and Pillaia (Fig. 1 5biii) and is represented by a short posterior projection in Macrognathus (Fig. 4 la). A spine is also well-developed in the majority of African mastacembeloids. In a number of species, however, (e.g. Mastacembelus albomaculatus, Fig. 41b) the spine is present only as a slight projection on the posteroventral edge of the 1 st infraorbital and in others it is absent (e.g. Mastacembelus aviceps and M. ophidium, Fig. 41c & d). Intraspecific variation in the morphology of the preorbital spine in Mastacembelus moorii has been discussed by Matthes (1962: 73). He found a sequential development from a prominent spine in a juvenile 56 a Sue R. A. TRAVERS FDL Bs Par So ExVE Bo BLF PPS Fig. 28 Mastacembelus pancalus, neurocranium in (a) lateral view, left side, (b) ventral view and (c) dorsal view. specimen (100mm. long) to a much broader flange with only a slight projection on the posterodorsal corner in an adult specimen (410 mm. long). If a prominent 1st infraorbital spine is absent in the adult, it was not found in pre-adult specimens of any species examined. The remaining infraorbital bones are reduced to ossifications around the sensory canal. The extent to which the canal is ossified shows interspecific variation. In some African species MASTACEMBELOIDEI I: ANATOMICAL 57 Sue PtN Sph So Par Bs BLF Fig. 29 Macrognathus siamensis, neurocranium in (a) lateral view, left side, (b) ventral view and (c) dorsal view. (e.g. Mastacembelus cunningtoni, and M.frenatus) the canal is ossified along its entire length, and there are five infraorbital tubules, as in M. mastacembelus (p. 16). In contrast some taxa from Asia (e.g. Chaudhuria and Pillaid) and from Africa (e.g. Mastacembelus brichardi) have only the 1st element ossified. Between these extremes there is a series, incorporating the majority of mastacembeloid taxa, in which 1, 2, 3 or 4 tubules are ossified. Otic region The bones of the otic region show considerable interspecific variation in their morphology and will be considered individually. 58 a Sue R. A. TRAVERS FD!- pt sph Pal Fn ExVE OPM LCF TF FF BLF Fig. 30 Macrognathus aculeatus, neurocranium in (a) lateral view, left side, (b) ventral view and (c) dorsal view. The otic region in all mastacembeloids is dominated by a particularly large prootic which, together with the sphenotic, pterosphenoid and descending frontal lamina forms the excep- tionally long precommissural lateral wall of the neurocranium. The prootic is a long bone with a prominent anterior process in Asian and African species, although among the latter, there are 5 species which do not have the prootic developed to an extent comparable with MASTACEMBELOIDEI I: ANATOMICAL 59 Sue N LE FDL Pt Sph Par PrAP FDL StSC Fig. 31 Mastacembelus frenatus, neurocranium in (a) lateral view, left side and (b) dorsal view, and Mastacembelus shir anus, otic region (c) in lateral view, right side. that of M. mastacembelus. In Mastacembelus micropectus, M. brichardi (Fig. 38a) and M. longicauda (Fig. 33a) the anterior prootic process extends only halfway across the lateral face of the pterosphenoid. The condition in Mastacembelus crassus and M. aviceps (Figs 38a & 40a) is even more extremely modified. In these two crypto- and microphthalmic species the prootic anterior process is poorly developed, particularly in Mastacembelus aviceps, and extends only slightly anterior to the trigeminal foramen, this region of the neurocranium having a tubular shape. 60 a R. A. TRAVERS Sue So Ran EC PrAP Bs OPM Bo Dpto Fig. 32 Mastacembelus congicus, neurocranium in (a) lateral view, left side and (b) dorsal view. Tubular neurocrania have been associated by Rosen & Greenwood (1976: 45) with eye reduction. Among the Asian mastacembeloids, including those of the Middle East, Pillaia is the only taxon lacking a distinct anterior process on the prootic (Fig. 15bi). In Pillaia, as in Mastacembelus aviceps, the prootic does not extend anteriorly beyond the trigeminal foramen, and its overall tubular neurocranium can probably be correlated with its eye reduction. In contrast to the arrangement in M. mastacembelus (Fig. la), the tip of the anterior process on the prootic in some species is curved anterodorsally and contacts a pedicel on the frontal and/or pterosphenoid. In these species the prootic bridges the nerves and blood vessels that emerge from the trigeminal foramen. A prootic bridge of this type was only found in 6 African taxa, viz., Mastacembelus albomaculatus, M. moorii, M. plagiostomus and M. tanganicae, all endemic to Lake Tanganyika, in M. paucispinis from the lower Zairean rapids, and in an undescribed Mastacembelus species recently collected by T. Roberts (pers. comm.) from the Cross River rapids in Cameroon. The tip of the anterior process on the prootic is curved dorsally in M. paucispinis and M. moorii (Fig. 35 a & d) and contacts a wide pedicel on the lateral face of the descending frontal lamina. The truncus supraorbitalis and the internal jugular vein pass medial to the connection between these elements. A similar arrangement occurs in the undescribed species MASTACEMBELOIDEI I: ANATOMICAL 61 Sue N Fn LE FDL Pt Sph So Par PalT EC OPM SB Sue Sue Fig. 33 Mastacembelus longicauda, neurocranium in (a) lateral view, left side, and (b) dorsal view, and Mastacembelus reticulatus (c), and Mastacembelus sclateri (d), ethmoid region in lateral view, left side. (Fig. 36a). In that species the elements are not in direct contact but are joined by a short ligament. The tip of the anterior process on the prootic in M. albomaculatus and M. plagiostomus (Fig. 35c & 0 forms a similar bridge across the anterolateral wall of the neurocranium by contacting a small pedicel on the pterosphenoid. In M. tanganicae (Fig. 62 Sue So F FDL Pt Sph Dpto P&IT EC Bo Fig. 34 Mastacembelus nigromarginatus, neurocranium in (a) lateral view, left side and (b) dorsal view. 35g) a bridge is present but results from the tip of the anterior process on the prootic curving posterodorsally to lie across the frontal/pterosphenoid lateral border. Some variability found in the bridge of one specimen of M. moorii and one of M. paucispinis is not thought to represent significant intraspecific variation since the incomplete bridge on one side of the neurocranium in both these specimens appears to be the result of incomplete ossification at the tip of the anterior prootic process. The tip of the anterior process is shaped like a hockey stick in the Zairean species Mastacembelus ubangensis, in M. congicus (Fig. 32a), and in the widely distributed M. Jrenatus (Fig. 3 la). In these species the broad, slightly upturned tip of the prootic lies below a horizontal region on the ventral edge of the descending frontal lamina. A long ligament connecting the elements to form a bridge across the truncus supraorbitalis and the internal jugular vein, may be interpreted as an intermediate stage in the development of the bridge found, for example, in M. paucispinis. A horizontal shelf-like ridge lies, longitudinally along the prootic, with its dorsal surface sloping ventrally, in 5 African species; Mastacembelus moorii and M. zebratus from Lake Tanganyika, M. stappersii from Zaire, M. vanderwaali from southern Africa (Skelton, 1976), and M. sclateri from Equatorial Guinea. A prootic 'shelf is best developed in M. sclateri (Fig. 42a). Here, and to a lesser extent in M. stappersii (Fig. 42b), it is continuous with the lower edge of a groove in the ventrolateral face of the pterosphenoid. In M. vanderwaali the 'shelf is in the form of a narrow ridge on the anterolateral face of the prootic and may represent a less derived condition than that described above. It MASTACEMBELOIDEI I: ANATOMICAL 63 resembles the ridge on the anterolateral face of the prootic in M. mastacembelus (Fig. la, p. 1 7). Mastacembelus moorii has a short, horizontal 'shelf on the midlateral face of the prootic. The lateral edge of this 'shelf is inclined dorsally, giving it an up-turned edge affording greater support for the truncus supraorbitalis nerve and the internal jugular vein which pass longitudinally along its dorsal surface. Sue Par So PrAP Bo PalT Fig. 35 a-c Mastacembelus paucispinis neurocranium. See p. 64 for full caption. SphAF FP PrAP SphAF 9 Sph Pt FDL PrAP PrAP Fig. 35 Mastacembelus paucispinis, neurocranium in (a) lateral view, left side, (b) ventral view and (c) dorsal view. Also shown in lateral view is the pre-otic region in (d) Mastacembelus moorii and (e) Mastacembelus albomaculatus (left side), and (f) Mastacembelus plagiostomus and (g) Mastacembelus tanganicae (right side). See p. 63 for a-c. A fenestra between the anterior process and the trigeminofacialis chamber pierces the lateral face of the prootic in the Macrognathus species (Figs 29a & 30a) and appears to be covered by a thin membrane. The trigeminal foramen shows little interspecific variation in either its overall size or its position in the lateral wall of the neurocranium. However, the prootic spur which forms the anterior rim of the trigeminal foramen in M. mastacembelus (Fig. la) varies interspecifi- cally in size and shape. When present, the tip of this spur may contact the ventral tip of a similar descending sphenotic spur in some Asian (e.g. Mastacembelus armatus) and African, (e.g. Mastacembelus moorii) mastacembeloids. In this condition, the posterior edge of the spur forms the anterior rim of the trigeminal foramen. The tips of the prootic and sphenotic spurs in other species (e.g. Mastacembelus mastacembelus and M. vanderwaali) do not always contact each other; instead, the posterior edge of the pterosphenoid is intercalated between their tips and thus contributes to the rim of the trigeminal foramen. The ascending prootic spur in Mastacembelus frenatus (Fig. 3 la) and in M. shiranus (from Lake Malawi, Fig. 31c) is particularly well-developed. In these species the tip is expanded, giving it in lateral view the shape of a cobbler's last. Apart from M. frenatus, M. moorii and M. ophidium, all Tanganyikan species lack a prootic ascending spur. This is also true of M brichardi, M. aviceps and M. brachyrhinus from the Zairean rapids and M. liberiensis, M. loennbergii, M. longicauda and M. sclateri from Western Africa. In all African and Asian MASTACEMBELOIDEI I: ANATOMICAL 65 Sue N, FDL Sph So Par Fig. 36 Neurocranium of an undescribed Mastacembelus species in (a) lateral view, left side, (b) ventral view and (c) dorsal view. species lacking a prootic ascending spur, the posterior edge of the pterosphenoid forms the anterior margin of the trigeminal foramen. The prootic spur in Macrognathus siamensis (Fig. 29a) and Macrognathus aral is small. The posterolateral margin of the pterosphenoid is deeply notched in these species, and forms the anterior region of the trigeminal foramen. 66 R. A. TRAVERS a Sue EC Pt SPh ppto p^ So Bs Bo Exsc Fig. 37 Mastacembelus brachyrhinus, neurocranium in (a) lateral view, left side, (b) ventral view and (c) dorsal view. a MASTACEMBELOIDEI I: ANATOMICAL Sue N LE Pt SphAF Par So PrAP Ep 67 Pr Fig. 38 Neurocranium of Mastacembelus brichardi in (a) lateral view, left side, (b) ventral view, (c) dorsal view; and of Mastacembelus micropectus (d) lateral view, left side. The facial foramen in Mastacembelus longicauda (Fig. 33a) is unusually large and is con- nected, via a narrow opening, to the posterior margin of the trigeminal foramen. Chaudhuria, (Fig. 15ai), Pillaia (Fig. 15bi) and Mastacembelus crassus (Fig. 39a) lack separate trigeminal and facial foramina, and have a single large foramen in the trigeminofacialis chamber. An 68 R. A. TRAVERS a Sue N F FDL SphAF So Par Pal Apto Bo Ex stsc Fig. 39 Mastacembelus crassus, neurocranium in (a) lateral view, left side, (b) ventral view and (c) dorsal view. even more extreme condition is found in M. aviceps where, due to the open postorbital lateral wall of the neurocranium, there are no foramina (Fig. 40a). Interspecific variation in the size and position of the lateral commissure is slight apart from the development of an anterodorsal flange in some taxa. A flange on the anterodorsal face of the lateral commissure in Macrognathus is developed to an increasing degree in M. MASTACEMBELOIDEI I: ANATOMICAL 69 siamensis (Fig. 29a), M. aral and M. aculeatus. In M. ami and M. aculeatus it extends anterolaterally to such an extent that in its most extreme condition (i.e. M. aculeatus Fig. 30a) it lies above the upper edge of the trigeminal foramen, and is sutured to the entire, precommissural ventral edge of the sphenotic. A small sacculus lodged in the posteromedial face of the prootic (Fig. 1 a & b) is character- istic of most taxa. The bulla accommodating the sacculus in M. brichardi (Fig. 38 a & b), M. crassus (Fig. 39a & b) and M. aviceps (Fig. 40 a & b) is particularly large relative to the recess in M. mastacembelus. However, this otolith recess, regardless of its size, is accommodated entirely within the prootic in these species, as it is in the majority of masta- cembeloids examined. A large bulla also occurs in Mastacembelus micropectus (Fig. 38d), Chaudhuria (Fig. 1 5ai & ii) and Pillaia (Fig. 1 5bi & ii). In these taxa, however, it is not lodged entirely in the prootic, but lies partly in the prootic, exoccipital and basioccipital bones. There is little interspecific variation in the morphology of the sphenotic. A prominent anterolateral flange occurs in all taxa. This extension of the sphenotic, and the posterior position of its postorbital process, may be correlated with the long precommissural region of the neurocranium. The anterior edge of the sphenotic is sutured to the posterior edge of the frontal lamina (by which it is excluded from the postorbital border of the orbit) in most mastacembeloids. In Chaudhuria (Fig. 15ai) and Pillaia (Fig. 15bi) the anterior region is attenuated and, since the descending frontal lamina is absent, the tip passes to the posterior margin of the orbit. A similar condition occurs in M. aviceps (Fig. 40a) which also lacks a descending frontal lamina although in this species the sphenotic is shorter and does not extend anteriorly to the margin of the orbit. This arrangement is associated with the extreme precommissural attenuation of other neurocranial bones and a reduction in eye size. The postorbital process on the sphenotic is developed to a varying extent. It is particularly large in the Tanganyikan species Mastacembelus moorii and M. ophidium, and in the west African species M. goro and M. longicauda (Fig. 33). In Mastacembelus shiranus the process is short, and it is absent in M. vanderwaali. When present this process serves as a point of insertion for the levator arcus palatini muscle (p. 1 19). A ventrolateral 'wing' of the sphenotic occurs in Mastacembelus congicus, M. niger, M. marmoratus, M. ubangensis, M. vanderwaali, M. goro, M. sclateri and M. nigromarginatus (from Ghana; Fig. 34) and M. reticulatus (from Sierra Leone). It is particularly well developed in M. congicus (Fig. 32a) and overlies the trigeminal foramen to a greater extent than in any other species. A small descending spur, like the prootic spur described above, on the ventral edge of the sphenotic occurs mosaically among the Asian and African species. The most significant interspecific variation in the morphology of the pterotic occurs in a single Zairean species — Mastacembelus brachyrhinus (Fig. 37a & c). The dorsal (dermopterotic) part of the pterotic in this species is enlarged in comparison with its con- dition in M. mastacembelus (Fig. la & c), which latter condition represents the more usual mastacembeloid arrangement. The enlarged dorsal region of the pterotic in M. brachyrhinus is combined with a posterodorsal expansion of the frontal. The condition of the epioccipital in M. mastacembelus (Fig. Ic) reflects the arrangement of this bone in both Asian and African mastacembeloids. The exoccipital varies interspecifically in a number of features. Its dorsomedial process, as described in M. mastacembelus (p. 18), is not connected to its partner in Mastacembelus sinensis (Fig. 24c), Chaudhuria (Fig. 1 5aiii) or in Pillaia (Fig. 1 5biii). In these species the posterodorsal edge of the supraoccipital lies between the dorsomedial face of each exoccipi- tal. The foramen magnum is not, therefore, surrounded by the exoccipitals alone but by the posterior edge of the supraoccipital as well. A further characteristic of the exoccipital in these three taxa is its perforated dorsal surface. The ventrolateral face of the exoccipital is expanded in taxa with a deep basicranium (p. 53). In these, which include Mastacembelus pancalus (most extreme basicranial expansion), Mastacembelus zebrinus and to a lesser extent Macrognathus, the lateral wall of the 70 R. A. TRAVERS a Sue N Par Ep Apto Pal EC Fig. 40 Mastacembelus aviceps, neurocranium in (a) lateral view, left side, (b) ventral view and (c) dorsal view. exoccipital is expanded ventrally and thus contributes to the deepening of the basicranium. The basioccipital also contributes to the overall increase in depth of the basicranium in M. pancalus, M. zebrinus and in Macro gnathus species. The expanded basioccipital in M. pancalus extends posteroventrally below the cranio- vertebral joint. The fossa for Baudelot's ligament is particularly deep in M. pancalus (Fig. 28b), it lies on the posteroventral edge of the basioccipital, and has an ovoid opening. The fossa is in a similar position in M. zebrinus and all the Macrognathus species. MASTACEMBELOIDEI I: ANATOMICAL 71 AAPP loAP loPP Fig. 41 Lateral view of left 1 st infraorbital bone in (a) Macrognathus aculeatus, (b) Mastacembelus albomaculatus, (c) Mastacembelus aviceps and (d) Mastacembelus ophidium (right -side). A tripartite occipital facet, (p. 1 8) occurs in all mastacembeloids. There is little interspecific variation in the morphology of the supraoccipital, apart from the extent to which it contributes to the dorsal rim of the foramen magnum (discussed above). The supraoccipital is a comparatively small bone in M. sinensis (Fig. 24c) and may not contact the frontals anteriorly; as a result the anteromedial edge of the parietals contact medially. 72 R. A. TRAVERS The transverse channel that crosses the posterodorsal surface of the supraoccipital in M. mastacembelus (Fig. Ic) is absent in several Asian and African species. Among the Asian taxa, Mastacembelus pancalus (Fig. 28c), M. sinensis (Fig. 24c), Chaudhuria (Fig. 1 5aiii) and Pillaia (Fig. 15biii) all lack a channel; and it is also absent in Mastacembelus albomaculatus, M. cunningtoni, M.frenatus (Fig. 31c), M. plagiostomus, M. tanganicae, M. zebratus, M. shiranus, M. congicus (Fig. 32c), M. aviceps (Fig. 40c) and M ubangensis among the African species. The sensory canal commissure in these African species lies within the integument above the dorsal surface of the supraoccipital. A dermosupraoccipital, as described in Mastacembelus congicus by Taverne (1973), was not distinguished in any mastacembeloids examined, nor could I find any trace of the element Patterson (1977: 98) described as *. . . a plate-like median extrascapular which overlies the supraoccipital and may fuse with it in full grown individuals'. The transverse channel across the dorsal surface of the supraoccipital, which accommo- dates the supratemporal sensory canal commissure, is covered by a thin layer of bone in some species (e.g. Mastacembelus moorii) and presumably results from the supraoccipital enclosing this canal during ontogeny. The extrascapulae, both lateral and medial, are absent in all mastacembeloid taxa although my specimen of Mastacembelus brachyrhinus (Fig. 37c) is presumably exceptional as a left lateral extrascapula is clearly discernible. The frontal shows interspecific variation in the morphology of its dorsal surface and its vertical lamina. In M. mastacembelus (Fig. la) and a number of other Asian species (e.g. Mastacembelus erythrotaenia, Fig. 25c), and the majority of African species (e.g. Mastacem- belus frenatus, Fig. 3 1 c) the dorsal surface of the frontal is almost flat, with only the lateral edge curved ventrally. A group of Asian taxa including Mastacembelus pancalus, M. zebrinus and the Macrognathus species have a frontal with a strongly curved dorsal surface. In M. pancalus (Fig. 28a) the lateral edge of the frontal is curved ventrally to such an extent that, in transverse section, the highest point on the dorsal surface of the neurocranium is along the median connection of the frontals. A similar type of frontal morphology occurs in M. zebrinus and to a lesser extent in the Macrognathus species. Its curvature in these species gives the neurocranium a much deeper appearance than that of M. mastacembelus. A further consequence of a steeply sloping frontal is the relatively ventral position of the trigeminofacialis chamber. Such a condition may also be correlated with the marked basicranial expansion in these taxa (as described earlier p. 69). The dorsal surface of the frontal is curved to a varying degree in a number of other species (e.g. Mastacembelus brachyrhinus and M. brichardi), but no other Asian or African taxa exhibit the pronounced curvature of the frontal found in M. pancalus, M. zebrinus and in all Macrognathus species. The anterior region of the frontal, which roofs the orbit, is short in Mastacembelus brichardi (Fig. 38c), M. crassus (Fig. 39c) and M. aviceps (Fig. 40c), and is apparently associated with the small eyes of these rapids-dwelling species (see also p. 125). A descending vertical lamina on the frontal, as described in M. mastacembelus (p. 1 9) is a characteristic feature of all mastacembeloids apart from Chaudhuria (Fig. 1 5ai) and Pillaia (Fig. 1 5bi). The lack of a frontal lamina is one of many characters in the neuro- cranium of Chaudhuria and Pillaia that are possibly reductional. A comparatively low descending frontal lamina occurs in the highly derived taxa of the Zairean rapids, Mastacem- belus aviceps (Fig. 40a) and M. crassus (Fig. 39a). Variability in the size of the lamina and the presence of a pedicel on its lateral face have been discussed above (p. 60). There is little interspecific variation in the morphology of the parietal. The parietals in all Asian and African species apart from Chaudhuria (Fig. 1 5aiii) and Pillaia (Fig. 1 5biii) accommodate the supratemporal branch of the cephalic sensory canal system (Maheshwari, 1971), normally associated with the extrascapulae. A pore is present in the canal in all taxa except Chaudhuria and Pillaia. The medial connection between the parietals in Mastacem- belus sinensis (Fig. 24c) is unique to that species, and is directly related to the small dorsal area of the supraoccipital (p. 71). The relatively small dorsal surface area of the parietal in MASTACEMBELOIDEI I: ANATOMICAL Pt Sph 73 FDL PrSh Sph Fig. 42 Pre-otic region of neurocranium in (a) Mastacembelus sclateri and (b) Mastacembelus stappersii; lateral view, left side. Mastacembelus brachyrhinus (Fig. 37c), in association with the enlarged pterotic and posterior region of the frontal (p. 69), is a characteristic of the species. The absence ofaposttemporalbone is a characteristic feature of all taxa. The only remnant of this bone in M. mastacembelus is two ossified tubules which surround two sections of the postcranial sensory canal (p. 19). Interspecific variation in the number of posttemporal tubules among Asian and African species is summarised in Table 4. Tubules are completely absent in some Asian (including Mastacembelus armatus, M. sinensis, Chaudhuria and Pillaid) and African taxa (including Mastacembelus shiranus, M. congicus, M. brichardi, M. niger, M. sclateri and M. flavomarginatus). Intraspecific variation in the number of tubules 74 R. A. TRAVERS Table 4 Number of posttemporal tubules in mastacembeloid species. Absent 1 2 Oriental mastacembeloid taxa Mastacembelus armatus + Mastacembelus erythrotaenia + Mastacembelus maculatus + Mastacembelus mastacembelus + Mastacembelus pancalus + Mastacembelus sinensis + Mastacembelus unicolor + Mastacembelus zebrinus + Macrognathus aculeatus + Macrognathus siamensis + Chaudhuria caudata + Pillaia indica + African mastacembeloid taxa Mastacembelus albomaculatus + Mastacembelus aviceps + Mastacembelus batesii + Mastacembelus brachyrhinus + Mastacembelus brevicauda + Mastacembelus brichardi + Mastacembelus congicus + Mastacembelus crassus + Mastacembelus cunningtoni + Mastacembelus ellipsifer + Mastacembelus flavomarginatus + Mastacembelus frenatus + (L) Mastacembelus goro + Mastacembelus greshoffi + Mastacembelus liberiensis + Mastacembelus loennbergii + Mastacembelus longicauda + Mastacembelus marmoratus + Mastacembelus micropectus + Mastacembelus moorii + Mastacembelus niger + Mastacembelus nigromarginatus + Mastacembelus ophidium + (R) Mastacembelus paucispinis + Mastacembelus plagiostomus Mastacembelus platysoma + Mastacembelus reticulatus + (L) Mastacembelus sclateri + Mastacembelus shiranus + Mastacembelus stappersii + Mastacembelus tanganicae + Mastacembelus vanderwaali + Mastacembelus zebratus Mastacembelus sp. nov. + MASTACEMBELOIDEI I: ANATOMICAL 75 may also occur. For example, one side of the head in a specimen of M. frenatus and one of M. reticulatus, has three and the other side two tubules, while a specimen of M. ophidium has three tubules on the left and only one of the right side. Jaws Upper jaw There is little variation in the overall morphology of these bones. The most extreme variation occurs in Pillaia (Fig. 16b) where the upper jaw is formed from a single tooth bearing element. This bone was identified by Yazdani (1976a) as a premaxilla, and he suggested '. . . the posterior part of the upper jaw bone in Pillaia indica represents the maxilla which has fused with the premaxilla in the course of evolution . . .'. The jaws in the specimens of Pillaia examined confirm that a single bone is present, but, whether this is the result of fusion or the loss of the maxilla cannot be determined without ontogenetic evidence. The upper jaw arrangement in Mastacembelus aviceps, from the lower Zairean rapids, may help clarify this problem. The anterior half of the maxilla in M. aviceps (Fig. 44a) is reduced to an attentuated bony strand lying within a longitudinal groove on the dorsal sur- face of the premaxilla. Posteriorly, the maxilla is thickened and expanded ventrolaterally to a level below the premaxilla, with which bone it is tightly connected. These modifications in M. aviceps give its upper jaw a marked resemblance to that in Pillaia. This may be the result of a similar developmental trend in the two taxa, a trend which in Pillaia is at a more advanced stage and has involved the complete loss of the reduced anterior region of the maxilla and a fusion of the broader posterior flange to the premaxilla. The anterior region of the maxilla is expanded in Mastacembelus moorii (Fig. 43a) and M. ophidium (Fig. 43b) from Lake Tanganyika. In these species the anterior half of the maxilla is lateromedially compressed, giving it a wide anterolateral face which may function as a support for the exceptionally large and fleshy lips. The premaxillary dentition exhibits considerable variation in the size and number of teeth. Typically it consists of an outer row of large caniniform teeth followed by three of four inner rows which decrease in number and tooth size posteromedially, e.g. the Asian Mastacem- belus maculatus and M. armatus, and the African M. frenatus and M. goro. Teeth in the outer row are particularly large in Mastacembelus moorii and M. ophidium (Fig. 43a & b) and there are numerous inner rows of small teeth. The dentition in these taxa gives the premaxilla a characteristically wide alveolar surface, possibly related to their piscivorous diet. The alveolar surface on the premaxilla of a third Tanganyikan species, Mastacembelus cunningtoni (Fig. 45a) is wide, with up to eighteen irregular rows of small, slender teeth, each with a posteriorly curved tip. A broad alveolar surface on the premaxilla is also a feature of a number of Asian mastacembeloids, including Mastacembelus zebrinus, M. pancalus and the Macrognathus species (Fig. 46). In these taxa the rostral appendage is larger than in other mastacembeloids, and in M. pancalus (and to a lesser extent in M. zebrinus) the alveolar surface of the premaxilla is curved ventrorostrally around its buccal face. The under surface bears numerous, small, irregularly spaced caniniform teeth which tend to lie horizontally, their tips directed posteriorly. Anteriorly, the premaxillary alveolar surface contacts its partner in a symphysis anteroventral to the head of the vomer. Furthermore, the anterior tip of this tooth bearing surface has fragmented into a single plate on the right premaxilla in a specimen of M. pancalus (Fig. 45b). The fragmentation of the alveolar surface in Macrognathus species appears to represent a more advanced stage in the phylogenetic development of this character from its condition in Mastacembelus pancalus. The anterior end of the alveolar surface in Macrognathus has fragmented into a long series of laterally expanded, flexible dentigerous bony plates (Fig. 45c) which extend along the ventral surface of the rostral appendage and are tapered anteriorly. The smallest plate lies posteroventral to the anterior nostril and the tip of the rostrum. On the ventral surface of each pair of rostral plates is a transverse row of small caniniform teeth 76 R. A. TRAVERS Pal Com Fig. 43 Hyopalatine arch, preoperculum and jaw bones in (a) Mastacembelus moorii, (b) Mastacembelus ophidium and (c) Mastacembelus micropectus; lateral view, left side. MASTACEMBELOIDEI I: ANATOMICAL 77 Com Aa Ra Fig. 44 Hypolatine arch, preoperculum and jaw bones in (a) Mastacembelus aviceps (maxilla displaced dorsally), (b) Mastacembelus crassus, (c) Mastacembelus brichardi, lateral view, left side. with posteriorly directed tips. The toothed alveolar surface of the premaxillae forms a continuous series with the rostral toothbearing plates. In the opinion of Roberts (1980: 390) variation in the number of premaxillary rostral plates '. . . provides perhaps the most important character for distinguishing the species of 78 R. A. TRAVERS FPmAS MX Fig. 45 Upper jaw bones (ventral aspect) in (a) Mastacembelus cunningtoni, (b) Mastacembelus pancalus, and (c) Macrognathus aculeatus. Macrognathus'. The lowest number occurs in Macrognathus siamensis (usually between 9-12 pairs), the highest in Macrognathus aculeatus (usually between 38-55 pairs); inter- mediate between these species are the 14-28 pairs usually found in Macrognathus aral. The overall length of the rostral appendage in each of these species is directly proportional to the number of premaxillary plates present. MASTACEMBELOIDEI I: ANATOMICAL 79 Hyo End Met Sym Ect Com Aa FPmAS Fig. 46 Hyo-pterygoid arch, preoperculum and jaw bones in (a) Mastacembelus zebrinus, (b) Mastacembelus pancalus and (c) Macrognathus aculeatus; lateral aspect of left side. Associated with the enlargement and fragmentation of the toothbearing premaxillary alveolar surface in these taxa is the attenuation of the maxilla. In Mastacembelus zebrinus, M. pancalus and to a greater extent in the Macrognathus species, the maxilla has a long, weak anterior process and narrow posteroventral flange (Fig. 46a-c) compared to that of M. mastacembelus (Fig. 4) which represents the modal type. 80 R. A. TRAVERS Lower jaw Interspecific variation in the morphology of the lower jaw is mainly confined to the dentary and coronomeckelian. The dentary forms almost the entire ventral edge of the mandible in all taxa and in the majority of species its lateral face is pierced by four sensory canal pores. Three pores occur, among the Asian taxa, in Mastacembelus maculatus, M. pancalus and in the three Macrognathus species; among the African species three pores occur in Mastacembelus liberiensis, M. greshoffi, M. loennbergii and M. ubangensis. Dentary pores are reduced to three in Pillaia and are absent in Chaudhuria (as discussed above p. 36). The upper or coronoid process of the dentary has two forms, either tall and narrow or low and broad based. The process in M. mastacembelus (Fig. 4) is of the tall, narrow type, which also occurs in Mastacembelus erythrotaenia, M. sinensis, Chaudhuria and Pillaia among the Asian species examined, as well as in the majority of African species. A low, broad coronoid process occurs in most of the other Asian taxa examined including Mastacembelus zebrinus, M. pancalus and the Macrognathus species (see Fig. 46a), although the size and shape of the coronoid process in Mastacembelus armatus and M. maculatus appear to be intermediate between these types. A low, broad coronoid process also occurs in a number of African species including Mastacembelus cunningtoni, M. ellipsifer, M. moorii and M. platysoma from Lake Tanganyika, M. congicus, M. paucispinis and M. ubangensis from Zaire; M. sclateri from Sierra Leone, and in M. goro, M. liberiensis and M. niger from West Africa. Although the coronoid process in M. zebrinus, M. pancalus and the Macrognathus species is of a low, broad type similar to that in the African species listed above, it may be dis- tinguished by the posterior expansion of the toothbearing alveolar surface onto its medial face (Fig. 57c). A slight encroachment of the dentary toothplate onto the medial face of the coronoid process was only found in M. goro among the African taxa. The other lower jaw element in which considerable interspecific variation occurs is a sesamoid ossification considered to be the coronomeckelian. The size and position of the coronomeckelian is a diagnostic feature of all mastacembeloid taxa apart from Chaudhuria (Fig. 16a) and Pillaia (Fig. 16b). It does not lie dorsal to the anguloarticular in these taxa, but is a small ossicle attached to the posterodorsal edge of Meckel's cartilage, on the medial face of the anguloarticular. Variation in the overall length of the coronomeckelian is indicated by the position at which its posterior tip lies across the suspensorium. In the Zairean rapids species Mastacembelus brachyrhinus, M. brichardi, M. crassus and M. aviceps (Fig. 44a-c; and possibly M. latens), it is much shorter than the modal condition found, for example, in M. mastacembelus (Fig. 4). In species with a tall and narrow coronoid process the coronomeckelian extends dorso- caudally from the dorsomedial margin of the anguloarticular to lie above the anterior face of the ectopterygoid. Some African taxa have a much larger coronomeckelian in comparison with that of the rapids species described above and M. mastacembelus. These include M. cunningtoni, M. ellipsifer, M. moorii, and M. platysoma from Lake Tanganyika; M. congicus, M. paucispinis and M. ubangensis from Zaire; M. sclateri from Sierra Leone; M. liberiensis, M. goro and M. niger from West Africa. The coronomeckelian in these species extends well beyond the point occupied by the posterior tip of the bone in M. mastacembelus; for example, in M. cunningtoni the stout bone extends across the lateral faces of the ectopterygoid and quadraic to the latter's border with the metapterygoid. The coronomeckelian in M. ellipsifer, M. platysoma (in which it is barbed) and M. sclateri is of approximately equal extent to that in M. cunningtoni, while in M. congicus, M. paucispinis, M. liberiensis, M. goro (Fig. 50c), M. niger, and M. ubangensis it is shorter, but only slightly so extending to the posterolateral edge of the ectopterygoid at its border with the quadrate and endopterygoid. The corono- meckelian in M. moorii (Fig. 43a) has about the same extent as it does in M. cunningtoni, but is distinguished by its prominently forked posterior end. MASTACEMBELOIDEI I: ANATOMICAL 81 A feature common to all African species with a long coronomeckelian is the low, broad coronoid dentary process (p. 80). In African species coronomeckelian length is apparently correlated with the type of coronoid process present. Species with a relatively short corono- meckelian (e.g. M. brichardi and M. brachyrhinus) have, without exception, a tall, narrow coronoid process, whilst those with a relatively long coronomeckelian (e.g. M. cunningtoni and M. liberiensis) have, again without exception, a low, broad coronoid process. Thus, there is an inverse relationship between coronomeckelian length and coronoid process height. A low, broad coronoid process occurs (as described above) in M. zebrinus, M. pancalus and the Macrognathus species. The Macrognathus coronomeckelian is a larger bone than that found in M. mastacembelus; in Macrognathus aculeatus (Fig. 46c) it extends from the dorsomedial margin of the anguloarticular, across the lateral face of the ectopterygoid and quadrate to the latter's border with the metapterygoid. Com Aa Fig. 47 Mastacembelus sinensis, left hyo-pterygoid arch, preoperculum and jaw bones in lateral view. The length of the coronomeckelian in M. zebrinus and M. pancalus (which both have a particularly low, broad coronoid process, Fig. 46a & b) also exceeds that in M. mastacembe- lus and even that in Macrognathus since it extends posteriorly across the dorsal margin of the anguloarticular to the posterolateral face of the endopterygoid. A relatively short coronomeckelian occurs in Mastacembelus sinensis (Fig. 47) and extends posteriorly from the dorsomedial margin of the anguloarticular but does not reach the anteroventral edge of the ectopterygoid. A relatively tall, narrow coronoid process, described earlier (p. 80) occurs in this species. The type of coronoid process and the condition of the coronomeckelian in Asian mastacembeloids thus appear to have the same relationship as in the African species. The relationship between these bones may be associated with several features of the adductor musculature inserting on them (A2 & A3 division); this will be discussed elsewhere (Travers, 1984). There is little interspecific variation in the morphology of the anguloarticular. The lack of an ascending process (coronoid expansion) on the bone in M. mastacembelus (Fig. 4) is characteristic of most taxa, but the upper edge of the anguloarticular has a moderately high, broad-based coronoid expansion in Mastacembelus zebrinus, M. pancalus and Macro- gnathus species. In these (e.g. see Macrognathus aculeatus; Fig. 46c) the dorsal expansion tapers to a low peak which lies just below the anterior end of the coronomeckelian. An 82 R. A. TRAVERS expanded dorsal edge of the anguloarticular is not found in any other Asian or African species. The dorsal edge of the anguloarticular is notched in Mastacembelus micropectus (Fig. 43c), the anterior end of the coronomeckelian lying within the notch. The position of the facet on the anguloarticular (posterodorsal angle) described in M. mastacembelus (p. 20) is typical of all taxa apart from the Macrognathus species (Fig. 46c) where it notches the dorsal edge anterior to the posterodorsal angle of the bone. Thus, the mandibular joint lies anterior to the posterior end of the anguloarticular. Hyopalatine arch The bones of the hyopalatine arch exhibit a number of interspecific differences, but apart from these there are only slight proportional changes in the overall arrangement of the arch. The anterior edge of the hyomandibula shaft in M. mastacembelus (Fig. 5) bears a small descending spur. This is an invariable feature of all Asian mastacembeloids with the excep- tion of Chaudhuria (Fig. 1 7a) and Pillaia (Fig. 1 7b), but is not found universally among the African species. For example, among the Tanganyikan species a prominent spur occurs only in Mastacembelus cunningtoni and to a lesser extent in M. micropectus, M. moorii and M. ophidium (Fig. 43 a-c). Other African species with a hyomandibular spur include, Mastacembelus brachyrhinus, M. marmoratus, M. paucispinis, M. vanderwaali and the undescribed species. The hyomandibula and metapterygoid bones are unconnected in the majority of masta- cembeloids, a condition typical of almost all species except Mastacembelus sinensis (Fig. 47), Chaudhuria (Fig. 17a) and Pillaia (Fig. 17b). In these taxa the posterolateral edge of the metapterygoid lies in close proximity, attached by connective tissue, to the anteroventral edge of the hyomandibula. The wide gap between these bones in all other mastacembeloids may be related to the particularly large symplectic. Disproportionate growth of this bone, compared to other suspensorial elements, may have resulted in it displacing the metaptery- goid and other suspensorial bones away from the hyomandibula (see Figs 43, 44 and 50). The anterior edge of the metapterygoid is connected by a narrow cartilaginous interface to the posterolateral edge of the quadrate in all species examined. The ventral dentate suture, below the cartilage interface, which also connects these elements in M. mastacembelus (Fig. 5), is absent in other Asian species and is present in only 4 African species, all from Lake Tanganyika viz., M. cunningtoni, M. moorii, M. ophidium and M. zebratus. A small bony spur rises dorsolaterally from the ventral edge of the metapterygoid in Mastacembelus ubangensis (Fig. 48). The upper edge of the dorsal lamina on the symplectic in this species is also produced into a short descending process. Pal Fig. 48 Mastacembelus ubangensis, left hyopalatine arch and preoperculum; lateral aspect. MASTACEMBELOIDEI I: ANATOMICAL 83 The symplectic (as noted above) is a large element in the hyopalatine arch. Its upper sur- face, in the majority of species, is produced into a thin lamina with an irregular dorsal edge. Compared with its size in M. mastacembelus (Fig. 5), the symplectic is relatively small in Mastacembelus sinensis (Fig. 47), Chaudhuria (Fig. 17a) and Pillaia (Fig. 17b). Associated with its small size in these species is the close contact between the hyomandibula and metapterygoid (discussed above). The anterior edge of the quadrate is indented in Mastacembelus zebrinus, M. pancalus and in all Macrognathus species (Fig. 46a-c). This curved edge corresponds with the anterior edge of a recess in its anteromedial face, in which lies the large, horn-like ectopterygoid process. A circular facet on the margin of the quadrate is unique to Mastacembelus pancalus (Fig. 46b); the facet articulates with a similar facet on the posterolateral face of the ectopterygoid, dorsal to its horn-like process. Apart from this variation, the form of the quadrate is remarkably constant throughout the group. Considerable variation occurs in the morphology of the endopterygoid. The boomerang- shaped bone in Mastacembelus mastacembelus (Fig. 5) also occurs in M. armatus, M. erythrotaenia, M. oatesii and M. unicolor (see Fig. 49). The anterior process of the endopterygoid in these species extends below and beyond the anterodorsal connection between the ectopterygoid and lateral ethmoid. In no other Asian or African species examined does the endopterygoid contribute to the anterior articulation between the suspen- sorium (ectopterygoid) and neurocranium (lateral ethmoid). However, in Mastacembelus maculatus (Fig. 49c) the anterior tip of the endopterygoid does not lie far from the lateral ethmoid and appears to represent an intermediate condition. The posterior end of the endopterygoid is distinctly modified in Macrognathus (Fig. 46c), Mastacembelus frenatus (Fig. 50a), M. marmoratus, M. niger, M. sclateri and M. ubangensis (Fig. 48). In these taxa the posterior end of the bone is subdivided into 3 prong-like processes whose tips are connected to short tendons running from the adductor arcus palatini muscle. The endopterygoid is less modified in the remaining mastacembeloids examined (e.g. M. congicus (Fig. 50b). However, there is a marked tendency for the bone to be reduced in size in three species from the lower Zairean rapids (Mastacembelus brichardi, M. crassus and M. aviceps Fig. 44a-c: possibly M. latens as well). Here the endopterygoid is little more than a small splinter of bone connected to the dorsal end of the quadrate. In Mastacembelus sinensis, Chaudhuria and Pillaia, however, the bone is entirely absent (see Figs 47 and 1 7a &b). The deep anterolateral face of the ectopterygoid and its direct articulation with the lateral ethmoid (as described in M. mastacembelus, p. 21), are features common to almost all mastacembeloids. The disproportionate anterolateral depth of the ectoptergygoid gives it a sinusoidal shape in most Asian and African taxa. Variation occurs both in the relative depth of the bone in some species, and in the length of its anterodorsal process articulating with the lateral ethmoid. When compared with other Tanganyikan species, Mastacembelus moorii and M. ophidium (Fig. 43a & b) have an ectopterygoid with a relatively shallow anterolateral face and a long dorsal process. The bone in Zairean rapids species M. aviceps and M. crassus (Fig. 44 a & b) is similar to that in M. moorii and M. ophidium. The most extreme ectopterygoid variation occurs, however, in Chaudhuria (Fig. 1 7a) and Pillaia (Fig. 1 7b), and to a lesser extent in Mastacembelus sinensis (Fig. 47). The bone in M. sinensis extends anterodorsally as a long, narrow process, its tip articulating with the lateral ethmoid. This process is particularly long and anteromedially curved in Chaudhuria and Pillaia; it does not contact the lateral ethmoid, but extends below it along the lateral face of the vomer. The depth of the anterolateral face of the ectopterygoid decreases sequentially in M. sinensis, Chaudhuria and Pillaia (compared Figs 47 and 17a & b), and a progressively smaller region of the bone in these species lies below the quadrate. 84 R. A. TRAVERS CMen Met EndAP Ect Com Fig. 49 Endo-ectopterygoid connection, left side, in (a) Mastacembelus erythrotaenia, (b) Mastacembelus armatus and (c) Mastacembelus maculatus', viewed obliquely from a dorso- lateral position. Modification of the ectopterygoid is associated with the weak, flake-like palatine (auto- palatine) in mastacembeloids. The ectopterygoid appears to have replaced the palatine func- tionally, both with respect to its role as the anterior articulation point of the suspensorium with the neurocranium (discussed in Part II), and with respect to the palatine's contribution to the bony roof of the mouth. The form of the palatine (other than interspecific variation in its dentition and connection to the lateral ethmoid) in M. mastacembelus (p. 2 1 & Fig. 5) is seen in all taxa except Chaudhuria and Pillaia in which the bone is absent. All Asian, and the majority of African species lack a palatine, tooth bearing, alveolar sur- face (dermopalatine). When present, palatine teeth are caniniform with posteriorly directed MASTACEMBELOIDEI I: ANATOMICAL 85 tips, arranged in rows, the number of which are interspecifically variable. A single row of teeth occurs in the specimens of Mastacembelus ophidium (Fig. 43b) examined, two rows occur in M. congicus (Fig. 50b), M. sclateri, M. loennbergii and M. nigromarginatus, and three rows in M. longicauda (Fig. 33a), M. moorii (Fig. 43a) and M. paucispinis (Fig. 35a Pop Com Aa Ra Fig. 50 Left hyopalatine arch, preoperculum and jaw bones in (a) Mastacembelus frenatus, (b) Mastacembelus congicus (jaw bones not shown) and (c) Mastacembelus goro; lateral aspect. 86 R. A. TRAVERS & b). Intraspecific variation in tooth row number is also common; for example a single specimen of Mastacembelus ellipsifer has a short toothplate with one row of small canini- form teeth on the left palatine and only a single tooth carried on a very small toothplate, on the right palatine. A specimen of Mastacembelus vanderwaali and one of M. brachyrhinus have, respectively a single tooth on the left and on the right palatine. Similarly, two teeth are present on the left palatine only of the single specimen of the new Mastacembelus species (Fig. 36a & b) from the Cameroonean rapids. The palatine is connected to the ventrolateral face of the lateral ethmoid in the majority of Asian and in many African species, by a weak, posterodorsally directed spur which ascends from its dorsal edge (see description for M. mastacembelus, p. 2 1 ). A palatine spur is absent in Mastacembelus maculatus (Fig. 26 a & b), M. pancalus (Fig. 28 a & b) and the Macrognathus species (Figs 29 a & b and 30 a & b) among the Asian mastacembeloids. Among the African species, Mastacembelus ophidium (Fig. 43b) is the only East African species lacking a palatine spur, but it is also absent in Mastacembelus vanderwaali, M. stappersii and 3 species from the lower Zairean rapids (M. brichardi, M. aviceps and M. crassus; Fig. 44a-c). Among the West African species a relatively large number, including Mastacembelus liberiensis, M. goro (Fig. 50c), M. longicauda (Fig. 33a), M. loennbergii, M. batesii and M. brevicauda, lack the spur. The palatine spur is thus a relatively constant feature amongst Asian mastacembeloids but has a somewhat mosaic distribution among the African species. Opercular series The thinness of the operculum (posterior flap), and of the sub- and inter op ercular bones are characteristic features of mastacembeloids. Interspecific variation occurs predominantly in the morphology of the preoperculum, which shows some intraspecific variability as well. Preopercular features that vary markedly are (1) the number of sensory canal pores, (2) the number of preopercular spines and (3) the relative length of the horizontal limb. In the Asian and African mastacembeloids the preopercular sensory canal lies within the lateral face of the bone, and opens to the surface via a number of circular pores along both the horizontal and vertical limbs. In most of the Asian species examined there are five sensory canal pores along the ventro- lateral face of the bone-enclosed preopercular sensory canal; three on the horizontal limb and two on the vertical limb. A branched preopercular sensory canal occurs in a number of Asian species. The two pos- terior pores in the horizontal limb and the ventral pore in the vertical limb of the preopercu- lum in Mastacembelus pancalus and Macrognathus species (Fig. 46b & c) lie at the tip of a short descending branch from the main canal. Branched canals are characteristic features of these fishes, associated with the broad, lateral face and relatively short length of the preoperculum. Only two short branches descend from the main canal in Macrognathus aculeatus (Fig. 46c) which has a particularly short preoperculum. The preopercular bones in Chaudhuria and Pillaia are exceptional amongst mastacem- beloids. In Pillaia (Fig. 1 8b) the canal is indistinct and is restricted to the central region of the lateral face of the bone, whereas in Chaudhuria (Fig. 18a) there is no canal in the preoperculum. Based on the number of preopercular canal pores, the African taxa can be divided into two groups viz., those with 5 and those with 4 pores; all the Asian taxa have 5 pores. The African species with 5 pores include half the species found in Lake Tanganyika (Mastacem- belus albomaculatus, M. ellipsifer, M. frenatus, M. moorii, M. ophidium and M. platysomd), as well as Mastacembelus shiranus, M. stappersii, M. paucispinis, M. reticulatus and the undescribed species. Almost all the remaining African species have 4 pores, the only excep- tion being 3 species from the lower Zairean rapids, of which Mastacembelus brachyrhinus, has 3 and M. crassus and M. aviceps have 2 pores. MASTACEMBELOIDEI I: ANATOMICAL 87 A clearly reductional sequence is manifest in the endemic Zairean rapids species, running from 5 pores in M. paucispinis, through 4 in M. brichardi, 3 in M. brachyrhinus, to 2 pores in the highly derived M. crassus and M. aviceps. Furthermore, in M. crassus and M. aviceps the dorsal opening of the preopercular sensory canal does not lie at the tip of the bone but along its posterolateral edge (Fig. 44a & b). The lack of spines on the preoperculum in M. mastacembelus (p. 23) is a feature common to a number of Asian species including Mastacembelus maculatus, all Macrognathus species, Mastacembelus sinensis, Chaudhuria and Pillaia. Preopercular spines occur in the other Asian species examined namely Mastacembelus armatus, M. erythrotaenia, M. oatesii, M. unicolor, M. zebrinus and M. pancalus. Although intraspecific variability in the number of spines is common, generally three or four occur in each of these species. This variability may even occur between the number of spines on the left and right preoperculum in the same individual. For example, in a specimen of M. zebrinus (Fig. 46a) three spines are present on the left and four on the right side. Considerable variation in preopercular spines also occurs amongst the African mastacembeloids. Many species from east and southern Africa have a single spine, e.g. Mastacembelus albomacula- tus, M. moorii, M. plagiostomus, M. platysoma, M. tanganicae and M. zebratus. However, Mastacembelus cunningtoni and M. ellipsifer are characterised by two spines, while M. frenatus, M. ophidium, M. micropectus, M. shiranus, M. stappersii and M. vanderwaali lack preopercular spines. Spines are absent in the west African Mastacembelus niger\ a single spine occurs on the left side in one specimen of M. batesii and M. nigromarginatus. The remaining west African species have two or three spines, as do Mastacembelus ubangensis and the undescribed species. Among the mastacembeloids endemic to the Zairean rapids (Roberts & Stewart, 1976) there appears to be a sequential loss of spines from two in Mastacembelus paucispinis, one in M. brichardi and M. brachyrhinus, to none in the highly derived Mastacembelus crassus and M. aviceps. Apart from these rapid-dwelling species the number of preopercular spines varying from none to four, appears to have a mosaic distribution among both the Asian and the African mastacembeloid taxa. The dimensions of the horizontal preopercular limb vary from relatively short and wide (e.g. Mastacembelus ophidium and M. micropectus, Fig. 43b & c) to long and narrow (e.g. Mastacembelus vanderwaali and M. cunningtoni) among members of both the Asian and the African mastacembeloids. This variation may be associated with the neurocranial and jaw length. The vertical limb is generally shorter than the horizontal limb in the majority of masta- cembeloids. However, the vertical limb is particularly long in four species from west Africa; Mastacembelus longicauda, M. brevicauda, M. nigromarginatus and M. reticulatus. Hyoid arch There is remarkably little interspecific variability in the morphology of the hyoid arch. The condition of the arch in Mastacembelus mastacembelus (p. 23) is typical of that found generally among both Asian and African members of the suborder. Variation in the relative length of the basihyal, as compared with its condition in M. mastacembelus (Fig. 8), occurs in some species. It is relatively short in Mastacembelus moorii and Mastacembelus ophidium from Lake Tanganyika, having a wide dorsal surface and deep ventral ridge, the former feature giving the bone in M. moorii a particularly wide, spatulate surface. The long basihyal in Mastacembelus erythrotaenia is distinguished by its relatively narrow dorsal surface and low ventral ridge. The anterior and posterior ceratohyal are joined by a series of dentate sutures in all masta- cembeloids except Chaudhuria (Fig. 20ai) and Pillaia (Fig. 20bi). In these taxa a distal flange on the anterior ceratohyal lies in a recess on the posterior face of the posterior ceratohyal; the two elements are connected by a straight suture and a cartilaginous interface. A variable number of irregular short spikes extend into the cartilaginous interface between DHh HAF R. A. TRAVERS ACh PCh VHh Fig. 51 Mastacembelus sinensis, left hyoid arch, in lateral view. the bones in Mastacembelus sinensis (Fig. 5 1 ) seemingly a variant of the condition shown by the majority of species. The urohyal shows considerable variation (compared to its condition described in M mastacembelus p. 24), particularly with respect to its length and the arrangement of its pos- terior, prong-like processes. However, it is in its connection with basibranchial 1 that the most prominent interspecific variation occurs. A direct connection between the urohyal and basibranchial 1, either by way of an ascending process (or processes) or a synchondral joint (discussed below) occurs in all Asian mastacembeloids except Mastacembelus sinensis, Chaudhuria and Pillaia. In M. sinensis (Fig. 52a) and Pillaia the tip of an ascending process on the dorsal surface of the urohyal is connected to the underside of basibranchial 2. In Chaudhuria there is neither an ascending urohyal process nor a direct articulation with basibranchial 1 . Since none of the African species has a direct connection between the anterodorsal surface of the urohyal and the ventral edge of basibranchial 1 , the process on the urohyal and its connection to basibranchial 1 in the Asian mastacembeloids appears to have resulted in a variety of specific characters. The urohyal in Mastacembelus zebrinus (Fig. 52b) is connected more closely to basibran- chial 1 and may represent an intermediate condition between the type of urohyal develop- ment seen in M. mastacembelus and the direct urohyal-basibranchial 1 articulation in the Macrognathus species. The anterodorsal surface of the urohyal in M. zebrinus lies directly below the ventral edge of the keel on basibranchial 1 (p. 90). A long, narrow process ascends anterodorsally from the urohyal along the posterior edge of the keel on basibranchial 1. The anterior edge of this process is connected to the posterior edge of the keel, and its tip contacts the ventral surface of basibranchial 2. Although the urohyal lacks an ascending process in a number of Asian mastacembeloids, these taxa are distinguished by a direct articulation between the anterodorsal surface of the urohyal and the keel on basibranchial 1 . In place of an ascending process in Mastacembelus pancalus (Fig. 53a) there is a depression with wide lateral and posterior rims. The ventral edge of basibranchial 1 is cartilaginous and articulates synchondrally with the dorsal surface of this depression in the urohyal. In Macrognathus siamensis (Fig. 53b) the dorsal surface of the urohyal is level but has MASTACEMBELOIDEI I: ANATOMICAL 89 Bh Bb1 Bb2 Bb3 Hb3Tp Bb1K UhAP Bb2VP Hb3 Bb1K UhAP Uh Fig. 52 Basibranchial/urohyal arrangement in (a) Mastacembelus sinensis and (b) Mastacem- belus zebrinus; lateral aspect, left side. a shallow groove in which the cartilaginous ventral edge of basibranchial 1 articulates. The bifurcated anterior end of the urohyal in Macrognathus ami and Macrognathus aculeatus (Fig. 53c) forms a shallow longitudinal groove along its dorsal surface in which lies the cartilaginous ventral edge of basibranchial 1. The posterior region of the urohyal in Mastacembelus pancalus and the Macrognathus species (Fig. 53a-c), generally lacks the prong-like processes that occur in other mastacembeloid taxa. The urohyal in Mastacem- belus oatesii (Fig. 54) also lacks an ascending process. The anterior tips of the urohyal in this species are particularly deep and form a groove between their medial edges. The ventral edge of basibranchial 1 lies along this groove but it is not cartilaginous, and the elements do not articulate in the manner described for M. pancalus and Macrognathus. An ascending process (or processes) on the dorsal surface of the urohyal in Mastacembelus armatus, M. erythrotaenia and M. maculatus is connected to the ventral edge of basibranchial I in an arrangement similar to that in M. mastacembelus (p. 24, Fig. 9). 90 a R. A. TRAVERS Bb1 Bb2VP Bb3 Hb3AP BblKC UhF Uh Fig. 53 Basibranchial/urohyal arrangement in (a) Mastacembelus pancalus, (b) Macrognathus siamensis and (c) Macrognathus aculeatus; lateral aspect, left side. Branchial arches The basibranchial elements described in M. mastacembelus (Fig. 8) are typical of those found throughout the group. The deep ventral 'keel' on basibranchial 7 is a constant feature of almost all mastacembeloid taxa, but is absent in Mastacembelus sinensis, Chaudhuria and MASTACEMBELOIDEI I: ANATOMICAL Bb1 Bb2VP DUO 91 Hb3Tp Bb1K Fig. 54 Mastacembelus oatesii, basibranchial/urohyal arrangement; lateral aspect, left side. Bh + Bb1 Bb2 Bb3 Hb3 Uh Bh Bb1K Bb2VP Bb3 Hb3 Fig. 55 Basibranchial/urohyal arrangement in (a) Mastacembelus aviceps and (b) Mastacembelus crassus\ lateral aspect, left side. 92 a R. A. TRAVERS Bb1 Bb2VP Bb3 Hb3Tp Fig. 56 Basibranchial/urohyal arrangement in (a) Mastacembelus nigromarginatus and (b) Mastacembelus ubangensis; lateral aspect, left side. Pillaia (see p. 46). The keel is particularly well-developed in Mastacembelus pancalus and Macrognathus species (Fig. 53a-c) where the ventral knife-edge is cartilaginous. The only variation in the 'keel' on basibranchial 1 among the African species is seen in the relatively low 'keel' of Mastacembelus aviceps and M. crassus (Fig. 55a & b). A pair of processes, each descending from the posterolateral corner of basibranchial 2 (as described in M. mastacembelus p. 25, Fig. 9), occur in most mastacembeloids. Mastacem- belus sinensis, Chaudhuria and Pillaia among the Asian, and M. aviceps among the African species are again exceptional in that they lack these processes. The tips of the descending processes on basibranchial 2 are connected ligamentously to the posteroventral edge of the keel on basibranchial 1. Part ossification of the ligaments occurs in two African species, Mastacembelus nigromarginatus and Mastacembelus ubangensis (Fig. 56a & b). Among the west African species each ligament is almost comple- tely replaced by the descending processes arching longitudinally across the ventral surface of basibranchial 2. The anterior tips of the processes in these species contact the keel on basibranchial 1 , and a pair of ventral arches of this type are a characteristic feature of Masta- cembelus goro, M. flavomarginatus, M. greshoffi, M. longicauda, M. loennbergii, M. batesii and M. brevicauda (e.g. Fig. 57a-c). The ventral aorta passes longitudinally along the surface of the basibranchial elements and lies between the descending arches on basibranchial 2. MASTACEMBELOIDEI I: ANATOMICAL 93 Bb1K HbSTp Bb2VPA Bb2VPA Fig. 57 Basibranchial/urohyal arrangement in (a) Mastacembelus longicauda, (b) Mastacembelus loennbergii and (c) Mastacembelus batesii; lateral aspect, left side. 94 R. A. TRAVERS Cb5 Cb1 Hb3Tp Bb4 Bh Fig. 58 Mastacembelus maculatus, hyoid and lower gill arches in dorsal view. The first afferent arteries pass between each arch and the ventral surface of basibranchial 2. There is only slight interspecific variation in the hypobranchial bones, apart from two features of hypobranchial 3; the presence of a small toothplate joined to the dorsal surface, and the lack of an anteroventral process extending below hypobranchial 2. A round toothplate fused to the dorsal surface of hypobranchial 3 (Fig. 58) occurs in the Asian mastacembeloids except M. mastacembelus (Fig. 8) and Pillaia (Fig. 20bi). A fused toothplate on hypobranchial 3 is also of frequent occurrence among the African taxa (e.g. Figs 60-63). It is, however, absent in the endemic species from the lower Zairean rapids (i.e. Mastacembelus paucispinis, M. brachyrhinus, M. brichardi, M. crassus, M. aviceps), and Mastacembelus marmoratus, M. niger, M. sclateri, M. ubangensis and the undescribed species. The second important feature of hypobranchial 3 is its long anteroventral process. In M. mastacembelus this process extends anteriorly below hypobranchial 2 (Fig. 8), with its tip connected ligamentously to basibranchial 2. This process occurs universally among the Asian taxa (e.g. Figs 58 & 59) and in the majority of African species (e.g. Figs 60 & 61). It is absent in a number of species from western Africa, including Mastacembelus batesii, M. brevicauda, M. flavomarginatus, M. goro, M. greshoffi, M. liberiensis, M. loennbergii, M. longicauda, M. niger, M. nigromarginatus, M. reticulatus and M. sclateri (see Figs 56, 57 & 62). In these species if the anterior edge of hypobranchial 3 is produced at all it is MASTACEMBELOIDEI I: ANATOMICAL 95 Cb5 Cb1 PCh ACh DHh VHh Fig. 59 Mastacembelus zebrinus, hyoid and lower gill arches in dorsal view. in the form of a short stump, (e.g. M. liberiensis, Fig. 63); but there is no ligamentous attachment to basibranchial 2. Ceratobranchial 5 is the only other ventral gill arch element to which a toothplate is fused. Interspecific variation in the dorsal surface area of the toothplate is related to its degree of medial expansion. Compared with M. mastacembelus (Fig. 8), it is particularly narrow in M. maculatus (Fig. 58), whereas, the Tanganyikan species Mastacembelus cunningtoni and M. tanganicae (Figs 60 & 61) are distinguished by their wide medial expansion of the tooth- plate. The toothplate does not contact its partner in the midline in any species. The dentition of the toothplates fused to the ventral gill arch elements consist of canini- form teeth, tips directed posteriorly, varying interspecifically in size. The small, unfused toothplates irregularly positioned along the length of ceratobranchials 1-4 and hypobran- chials 1-3, show considerable inter and intra-specific variation in size and number. When present, the dentition is of small conical teeth (see Figs 59-61). The dorsal gill arch elements in all taxa lie posterior to the neurocranium, and show a remarkable lack of interspecific variability. The arrangement of the epibranchial (1-4) and pharyngobranchial (2-3) bones in M. mastacembelus (Fig. lOa & b, p. 26) is typical for most mastacembeloids. Pharyngobranchial 1 is lacking in all mastacembeloids. This may be associated with the posterior position of the dorsal gill arch elements since its absence is a feature common to most eel-shaped fishes (Nelson, 1970). In one specimen of Pillaia, pharyngobranchial 2 is 96 R. A. TRAVERS CbSTp Bb4 Hb1 PCh ACh Bb1 DHh Bh Fig. 60 Mastacembelus cunningtoni, hyoid and lower gill arches in dorsal view. present as a small cartilaginous element within a collagenous strand linking the tips of epibranchials 1 and 2, (a condition generally found only at an early embryonic stage), but in a second specimen a well-developed pharyngobranchial 2 is present (Fig. 20bii). The anteromedial extension of pharyngobranchial 3, (beyond its point of contact to epibranchial 2) and its connection to the tip of both pharyngobranchial 2 and epibranchial 1 , is a feature common to most taxa (as seen in M. mastacembelus, Fig. 1 Oa & b). However, pharyngobranchial 3 lacks an anterior extension in Chaudhuria (Fig. 20aii) and Pillaia (Fig. 20bii); the arrangement of this bone in M. sinensis (Fig. 66) appears to be somewhat inter- mediate between that found in Chaudhuria and Pillaia and the modal condition. The fourth pharyngobranchial element is invariably cartilaginous in mastacembeloids. MASTACEMBELOIDEI I: ANATOMICAL 97 Cb5 PCh ACh Bb1 DHh VHh Bh Fig. 61 Mastacembelus tanganicae, hyoid and lower gill arches in dorsal view. The most variable feature of the dorsal gill arch elements is the unfused toothplates. Except in Chaudhuria and Pillaia, small irregularly positioned toothplates lie along the antero- ventral face of epibranchials 1 and 2 in all Asian mastacembeloids (Fig. lOa). Amongst the African representatives, Lake Tanganyikan species have similar epibranchial toothplates, (discussed below), but apart from these groups plus Mastacembelus stappersii and Mastacembelus congicus, plates are absent in African mastacembeloids. The best developed epibranchial dentition occurs in the large, lacustrine, predatory species from Lake Tanganyika (e.g. M. cunningtoni and M. moorii). In these species the anteroventral edge of epibranchials 1 and 2 is expanded to form a wide bony lip, whose ventral surface supports a series of relatively large toothplates. In a large stained specimen of M. cunningtoni (Fig. 64) held at the BM(NH) the toothplate was considered by Nelson (1969: 497) to be fused to epibranchial 1 . Close examination of this specimen showed that although the toothplate is indeed tightly connected to epibranchial 1, it can be stripped intact from the overlying bone. In another Tanganyikan species (Mastacembelus micropectus Fig. 65) the toothplates are inseparably fused to epibranchial 1 . The pharyngobranchial elements generally support \hzfused toothplates of the dorsal gill arches, and are arranged in a way similar to that described for M. mastacembelus (p. 26). A toothplate is generally fused to the ventral surface of pharyngobranchial 2 (as described 98 R. A. TRAVERS Cb5 HbSTp Bb4 PCh Fig. 62 Mastacembelus flavo marginal us, hyoid and lower gill arches in dorsal view. in M. mastacembelus p. 27). Notable exceptions, which lack this toothplate, are the endemic lower Zairean rapids species (M. paucispinis, M. brachyrhinus, M. brichardi, M. crassus and M. aviceps), M. marmoratus and most west African taxa (M. batesii, M. brevicauda, M. goro, M. greshqffi, M. liberiensis, M. loennbergii, M. longicauda, M. marchiiandM. niger). Promi- nent pharyngobranchial 3 and pharyngobranchial 4 toothplates are features of all mastacem- beloids. The dentition on these toothplates, like that on the ventral plates, consists of relatively large caniniform teeth. On the unfused toothplates, the teeth are very much smaller and are usually conical, but are small and caniniform on the large toothplates occurring in the lacustrine species. Pectoral girdle The pectoral girdle shows remarkably few interspecific differences, either in overall propor- tions or in the shape of its constituent bones. The postcranial position of the girdle (adjacent to 3rd and 4th abdominal vertebrae) and the lack of a posttemporal bone connecting it to the neurocranium (as described in M. mastacembelus p. 27) are features common to all taxa. Variation in the ventral limb of the cleithrum occurs among the Asian species. The cleithrum has a particularly deep ventrolateral face in Mastacembelus zebrinus (Fig. 67). Its ventromedial margin contacts its partner in a median symphysis and gives the pectoral girdle a 'keeled' ventral region. The depth of this keel increases both the surface area MASTACEMBELOIDEI I: ANATOMICAL 99 Cb5 HbSTp Hb1 Bb4 PCh Bb1 Bh Fig. 63 Mastacembelus liberiensis, hyoid and lower gill arches in dorsal view. available for muscle attachment, laterally, and that of the symphysis between the two halves. The ventral limb of the cleithrum in Mastacembelus pancalus (Fig. 68a) and in the Macrognathus species (Fig. 68b) is also deep but proportionally less so than in M. zebrinus. The strengthening effect derived from expansion in this region of the girdle may be related to burrowing habits, and in particular the type of burrowing mechanism employed by these taxa (see Part II; Travers, 1984). A cleithrum with a short, indistinct ventral limb occurs in a number of African taxa including Mastacembelus brichardi, M. crassus, M. aviceps (Fig. 69a) from the lower Zairean rapids; M. micropectus and M. plagiostomus (Fig. 69b) from Lake Tanganyika. In these species the ventral limb of the cleithrum is shallow and this, together with its slight anteroventral curvature, gives the bone a relatively straight overall shape. An accompanying tendency towards reduction of pectoral fin size occurs in these taxa. The dorsal edge of the cleithrum is serrated in the undescribed Mastacembelus species (Fig. 70), M. nigromarginatus (Fig. 72) and M. stappersii; this contrasts with the smooth edge found in the majority of species. A postcleithrum is absent in all mastacembeloids. The scapula is pierced by a large foramen which is completely bone enclosed in all Asian taxa as shown for example in Mastacembelus mastacembelus (Fig. 1 1 ) and the Macro- 100 R. A. TRAVERS Eb4 UTp Fig. 64 Mastacembelus cunningtonl, upper gill arches; ventral aspect, right side. gnathus species (Fig. 68b). The anterior edge of the foramen in the majority of African species, however, lies across the anterolateral margin of the bone and is enclosed by cartilage (see Figs 69, 70, 72 & 73). Four, spool-shaped radials occur in all species. The two upper radials articulate with the posterior edge of the scapula, the third with the cartilage interface between it and the coracoid, and the fourth with the posterior edge of the coracoid (as described in M. masta- cembelus p. 28). Radials with bifurcated (or even trifurcated) distal ends occur mosaically. The distal tips of all four radials are bifurcated in Mastacembelus maculatus and M. greshoffi; the 1st, 2nd and 3rd are bifurcated in Macrognathus aculeatus (Fig. 68b); the 2nd and 3rd in Mastacembelus ophidium; the 2nd in M. loennbergii, while the 2nd and 4th are trifurcated in M. sinensis and the 2nd is trifurcated in M. liberiensis. The radials in a juvenile, 4 cm long, specimen of M. maculatus (Fig. 71) are cartilaginous and divided along most of their length (apart from the anterior ends), thus giving the appear- ance of 8 radials (i.e. the primitive teleostean complement: Jarvik, 1980). This suggests that the adult condition of 4 radials results from the fusion of neighbouring pairs of elements during ontogeny. In some cases each pair remains incompletely fused in the adult. There are interdigiting processes between the radials in Mastacembelus nigromarginatus (Fig. 72), whilst in M. zebrinus, M. brachyrhinus and the undescribed species the 1st and 2nd radials are coalesced. Such radial fusion also occurs in some M. tanganicae, but in other specimens the 1st and 2nd radials are separate, indicating that this feature may be intra- specifically variable. The fusion between radials, the presence of interdigitating processes and, in some specimens, the coalescence of certain radials are all possibly associated with strengthening the pectoral fin base. The 22 pectoral fin rays in Mastacembelus mastacembelus (p. 28) are intermediate in number between the highest (26 in Mastacembelus oatesii) and lowest (6 in the very small pectoral fin of Mastacembelus micropectus; in one individual they are completely lacking). MASTACEMBELOIDEI I: ANATOMICAL 101 Pb3. Pb2 Eb4 FTp Eb4 FTp Pb3 Pb2 Fig. 65 Mastacembelus micropectus, upper gill arches (a) ventral aspect, (b) dorsal aspect; right side. The pelvic girdle is absent in all mastacembeloids, and apart from Mastacembelus longi- cauda (Fig. 73), no pelvic elements remain. In a specimen of this species a pair of splinter-like bones lie longitudinally between the cleithra and are thought to represent basipterygia. Vertebral column There is only slight interspecific variation in the morphology of the abdominal and caudal vertebrae. The vertebral elements described in M. mastacembelus (p. 29) are, in general, typical for most taxa. A hemispherical condyle on the first abdominal centrum (Fig. 12) is present in all mastacembeloids. Wide, laterally compressed neural spines occur on the anter- ior abdominal vertebrae. These are confined to the first four vertebrae in M. mastacembelus (Fig. 12), and in most Asian forms, although the first 6 vertebrae have wide spines in all Macrognathus species, and only the first 2 in Pillaia (Fig. 21bii). 102 R. A. TRAVERS Pb3 Pb2 Fig. 66 Mastacembelus sinensis, upper gill arches; dorsal aspect, right side. PFR Cor Fig. 67 Mastacembelus zebrinus, pectoral girdle; lateral aspect, left side. MASTACEMBELOIDEI I: ANATOMICAL 103 Sc PFR Cor Fig. 68 Pectoral girdle in (a) Mastacembelus pancalm, and (b) Macrognathus aculeatus; lateral aspect, left side. 104 R. A. TRAVERS PFR R4 Cor R4 Cor PFR Fig. 69 Pectoral girdle in (a) Mastacembelus aviceps, and (b) Mastacembelus crassus\ lateral view, left side. MASTACEMBELOIDEI I: ANATOMICAL Sc ScaF 105 PFR Cor Fig. 70 Pectoral girdle in the undescribed Mastacembelus species; lateral aspect, left side. PFR Fig. 71 Juvenile Mastacembelus maculatus (S.L.4 cm.) pectoral girdle; lateral aspect, left side. In the African species wide neural spines are typically developed on the first 5 or 6 abdominal vertebrae. The first 8 vertebrae have wide neural spines in the west African Mastacembelus loennbergii and M. reticulatus and there are 9 such spines in M. marmoratus from Congo. Anteroposteriorly expanded neural and haemal spines may also occur and are particularly prominent on all posterior caudal vertebrae in the 4 lacustrine species, Mastacembelus ellipsifer, M. frenatus, M. moorii and M. ophidium (discussed below). Elongated, narrow 106 R. A. TRAVERS R4 PFR Cor Fig. 72 Mastacembelus nigromarginatus, pectoral girdle; lateral view, left side. R1-4 Fig. 73 Mastacembelus longicauda, pectoral girdle; lateral aspect, left side. MASTACEMBELOIDEI I: ANATOMICAL 107 neural and haemal spines are found in some Asian taxa, including Mastacembelus pancalus, M. zebrinus, M. keithi, M. caudiocellatus and Macrognathus species (see Part II). The length of their spines gives these taxa a characteristic deep-bodied appearance. The asymmetry of the centra as described in M. mastacembelus (p. 30) is a feature common to all Asian and African taxa examined. The trend towards elongation, manifest by the skull, is continued postcranially by the rela- tively high numbers of abdominal and caudal vertebrae. The emphasis on elongation of the body in these taxa, through an increase in the number of vertebrae, is also associated with considerable interspecific variation in the numbers of abdominal and caudal vertebrae (Table 5). The number of abdominal vertebrae in M. mastacembelus is 38 (p. 29) and is modal for the majority of Asian and African species. The lowest number of abdominal vertebrae recorded in any taxon is 25, in Chaudhuria and Mastacembelus aviceps and the highest 42, in M. batesii. The caudal vertebrae show a greater difference between their minimum, (36 in M. pancalus) and maximum (70 in Mastacembelus liberiensis} numbers. Many Asian taxa are distinguished by their relatively low number of abdominal and caudal vertebrae (see Table 5). These include Mastacembelus pancalus and to a lesser extent M. zebrinus, M. keithi and M. caudiocellatus and the Macrognathus species. These species are also outstanding among the mastacembeloids for the relatively greater length of their haemal and neural spines. A low vertebral count also distinguishes a number of African species including Mastacem- belus albomaculatus, M. micropectus, M. plagiostomus, M. platysoma, M. tanganicae and M. zebratus from Lake Tanganyika, and M. brachyrhinus, M. brichardi, M. crassus and M. aviceps from the lower Zairean rapids. The low vertebral number in these species is associ- ated with other reductional trends seen in the rapids fishes and the crevice- living Tanganyikan species. Other Tanganyikan species have a high vertebral count e.g. Mastacembelus cunningtoni, M. ellipsifer, M. moorii, and M. ophidium, as do many non-Tanganyikan species e.g. M. liberiensis, M. longicauda, M. loennbergii, M. ansorgii and M. cryptacanthus, and to a lesser degree such forms as M. paucispinis and the new species (Table 5). These taxa are dis- tinguished by the marked difference between the number of abdominal and caudal vertebrae, and in having a long and tapered body. In some of these species (M. moorii, M. ophidium, M. ellipsifer, and also in M. frenatus} the neural and haemal spines on the posterior caudal vertebrae (as many as the last 25) are wide and blade-like. On several occasions Mastacembelus moorii was observed swimming at approximately 10-15 m above the substrate in Lake Tanganyika (pers. obs.) and the unusual condition of the neural and haemal spines on its caudal vertebrae may possibly be a modification related to its habit of midwater swimming. The endemic Lower Zaire River mastacembeloid fauna shows a reversal of the general trend towards a greater number of caudal vertebrae seen in the African mastacembeloids. Among these Zairean species there is a decrease in numbers of caudal vertebrae from 53 in M. paucispinis to 38 in M. aviceps. Epicentral ribs occur on only the first vertebra in Chaudhuria (Fig. 2 laii) and Pillaia (Fig. 21bii), but apart from these taxa are generally found in the arrangement described in M. mastacembelus (p. 29). Epipleural ribs are confined to the fourth abdominal vertebra in M. mastacembelus (Fig. 12), an arrangement found in most Asian species although they are present on the third abdominal vertebra in Mastacembelus sinensis, and are absent in Chaudhuria and Pillaia. In the majority of African taxa epipleural ribs are confined to the fourth or fifth abdominal vertebra, but in a number of species from Lake Tanganyika, Zaire and West Africa they are absent. Interspecific variation in the pleural ribs, apart from slight variation in length, is limited to differences in the point at which the ribs first appear. Pleural ribs are absent from the first 3 abdominal vertebrae in M. mastacembelus (Fig. 12), and this arrangement is typical for most Asian taxa as well, although in Mastacembelus sinensis, M. pancalus and M. 108 R. A. TRAVERS Table 5 Number of vertebrae, spinous and branched rays in mastacembeloid taxa. Vertebrae Spinous rays Branched rays Abdominal Caudal Dorsal Anal Dorsal Anal Oriental mastacembeloid taxa Mastacembelus alboguttatus 38 47 37 3 84 83 Mastacembelus armatus 38 50 34 3 78 80 Mastacembelus caudiocellatus 37 44 34 3 68 68 Mastacembelus circumcinctus 30 47 28 3 59 68 Mastacembelus erythrotaenia 38 45 32 3 73 67 Mastacembelus guentheri 38 51 35 3 69 72 Mastacembelus keithi 31 42 32 3 54 59 Mastacembelus maculatus 32 44 26 3 56 61 Mastacembelus mastacembelus 38 47 35 3 73 75 Mastacembelus pancalus 28 36 25 3 36 41 Mastacembelus sinensis 36 44 33 3 68 65 Mastacembelus unicolor 38 48 35 3 74 77 Mastacembelus zebrinus 32 42 31 3 56 58 Macrognathus aculeatus 32 38 14 3 51 51 Macrognathus aral 32 39 21 3 55 54 Macrognathus siamensis 35 40 15 3 60 58 Chaudhuria caudata 25 46 Absent 40 42 Pillaia indie a 28 37 Absent 34 36 African mastacembeloid taxa Mastacembelus albomaculatus 38 44 37 3 65 64 Mastacembelus ansorgii 37 63 32 3 111 102 Mastacembelus aviceps 25 38 22 2 47 52 Mastacembelus batesii 42 54 33 2 78 78 Mastacembelus brachyrhinus 33 45 31 3 68 72 Mastacembelus brevicauda 40 58 30 2 86 97 Mastacembelus brichardi 32 42 29 3 57 61 Mastacembelus congicus 34 53 29 3 85 91 Mastacembelus crassus 22 44 19 2 52 61 Mastacembelus cryptacanthus 38 65 34 2 118 125 Mastacembelus cunningtoni 33 56 30 3 88 90 Mastacembelus ellipsifer 36 52 33 3 83 86 Mastacembelus flavidus 38 58 37 3 85 75 Mastacembelus flavomarginatus 39 50 27 2 75 85 Mastacembelus frenatus 40 55 35 3 78 77 Mastacembelus goro 40 49 31 3 69 72 Mastacembelus greshoffi 39 56 30 2 130 122 Mastacembelus liberiensis 33 70 28 3 131 124 Mastacembelus loennbergii 38 63 30 2 123 125 Mastacembelus longicauda 38 66 27 3 114 120 Mastacembelus marmoratus 39 50 31 3 70 66 Mastacembelus micropectus 32 50 30 3 72 78 Mastacembelus moorii 33 63 28 3 110 102 Mastacembelus niger 40 51 29 3 74 73 Mastacembelus nigromarginatus 37 56 29 2 91 82 Mastacembelus ophidium 29 66 27 1 104 108 Mastacembelus paucispinis 28 53 9 3 120 85 Mastacembelus plagiostomus 40 48 33 3 59 66 Mastacembelus platysoma 29 42 25 3 66 63 Mastacembelus reticulatus 40 56 30 2 95 92 Mastacembelus sclateri 32 52 26 3 73 75 Mastacembelus shiranus 34 - 49 29 3 79 86 MASTACEMBELOIDEI I: ANATOMICAL Table 5 Continued. 109 Vertebrae Spinous rays Branched rays Abdominal Caudal Dorsal Anal Dorsal Anal Mastacembelus signatus 32 54 29 3 80 82 Mastacembelus stappersii 38 58 33 3 82 87 Mastacembelus tanganicae 39 48 42 3 67 73 Mastacembelus vanderwaali 32 50 24 3 64 65 Mastacembelus zebratus 28 44 26 3 52 56 Mastacembelus sp. nov. 32 56 15 3 112 95 N.B. Numbers shown do not represent statistical samples. For mean number of vertebrae, spinous and branched rays in Oriental Mastacembelus species see Sufi, 1956; for frequency distribution of vertebrae and dorsal spinous rays in Macrognathus species see Roberts, 1980. maculatus ribs are only absent on the first 2 vertebrae. In the African taxa pleural ribs tend to be absent from the first 3 or 4 vertebrae, although they are wanting on the first 5 centra in M. frenatus, M. platysoma, M. vanderwaali and M. ubangensis. The greatest reduction in the number of pleural ribs, however, is seen in members of the Tanganyikan and Zairean faunas. In these species ribs are absent from as many as the first 20 abdominal vertebrae e.g. M. albomaculatus (16), M. moorii (16) and M. micropectus (14) from Lake Tanganyika, and M. brachyrhinus (20), M. brichardi (18), M. crassus (16) and M. aviceps (15) from the lower Zairean rapids. Dorsal and anal fins The morphology of the spinous and branched rays, and their supporting pterygiophores is constant in the mastacembeloids but there is considerable inter- and intra-specific variation in the total numbers of these elements (see Table 5 and Sufi, 1956 for morphometric data of Oriental species). A long row of isolated dorsal spinous rays occurs in most mastacembeloids. In M. mastacembelus 35 spines extend from the level of the fourth abdominal to the third caudal vertebrae. This posterior extension of the spines across the abdominal/caudal vertebral junction is a common mastacembeloid feature. Mastacembelus mastacembelus and several other Asian species (including M. alboguttatus, M. armatus, M. erythrotaenia, M. oatesii and M. unicolor) have high numbers of dorsal spines compared with the number in most Asian taxa (see summary of fin-ray numbers in Sufi, 1956: 108). A low number of spines does not appear to be related to the number of abdominal vertebrae (see below). The Macrognathus species are distinguished from other Asian mastacembeloids by their relatively few dorsal spines; 21 in a specimen of M. aral, 15 (plus 1 predorsal; discussed below) in a specimen of M. siamensis and 14 in a specimen of M. aculeatus (see Roberts, 1980, table 2 for frequency distributions of dorsal spine counts in Macrognathus). Although, this number is under half that in M. mastacembelus, and although Macrognathus does not have significantly fewer abdominal vertebrae or vertebrae of significantly different pro- portions, the dorsal spines in all Macrognathus species also extend across the abdominal/ caudal vertebral junction. Consequently, dorsal spines are not present above the anterior abdominal vertebrae, a characteristic feature of Macrognathus species. Spines are absent from above the first 1 8 abdominal vertebrae in the specimens of M. aculeatus and M. siamensis examined and from above the first 13 abdominal vertebrae in the specimen of M. aral (Roberts, 1980 also gives the frequency distributions of predorsal vertebral counts in Macrognathus; his table 4). Dorsal and anal spines are absent in Chaudhuria and Pillaia. 110 R. A. TRAVERS Twenty-five to 35 dorsal spines are present in the majority of African species (Table 5). Two members of the Tanganyikan fauna (Mastacembelus albomaculatus and M. flavidus) have 37 dorsal spines, and a third species, M. tanganicae has 42, the maximum number found in any mastacembeloid. The dorsal spines in the African species, regardless of their total number, originate from above the fourth, fifth or sixth abdominal vertebra, and extend across the abdominal/caudal vertebral junction. Low numbers of dorsal spines are found in several of the rapids dwelling African species (see Table 5). Mastacembelus paucispinis (as its name implies), and the undescribed species, have exceptionally few, only 9 (plus 1 predorsal) occurring in M. paucispinis and 15 in the single specimen of the new species. Their spines extend posteriorly from above about the fourth or sixth abdominal vertebrae, but do not cross the abdominal/caudal vertebral junc- tion. Associated with this exceptional arrangement of the dorsal spines there is a long rayed dorsal fin extending forward across the abdominal/caudal vertebral junction to a point close behind the last spine. The low number of dorsal spines in M. paucispinis and the undescribed species may be the result of rays not developing into spines or the result of posterior spine loss (i.e. conver- sion of spines into rays; possibly a response to life in rapids), whereas, the small number in Macrognathus (where the spines lie posteriorly and cross the abdominal/caudal vertebral border) appears to be the result of anterior spine loss. The first dorsal spine in Mastacembelus ubangensis and M. marmoratus, as well as in some West African species (e.g. M. batesii, M. brevicauda, M. flavomarginatus, M. goro, M. loennbergii, M. longicauda M. niger and M. reticulatus) is situated relatively far back along the vertebral column, at about the level of the ninth to twelfth vertebrae. DSPt NS PR CVt1 ASPt Fig. 74 Mastacembelus sinensis, abdominal/caudal vertebral junction and associated dorsal and anal spines; lateral view, left side. MASTACEMBELOIDEI I: ANATOMICAL 1 1 1 Three anal spinous rays occur in all Asian mastacembeloids (apart from Chaudhuria and Pillaid). The third anal spine in M. sinensis (Fig. 74) is equal in size to the large second anal spine. It is separated from that spine by a gap equal to 4 caudal vertebrae. This arrangement is atypical for the mastacembeloids and is found only in M. sinensis. Three anal spines also occur in the majority of African taxa. However, a single spine is characteristic of Mastacembelus ophidium, and 2 anal spines occur in the Zairean rapids' species M. crassus and M. aviceps, and in a number of west African species including, M. batesii, M. brevicauda, M. flavomarginatus, M. greshoffi, M. loennbergii, M. nigromarginatus and M. reticulatus (Table 5). A small bone (predorsal sensu Smith & Bailey, 1961), resembling the pterygiophore of a dorsal spine, is present anterior to the pterygiophore of the first dorsal spine in Macrog- nathus siamensis and in some African mastacembeloids includng M. ophidium among the Tanganyikan species, and M. batesii, M. brevicauda, M. flavomarginatus, M. greshoffi, M. loennbergii, M. marmoratus, M. nigromarginatus and M. paucispinis from western Africa. Interspecific variation in the number of branched fin rays and their supporting pterygio- phores is common. This variation may be directly related to the number of caudal vertebrae, as shown for example by Mastacembelus liberiensis which has the highest number of caudal vertebrae (i.e. 70) and also a high number of branched dorsal and anal fin rays (131 & 124, respectively). However, as a general rule, species total number of dorsal fin elements (spines and branched rays) are directly proportional to their total (abdominal and caudal) vertebrae number (see Table 5). The development of spinous rays may influence the number of branch rays in the dorsal fin in some rapids dwelling species, as shown for example by M. paucispinis in which there are 9 dorsal spines, a moderate number of caudal vertebrae (53), but a high number of branched rays (120) which extend anteriorly across the abdominal/caudal vertebral junc- tion. Apart from the undescribed species (p. 110), in no other mastacembeloid taxa were branched rays found to cross the abdominal/caudal vertebral junction. There are relatively few branched dorsal and anal fin rays (generally not exceeding more than 60 elements) in Macrognathus species. Mastacembelus pancalus also exhibits a short dorsal and anal fin and has, apart from Pillaia, the smallest number of branched rays recorded in any mastacembeloid (36 dorsal and 41 anal) as well as a low number of spinous rays (25). The low number of dorsal fin elements (spines and rays) in these taxa can be directly related to their low total vertebral number (see Table 5) and anterior loss of spines (see p. 109). Caudal fin The caudal skeleton shows considerable inter- and intraspecific variation in the topography of its elements. The arrangement found in M. mastacembelus (p. 31) is more typical of the Asian than the African taxa. To obtain an accurate appraisal of the caudal anatomy in a particular species a series of specimens was examined (where possible) in order to assay intraspecific variability. In most cases this had to be done with the aid of radiographs; it was thus not always possible to dis- tinguish finer details (e.g. whether a uroneural is fused to or merely closely associated with the urostyle). The caudal fin is distinct in the majority of Asian taxa (see Sufi, 1956), a feature dis- tinguishing them from all African species, where the caudal fin is always confluent with the posterior branched rays of the dorsal and anal fins. In those Asian species which have the caudal united with the dorsal and anal fins (e.g. Mastacembelus erythrotaenia, M. armatus, M. maculatus, M. caudiocellatus and M. circumcinctus) the caudal rays are longer than, and extend beyond the tips of, the last dorsal and anal fin rays. Thus, in effect, a distinct caudal fin is discernible. 112 R. A. TRAVERS Associated with the distinct caudal fin of the Asian species is a relatively high number of principal caudal rays (usually about 16-20). Mastacembelus pancalus (Fig. 75a) is exceptional in having only 12 fin rays despite its having a distinct caudal fin. The caudal in M. sinensis, Chaudhuria (Fig. 23a) and Pillaia (Fig. 23b) is also exceptional among Asian mastacembeloids since it is confluent with the dorsal and anal fins, and has only 8 or 9 rays. This arrangement is similar to that in the African taxa, all of which have a confluent caudal composed, in the majority of species, of 8-10 principal rays (see Figs 76, 77a & 78). Six principal caudal fin rays occur, however, in Mastacembelus batesii, M. ophidium and M. aviceps, whilst in M. zebratus there are only 4. The number of hypurals varies from 5 autogenous elements to a single autogenous fan- shaped hypural plate. The size of the hypurals in taxa with 3 or 4 elements is proportionally smaller than in those with only 2 elements, and is probably the result of hypural fusion (faint suture lines can be seen in some cases e.g. Mastacembelus congicus Fig. 76b). In the Asian species there are usually 4 or 5 hypural elements. This number is associated with the more distinct caudal fin and higher number of rays characterizing these taxa (see Figs 14, 75b & c). Mastacembelus pancalus (Fig. 75a) is exceptional in having only 2 large hypural elements (which may be correlated with the relatively low fin ray number i.e. 12) even though its caudal is distinct. Two hypural elements are otherwise found only in M. sinensis, Chaudhuria and Pillaia. The majority of African mastacembeloids have only 2 distinct hypurals (Fig. 76a & b). Three hypurals are found only in M. moorii and in the undescribed species. A single fan- shaped hypural plate distinguishes M. ellipsifer (Fig. 77a) and M. aviceps (Fig. 77b) from all other African species. U2 E1-3 U1 H3+4+5+6 AHS VCPH Ph PCR MASTACEMBELOIDEI I: ANATOMICAL 113 U2 H3 H4 H5+6 PU+U PU2 Ph H2 H1 NS Snl E1&2 HI H3+4 H5H PU+U PU2 Fig. 75 Caudal fin skeleton in (a) Mastacembelus pancalus, (b) Macrognathus aculeatus and (c) Mastacembelus erythrotaenia; lateral aspect, left side. The parhypural is autogenous and relatively large, compared with its condition in M. mastacembelus, in most taxa. It may become fused to the anterior edge of the first hypural in a number of African species (Fig. 78a & b). Generally, there is only a single uroneural apparently fused along the dorsal edge of urostylar centrum, but it is not always possible to establish whether the uroneural is fused or merely closely associated with this centrum. In addition to this element, a single unfused uroneural (uroneural 2) occurs in Macrognathus aculeatus (Fig. 75b) and Mastacembelus pancalus (Fig. 75a), as well as in a variety of African species, including most of those in Lake Tanganyika. Two uroneurals were also found in two other species, M. nigromarginatus and M. reticulatus, both from West Africa. In many Asian and African taxa (including M. maculatus, M. stappersii, M. niger and M. vanderwaali, Fig. 76a), the uroneural has a bony extension developed from its upper margin, this is equivalent to the supraneural lamina discussed by Greenwood & Rosen (1971: 14). 114 R. A. TRAVERS U1 H3+4+5+6 DP+MPt NS PU + U PUS AP+MPt AHS Ph+H1 E1 U1 U2 H3+4 H5+6 NS PU-i-U PU2 AHS VCPH Ph H1+2 Fig. 76 Caudal fin skeleton in (a) Mastacembelus vanderwaali and (b) Mastacembelus congicus; lateral view, left side. The number of epurals is also variable and ranges from a maximum of 3 to their total absence. Three epurals are found in M. pancalus (Fig. 75a) and M. unicolor but in no other species; 2 epurals occur in M. erythrotaenia, M. guentheri and Macrognathus aculeatus (Fig. 75b), with 1 in most of the remaining Asian taxa. The majority of African species have one or no epural, although M. moorii, and M. nigromarginatus have 2. The second preural vertebra contributes to the caudal skeleton in a number of mastacem- beloids. The haemal arch of this vertebra is autogenous in the majority of Asian taxa (M. mastacembelus, Fig. 14; M. erythrotaenia, Fig. 75c; and Macrognathus species, Fig. 75b). Its long haemal spine extends posteriorly to lie along the anterior edge of the parhypural, and its tip contributes to the support of the ventral caudal fin rays. In Chaudhuria (Fig. 23a) and Pillaia (Fig. 23b) the haemal arch is fused to the second preural vertebra and has a short haemal spine which does not contribute to the support of the caudal fin rays. MASTACEMBELOIDEI I: ANATOMICAL 115 NS PU+U PU2 PU3 PU+U PU2 HS Ph Fig. 77 Caudal fin skeleton in (a) Mastacembelus ellipsifer, and (b) Mastacembelus aviceps; lateral view, left side. The haemal spine is short, non-ray supporting, and its arch fused to the second preural vertebra in the majority of African taxa (see Figs 76a, 77 & 78). In Mastacembelus congicus (Fig. 76b) however, the haemal spine is ray-supporting, and extends from an autogenous haemal arch in a manner similar to that of most Asian taxa. Squamation Small, cycloid scales cover the body, apart from the dorsal surface of the head in the majority of mastacembeloids. In some Asian taxa (e.g. Mastacembelus pancalus) the dorsal surface of the head is also covered in scales. Chaudhuria and Pillaia among the Asian species, and Mastacembelus latens, (Roberts & Stewart, 1976: 307), M. crassus, and M. aviceps among the African taxa are completely scale- 116 R. A. TRAVERS a E1 U1 H5+6 H3+4 DP+MPt Snl NS PU+U PU2 AHS AP+MPt Ph ADPt H1 E1 U2 U1 DP+MPt H 3 +4+5+6 NS PU2 VCPH AP+MPt Ph+HI+2 ADPt Fig. 78 Caudal fin skeleton in (a) Mastacembelus shiranus and (b) Mastacembelus frenatus; lateral aspect, left side. MASTACEMBELOIDEI I: ANATOMICAL 117 less. An intermediate state between the modal condition and that found in these taxa occurs in Mastacembelus micropectus. Here, only the posterior third of the body is scaled. Myology of Mastacembelus mastacembelus Cephalic muscles Group one muscles The massive size of the adductor musculature, in comparison with the relatively small neurocranial, jaw and hyopalatine bones, is probably an indication that the mastacembeloid jaws are capable of powerful biting actions. LAP AAP tA, HyoAdd HyoAdd AO DO LAP AAP Tl Com RMT Fig. 79 Mastacembelus mastacembelus, (a) superficial cephalic muscles, tendons and ligament after removal of the skin and eyeball, and (b) deep cephalic muscles and tendons after removal of parts A, and A2 of the adductor mandibulae muscle and the levator operculi muscle; lateral view, right side. 118 R. A. TRAVERS Four subdivisions of the adductor mandibulae (Ai; A2; A 3 & Aw) are present in Mastacem- belus mastacembelus. A ligament (Fig. 79a) passes superficially across the anterior region of the adductor mandibulae, from the lateral edge of the anguloarticular facet to the ventro- medial face of the large 1st infraorbital bone. A small subdivision of this ligament passes from its ventral end below the adductor anterior tendon (tA,) to attach to the mass of con- nective tissue on the posteromedial face of the maxilla (between it and the lateral face of the coronoid process). Although somewhat displaced, this ligament is thought to be homologous with the maxillo-mandibular ligament recently discussed by Stiassny (1981: 283). Part AI of the adductor mandibulae (Fig. 79a) originates from the lateral face of the preoperculum (horizontal arm), symplectic, quadrate and posterolateral face of the angulo- articular. It is the smaller of the superficial adductor elements, and lies ventral to part A2. A wide tendon (tAi) extends anteriorly from the lateral face of AI and inserts along the ventrolateral margin of the maxilla and dorsal surface of the premaxilla. An inner slip of muscle fibres from the anteromedial face of AI insert musculously on the lateral face of the tendinous anterior end of the A2 division. Part A2 forms the main mass of the superficial adductor musculature in M. mastacembelus (Fig. 79a). It lies dorsal to AI and curves anteriorly around the posteroventral edge of the orbit. The medial fibres of A2 originate ventrally from the lateral face of the preoperculum (vertical arm), hyomandibula, symplectic, quadrate and coronomeckelian, and dorsally from the dorsolateral edge of the parietal, pterotic and frontal. A2 is composed of two sections distinguished anteriorly by their separate tendons and sites of insertion. The upper sec- tion A2p (Fig. 79a) constitutes the bulk of the muscle, its fibres merging anteriorly onto a short, broad tendon that inserts on the posterodorsal edge of the coronoid process. The smaller lower section, A2a (Fig. 80) has a narrow tendon which passes medially to merge with a wide aponeurosis on part Aw of the adductor complex. The truncus hyomandibularis part of the Vllth cranial nerve emerges from the ventral hyomandibular foramen below the level of the dorsal margin of A2 and runs anteriorly across its medial face before passing below the quadrate. A2 is separated from the deeper part (A3) of the adductor mandibulae by the levator arcus palatini muscle. Part A3 lies medial to the levator arcus palatini and is separated from it by a thin sheet of connective tissue. This broad muscle originates, ventrally, from the dorsolateral face of AwApo Fig. 80 Mastacembelus mastacembelus, lower jaw and associated musculature; medial aspect, right side. MASTACEMBELOIDEI I: ANATOMICAL 1 19 the suspensorium (including the lateral face of the hyomandibula, quadrate, metapterygoid and endopterygoid) and dorsally from the precommissural lateral wall of the neurocranium (including the sphenotic, prootic, pterosphenoid and descending frontal lamina). The fibres course ventrorostrally, merging into a strong tendon (tA3) that runs across the somewhat bulbous anterolateral face of the ectopterygoid (Fig. 79b). The tendon appears to have ossi- fied in this region, possibly contributing to the unusually large coronomeckelian (Travers, 1984). The anterior tip of the coronomeckelian is connected tendinously (tA3) to the medial face of the meckelian fossa — along the posterodorsal edge of Meckel s cartilage. The minus mandibularis of the trigeminal nerve branches from the truncus infraorbitalis medial to A3, and passes ventrorostrally along the ventral edge of tA3 and the long coronomeckelian. Part Aw (Fig. 80) originates from the medial face of the mandible (including the angulo- articular, retroarticular and ventromedial margin of the dentary). Its fibres converge on a medial tendinous aponeurosis which is consolidated adjacent to the anguloarticular facet. This aponeurosis inserts on the anteromedial margin of the quadrate, just below the postero- medial process of the ectopterygoid. The levator arcus palatini (Fig. 79b) is a thin sheet compressed between the dorsal region of A2 and A3; it originates along the dorsolateral edge of the neurocranium (pterotic and frontal), with its posterior fibres stemming from the postorbital process of the sphenotic. The muscle runs vertically to insert musculously on the lateral face of the suspensorium, including the ventrolateral face of the hyomandibula and metapterygoid, and the dorsolateral face of the symplectic. It narrows posteriorly and its fibres intermix with the anterior fibres of the dilatator operculi. The dilatator operculi (Fig. 79a) lies posterior to the levator arcus palatini. The lateral face of the dilatator is partly covered by the posterodorsal edge of adductor mandibulae A2 and the upper arm of the preoperculum. It originates from the lateral face of the pterotic (above its hyomandibular fossa) and from the posterolateral margin of the sphenotic ventral to the postorbital process. Its fibres converge across the lateral face of the posterior hyoman- dibular condyle, and merge into a short tendon inserting firmly on the dorsal surface of a prominent dilatator process of the operculum. Group two muscles The levator operculi (Fig. 79a) is a comparatively large and ovoid muscle originating from the posterolateral face of the pterotic dorsal to the posterior end of the hyomandibular con- dyle. The dorsomedial face overlies the upper region of the adductor operculi. Ventral to this the medial face overlies the notched dorsal edge of the operculum, posterior to the opercular facet, and inserts musculously on the dorsolateral face of this bone. The ventral edge of the levator inserts along the narrow dorsal surface of the opercular ridge. This promi- nence separates it from a distinct muscle-the 'musculus intraopercuW (discussed below)-on the ventrolateral face of the operculum. The latter muscle originates on the posterolateral edge of the preoperculum, and inserts musculously on the adjacent lateral face of the oper- culum, ventral to the operculum ridge (Fig. 79a). There is no connection between this muscle and the levator operculi in M. mastacembelus (see p. 120). The adductor operculi (Fig. 81) is a relatively small muscle covered, in lateral view, by the levator operculi and the operculum. It originates tendinously from the dorsolateral face of the exoccipital at a point below the posterior end of the pterotic facet for the hyoman- dibula. Its fibres expand ventrocaudally from a dorsal apex to insert musculously on the medial face of the operculum. The fibres along the posterior margin of the adductor inter- mingle with those from the dorsolateral region of the hyohyoidei adductores (discussed below). Between the anteromedial margin of the adductor operculi and the posterior edge of the adductor hyomandibulae is a pseudobranch (Bhargava, 1953). The buccal face of the pseudobranch lies just above the integumentary lining of the pharynx in a lateral recess in the dorsomedial face of the hyomandibula (Fig. 8 1 ). 120 R. A. TRAVERS Ex PrAP AAP Met HyoAdd Fig. 81 Mastacembelus mastacembelus, deep cephalic adductor musculature after removal of the jaws, opercular series, hyomandibula and associated superficial cranial muscles; lateral view, right side. The adductor hyomandibulae (Fig. 81) is well developed. Since it is apparently formed from the anterior fibres of either the adductor operculi or the adductor arcus palatini (Winter-bottom, 1974), it is considered as a group two derivative. The adductor hyomandibulae originates from the surface of the parasphenoid posterior to the lateral commissure. Fibres also originate from the border of the parasphenoid with the prootic in this region, and from the ventral surface of the small otic bulla in the prootic. The internal carotid foramen ventral to this bulla is covered by the adductor hyomandibulae. The muscle expands ventrally, and its lateral fibres insert on the ventromedial face of the hyomandibula. An anteroventral muscle slip extends below the posterior end of the adductor arcus palatini to insert musculously on the dorsomedial margin of the symplectic. The adductor arcus palatini (Fig. 81) is an enlarged muscle extending along the side of the neurocranium from below the trigeminofacialis chamber to the lateral ethmoid. It orig- inates mainly along the lateral face of the parasphenoid, from its anterior end (below the lateral ethmoid) to a point ventral to the lateral commissure. Fibres of the adductor also originate from the narrow lateral face of the basisphenoid and the ventrolateral face of the prootic, between the lateral commissure and the tip of its anterior process. The ventral sur- face of this process is trough-like, thus increasing the area available for muscle attachment. The adductor arcus palatini extends between its area of origin and the dorsomedial face of the suspensorium. A series of small tendons from within the muscle merge into an aponeurosis that inserts on the posterior end of the endopterygoid. Apart from these tendons, the adductor inserts musculously on the dorsomedial face of the metapterygoid, the dorsal edge of the endopterygoid and ectopterygoid, and anteriorly, on the dorsal surface of the flattened suborbital region of the palatine. A number of other myological features warrant description; not least of these is the distinct muscle (already noted; p. 119) originating from the posterior edge of the preoperculum and inserting on the lateral face of the operculum, ventral to the operculum ridge (Fig. 79b). The fibres of this muscle do not appear to intermingle with those of any other muscles in this region. It is innervated by a branch of the truncus hyomandibularis (Vllth.). Winterbottom's MASTACEMBELOIDEI I: ANATOMICAL 121 Sc PtT Hyo Add HyoAbd Fig. 82 Mastacembelus mastacembelus, hyohyoidei adductores muscle after removal of the opercular series; lateral view, right side. (1974) synonymy gives no clue to the identity of this muscle. In view of its position within the opercular series I have named it the 'musculus intraopercuW. The presence of this muscle (possibly derived from the hyohyoidei adductores; see Travers, 1984) may be correlated with the restricted opercular opening in M. mastacembelus, and thus the need for an atypical method of expanding the branchial chamber. The hyohyoidei adductores (Fig. 82) are large in M. mastacembelus. This muscle is innervated by the ramus hyoideus (part of the truncus hyomandibularis of VII), and lies anteriorly as a sheet of fibres between the distal parts of the branchiostegal rays. From there it extends dorsally above the last branchiostegal ray and continues around the dorsal margin of the operculum. The operculum partly overlies this dorsolateral expansion of the hyohyoidei adductores, whose lateral fibres are loosely connected to the medial face of the bone by a thin fascia. The dorsomedial face of the hyohyoidei adductores (above the opercu- lum) inserts musculously along the lateral epaxialis musculature. The anterior edge of the muscle borders the adductor operculi, and there is some intermingling of their fibres. Poster- iorly, the hyoidei inserts along the dorsolateral face of the cleithrum, the lateral face of the supracleithrum and the ventral margin of the posttemporal tubules (Fig. 82). The insertion of the muscle along the postcranial sensory canal marks its upper edge. This dorsal encroach- ment of the hyohyoidei adductores is responsible for the restricted opercular opening in M. mastacembelus. The hypaxial musculature is considered to be composed of the dorsal obliquus superioris and the ventral obliquus inferioris by Winterbottom (1974). 122 R. A. TRAVERS Epax Ex ObSup Fig. 83 Mastacembelus mastacembelus, epaxial musculature insertion on the basicranium and position of Baudelot's ligament; lateral aspect, right side. The obliquus superioris (Fig. 83) has a particularly prominent point of insertion on the basicranium. The muscle tapers anteriorly from its posterior position along the ventrolateral wall of the body, the fibres merging into a strong aponeurosis adjacent to the medial face of the cleithrum. The aponeurosis passes along the ventral surface of the epaxial muscula- ture, but is separated from it by the fascia covering the muscles. Anteriorly, the aponeurosis narrows into a strong tendon that inserts on the posteroventral base of the exoccipital, above its ventral border with the basioccipital. Baudelot's ligament is small (Fig. 83), is closely associated with the prominent anterior tendon- of the obliquus superioris, and is discernible only after careful dissection. It crosses the dorsal surface of the obliquus between its anterior connection to the basioccipital and its posterior connection to the pectoral girdle. The ligament attaches anteriorly to a shallow fossa on the posterior edge of the basioccipital, medial to the large obliquus tendon. A dense mass of adipose connective tissue in this region of the basicranium connects Baudelot's liga- ment to the obliquus superioris tendon. From its connection to the basioccipital the ligament runs posteriorly across the obliquus tendon and, anterior to the pectoral girdle, divides into an upper arm attaching to the ventromedial face of the supracleithrum, and a lower arm attaching to the dorsolateral face of the cleithrum. Comparative myology of the Mastacembeloidei Group one and two cephalic muscles in the majority of Asian and African mastacembeloids were examined and compared with those in M. mastacembelus. Unfortunately, this compari- son only includes the most superficial muscles in specimens of Chaudhuria and Pillaia, partly because of their small adult size and partly because none could be serially sectioned. Cephalic muscles Group one muscles The position and size of the maxillo-mandibular ligament in M. mastacembelus (Fig. 79a) is typical of that in the majority of mastacembeloids, including Chaudhuria and Pillaia. However, in two Tanganyikan species (Mastacembelus albomaculatus and M. micropectus Fig. 84a) and three from the lower Zairean rapids (Mastacembelus brichardi, Fig. 84b, M. MASTACEMBELOIDEI I: ANATOMICAL 123 LAP AAP tA2p tAi Hyo Add Ai MmLig HyoAdd Fig. 84 Lateral view of the right superficial cephalic muscles, tendons and ligament after removal of the skin and eyeball, in (a) Mastacembelus micropectus and (b) Mastacembelus brichardi. crassus and M. aviceps) the ventral attachment of the ligament is covered by the hypertro- phied superficial adductor musculature. The maxillo-mandibular ligament is relatively narrow in Mastacembelus moorii (Fig. 85), and only attaches to the anterior end of the 1st infraorbital bone. The ligament is absent in Mastacembelus sinensis, M. zebrinus, M. pancalus and all Macrognathus species (Fig. 86a-c). Interspecific variation in the morphology of the adductores mandibulae and their associ- ated tendons is particularly noticeable in the superficial parts of that muscle complex. The ventral position of A^ is a diagnostic feature of all mastacembeloids. It is smaller than 124 R. A. TRAVERS A2 in most taxa although some Asian species are exceptional. In the Macrognathus species (Fig. 86a), Mastacembelus pancalus (Fig. 86b) and M. zebrinus (Fig. 86c) A] is the largest element of the adductor complex. In these taxa it extends dorsal ly over the ventrolateral face of A2, the upper edge lying on a level with the centre of the eye, and the large size of Aj may be associated with the lack of the maxillo-mandibular ligament. Also, in these species the lateral fibres converge onto a sheet-like aponeurosis which is consolidated into a particu- larly long strap-like i\\ tendon. Part A! is also relatively large in a number of Tanganyikan and Zairean species (but does not exceed A2 in size), and is a reflection of the generally hypertrophied adductor muscula- ture in these species (see below). LAP AAP tAi MmLig Fig. 85 Mastacembelus moorii, superficial adductor mandibulae muscle, tendons and associated ligament after removal of the skin and eyeball; lateral aspect, right side. The inner slip of muscle originating from the anteromedial face of A] inserts musculously on the lateral face of the anterior tendinous part of A2 in all mastacembeloid taxa. Aj is small in Mastacembelus moorii (a Lake Tanganyikan species; Fig. 85), and has a restricted origin from the ventrolateral face of the quadrate, the anteroventral face of the preoperculum, and from the anguloarticular. In this species A2 is large and originates from the lateral face of the symplectic and most of the preoperculum and quadrate. The dorsolateral position of A2 and its subdivision into two subsections (A2a and A2p) inserting tendinously on, respectively, the coronoid process and posterior tendon of Aw, are characteristic features of the superficial adductor musculature in all Asian and African mastacembeloids. A2 is exceptionally small in Macrognathus species, Mastacembelus pancalus and M. zebrinus (Fig. 86a-c), a feature combined with the enlarged Aj in these taxa, and which may be correlated with the size and shape of the coronoid process (Travers, 1984). The postero- dorsal fibres of A2 in these taxa barely cover the levator arcus palatini. The fibres merge ventrorostrally and extend below the orbit, grading into a long strap-like tendon (tA2). This tendon divides anteriorly, the small medial subsection (tA2a) inserting on the posterior aponeurosis of Aw, the larger lateral subsection (tA,p) inserting on the lateral face of the broad, low coronoid process and on the dorsolateral face of the dentary. MASTACEMBELOIDEI I: ANATOMICAL 125 The dorsal fibres of A2 originate above the upper edge of the levator arcus palatini and part A3, in the two Tanganyikan species Mastacembelus moorii and M. ophidium. The dorsal surface of the skull in these species is relatively narrow, and the expanded A2 fibres originate from its dorsolateral margin. The adductor muscles, particularly A2, are hypertrophied to an unparalleled extent in the microphthalmic and cryptophthalmic mastacembeloids. Pillaia (from Asia; Fig. 87), Mastacembelus micropectus and M. albomaculatus (Lake Tanganyika; Fig. 84a) and M. brachyrhinus, M. brichardi, M. crassus, M. aviceps and probably M. latens (from the lower Zairean rapids; Fig. 84b). The adductor musculature in Mastacembelus brichardi was described by Poll (1973). This species is markedly cryptophthalmic and its reduced eyes lie below A2 and the levator arcus palatini. In all the cryptophthalmic and microphthalmic taxa the roof of the skull slopes ventrally and the massive A2 originates from the dorsal surface of the frontal postorbitally, and from the entire dorsal surface of the parietal. The dorsomedial face of each A2 contacts its partner in the midline (their fibres not interconnecting) in all but Pillaia and M. brachyrhinus, in these species A2 is not hypertrophied to such an extreme extent as it is in the others. Part A3 of the adductor mandibulae lies medial to the levator arcus palatini and has a similar origin and insertion in all mastacembeloids (p. 1 1 8). The size of the coronomeckelian is an indication of the size and strength of the A3 muscle and its anterior tendon (tA3). The extent to which the tendon of A3 ossifies varies widely among the Asian and African taxa, (see above p. 80). Part Aw shows no marked departure from the condition described for M. mastacembelus (p. 119). In all species the levator arcus palatini lies between divisions A2 and A3 of the adductor mandibulae; it originates from the dorsolateral edge of the neurocranium and inserts muscu- lously along the dorsolateral face of the suspensorium. The levator fibres merge ventrally into a wide, transparent, sheet-like aponeurosis which is particularly thin in a number of Asian (e.g. Mastacembelus sinensis and M. armatus) and African species (e.g. M. frenatus, M. moorii and M. batesii). This condition of the levator appears to have a mosaic distribution among the mastacembeloids. The posterodorsal fibres intermingle with those from the anterior margin of the dilatator operculi in all taxa. The ventral apex of the dilatator operculi inserts tendinously on the dorsal surface of the opercular dilatator process in all mastacembeloids. The extent to which the lateral face of the dilatator is covered by the preoperculum and the A2 division of the adductor mandibulae depends on the degree to which the latter are developed. In those species with a protracted vertical arm of the preoperculum, for example M. longicauda and M. reticulatus, the lateral face of the dilatator is completely covered, as it is in those species with a particularly massive A2 muscle (p. 87 & Fig. 84). Group two muscles The levator operculi shows little interspecific variation apart from slight differences in rela- tive size. The muscle insertion on the dorsolateral face of the operculum, is a characteristic feature of all mastacembeloids. A large levator, (relative to its size in M. mastacembelus) occurs in M. albomaculatus; its ventrolateral fibres traverse the low opercular ridge in this species, and intermix with the dorsolateral fibres of the 'intraoperculC muscle. The morphology of the adductor operculi also shows little interspecific variation. The fibres along the posterior margin of the muscle intermingle, in all species, with the dorso- lateral part of the hyohyoidei adductores in a manner similar to that described in M. masta- cembelus (p. 1 19). The pseudobranch lies between the posteromedial margin of the adductor operculi and anteromedial face of the adductor hyomandibulae in all the species investigated. There is little interspecific deviation of the adductor hyomandibulae; it is particularly well- developed in all mastacembeloids. The muscle originates from the posteroventral region of 126 R. A. TRAVERS the parasphenoid and prootic (including the ventral surface of the otic bulla), and inserts on the medial face of the symplectic and hyomandibula (Fig. 81). The marked interspecific variation in the arrangement of the adductor arcus palatini muscle involves, posteriorly, its site of origin along the ventrolateral face of the braincase, and anteriorly, its connection to the enlarged 1st infraorbital bone. The anterior region of the adductor arcus palatini, compared with its condition in M. mastacembelus (Fig. 81), is modified in a number of Asian taxa including the Macrognathus species, Mastacembelus pancalus, M. zebrinus, M. keithi, M. caudiocellatus and M. maculatus (see Figs 86 & 88). The anterior fibres of the muscle in these taxa extend from the anterolateral face of the paras- phenoid across the ectopterygoid to insert musculously along the posterior edge of the 1 st infraorbital. In M. zebrinus (Fig. 88a) this extension is little more than the lengthening of the anterolateral fibres of the adductor which form the orbital floor. However, in Macro- gnathus (particularly M. aculeatus; Fig. 88b) the anterior region of the adductor arcus pala- tini is unconnected to the fibres which form the orbital floor, apart from some slight contact along the anteromedial margin. The medial end of this virtually distinct anterior muscle in Macrognathus aculeatus is connected, tendinously, to the anterior end of the parasphenoid along its dorsolateral margin. The muscle fibres extend anterolateral ly around the edge of the orbital cavity, crossing but not connecting to the anterodorsal face of the ectopterygoid. The anterior end of the fibres in this region merge into a broad aponeurosis which inserts on the attenuated posterior edge of the 1st infraorbital (Fig. 4 la). This anterior differentiation of the adductor arcus palatini may be correlated with the large rostral appendage in the species involved. The uniquely trunk-like rostral appendage in Macrognathus, where the muscle is found in its most highly developed form, lends support to this view. Contraction of the anterior adductor would result in movement of the large 1 st infraorbital bone which contributes to the complex musculo-skeletal system that governs the movement of the highly mobile rostral appendage in these taxa. a AAP Int HyoAdd MASTACEMBELOIDEI I: ANATOMICAL 127 LO DO AAP tA] Int Hyo Add Tl tA2p LO DO A2 LAP AAP Tl tA2p tA, AI Int Hyo Add Fig. 86 Lateral view of the right superficial cephalic muscles, after removal of the skin and eyeball, in (a) Macrognathus aculeatus, (b) Mastacembelus pancalus and (c) Mastacembelus zebrinus. 128 R. A. TRAVERS A2 HyoAdd Fig. 87 Pillaia indica, superficial cephalic muscles after removal of the skin; lateral view, right side. The anterior fibres of the adductor arcus palatini do not insert on the posterodorsal surface of the palatine in Mastacembelus armatus or Mastacembelus erythrotaenia and hence do not form the orbital floor in these species. The adductor arcus palatini originates posteriorly, in the majority of mastacembeloids, along the ventrolateral face of the prootic and ventral surface of its anterior process (as described in M. mastacembelus p. 1 20). The lack of a long anterior prootic process in some species results in a smaller area available for the origin of the adductor. The absence of this process may be associated with the presence of only a relatively small rostral appendage and the lack of an enlarged anterior region of the adductor in these species (e.g. Mastacembelus tanganicae p. 6 1 ). The need to provide an increased area of origin for the long adductor arcus palatini is probably a further factor influencing the development of the anterior process on the prootic generally found in mastacembeloids. Of the other myological features; the 'musculus intraoperculi' (p. 121) is a unique charac- teristic of all mastacembeloids. In the majority of taxa its fibres are unconnected to those of any other cephalic muscle (Figs 79a & 84-87). The hyohyoidei adductores shows little interspecific variation in their arrangement. The dorsolateral expansion of the muscle, and its musculous insertion on the cleithrum, supra- cleithrum and posttemporal tubules are features common to all taxa, including Chaudhuria and Pillaia. This branchiostegal muscle is responsible for restricting the opercular opening since it extends over, and is inserted on, the ventrolateral face of the epaxialis musculature. The obliquus superioris is similar in all mastacembeloids, and its anterior tendinous inser- tion on the posteroventral face of the exoccipital is a characteristic feature of the group. The wide anterior tendon inserts laterally in a shallow basioccipital fossa medial to which the basioccipital accommodates the anterior end of Baudelot's ligament. A small, relatively weak Baudelot's ligament, as described in M. mastacembelus (p. 122), is present in all taxa. It is closely connected to the large anterior obliquus tendon ventrally, and with the ventral surface of the epaxialis musculature dorsally. In most species the liga- ment crosses the dorsal surface of the obliquus tendon before attaching to the pectoral girdle. However, in Mastacembelus longicauda it crosses ventrally, below the tendon. A divided posterior end of Baudelot's ligament, inserting on both the cleithrum and the supracleithrum, is also a feature common to all mastacembeloids. MASTACEMBELOIDEI I: ANATOMICAL 129 PrAP OlfT LE PrAP OlfT AAP LE Tl Met Ect End Fig. 88 Lateral view of the right adductor arcus palatini muscle in (a) Mastacembelus zebrinus, and (b) Macrognathus aculeatus. 130 R- A. TRAVERS Acknowledgements I am indebted to the Trustees of the British Museum (Natural History) and the Keeper of Zoology for access to the collections and research facilities. I acknowledge the assistance given me by Professor J. D. Pye (and staff in the Department of Zoology and Comparative Physiology, Queen Mary College) in whose department this study was initiated and I particularly thank Dr D. R. Kershaw for supervision and my initial introduction to the Fish Section at the British Museum (Natural History). It is with great pleasure that I extend my sincere thanks and gratitude to the staff in the Fish Section (and all associated with it), under whose guiding influence I was fortunate enough to fall. In particular I thank Dr P. H. Greenwood (not least for his role as mentor and critic of an earlier draft) and Gordon Howes for their time and inspiring discussions. Financial support from Queen Mary College (Drapers' Studentship) and the University of London (University Studentship) is also acknowledged with gratitude as is the Central Research Fund (Univ. of Lond.) and Godman Exploration Fund (BM[NH]) for financing fieldwork in East Africa. Loans and gifts of specimens for this study were generously donated by: Dr P. H. Skelton (AM); Dr T. R. Roberts (CAS); Dr Hsien-Wen (IHW-h, China); Dr C. C. Swift (LACM); Prof K. F. Liem (MCZ); Dr D. Thys van den Audenaerde (RG) and Drs K. C. Jayaram & G. M. Yazdani (ZSI). Finally, my parents Duilio and Helen Travers deserve special mention for without their active encouragement and support, over many years, this would surely not have been possible. To them and Kath I extend my warmest thanks. References Agrawal, V. P. & Dalela, R. C. 1 966a. 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The interarcual cartilage; a review of its development distribution and value as an indicator of phyletic relationships in euteleostean fishes. /. Nat. Hist. 15 : 853-871. 1984. A review of the Mastacembeloidei, a suborder of synbranchiform teleost fishes. Part II; Phylogenetic analysis. Bull. Br. Mus. nat. Hist. (Zool). 47 (1). Publication 28 June 1984. Wheeler, A. C. 1956. The type species of Mastacembelus and the second edition of Russell's 'Natural History of Alleppo.' Bull. Raffles Mus. No. 27 : 91-92. Whitehouse, R. H. 1918. The caudal fin of the eel Chaudhuria. Rec. Indian Mus. 14 : 65-66. Winterbottom, R. 1974. A descriptive synonymy of the striated muscles of the Teleostei. Proc. Acad. nat. Sci. Philad. 125 (12) : 225-317. Yazdani, G. M. 1972. A new genus offish from India. J. Bombay nat. Hist. Soc. 69 (1) : 134-135. Yazdani, G. M. 1975. Fishes of Khasi Hills Meghalya (India), with observations on their distributional pattern. /. Bombay, nat. Hist. Soc. 74 : 17-28. 1976a. The upper jaw of Indian hill-stream eel Pillaia indica, Yazdani (Perciformes: Mastacembe- loidei). Bull. Zool. Surv. India. 2:213-214. 19766. A new family of mastacembeloid fish from India. J. Bombay nat. Hist. Soc. 73 (1): 166-170. — 1978. Adaptive radiation in the mastacembeloid fishes. Bull. Zool. Surv. India. 1 (3): 279-290. Manuscript accepted for publication 9 March 1983 British Museum (Natural History) Tilapine fishes of the genera Sarotherodon, Oreochromis and Danakilia Dr Ethelwynn Trewavas The tilapias are cichlid fishes of Africa and the Levant that have become the subjects of fish-farming throughout the warm countries of the world. This book described 41 recognized species in which one or both parents carry the eggs and embryos in the mouth for safety. Substrate-spawning species, of the now restricted genus Tilapia, are not treated here. Three genera of the mouth-brooding species are included though in one of them, Danakilia, the single species is too small to warrant farming. The other two, Sarotherodon, with nine species, and Oreochromis, with thirty-one, are distinguished primarily by their breeding habits and their biogeography, supported by structural features. Each species is described, with its diagnostic features emphasised and illustrated, and to this is added a summary of known ecology and behaviour. Conclusions on relationships involve assessment of parallel and convergent evolution. Dr Trewavas writes with the interests of the fish culturists, as well as those of the taxonomists, very much in mind. 580pp, 1 88 illustrations include halftones, diagrams, maps and graphs. Extensive bibliography. Publication 24 November 1 983. £50 0 565 00878 1 Publications Sales British Museum (Natural History) Cromwell Road London SW7 5 BD England Titles to be published in Volume 46 A review of the Mastacembeloidei, a suborder of synbranchiform teleost fishes Part I: Anatomical descriptions. By Robert A. Travers A review of the spider subfamily Spartaeinae nom. n. ( Araneae: Salticidae) with descriptions of six new genera. By F. R. Wanless The family Nannastacidae (Crustacea: Cumacea) from the deep Atlantic. By N. S. Jones Miscellanea Printed in Great Britain by Henry Ling Ltd . at the Dorset Press. Dorchester, Dorset / Bulletin of the V British Museum (Natural History A review of the spider subfamily Spartaeinae nom. n. (Araneae: Salticida< with descriptions of six new genera F. R. Wanless Zoology series Vol 46 No 2 23 February 1984 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), 1984 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 ISBN 0565 05001 X ISSN 0007-1498 Zoology series Vol46No. 2pp 135-205 British Museum (Natural History) Cromwell Road London SW7 5BD Issued 23 February 1984 (^ A review of the spider subfamily Spartaeinae nom. i,3RARy n. (Araneae: Salticidae) with descriptions of sixjiew op n p r ft >^X \~\ \ ]3 n gciicru v^^^T^ITc F. R. Wanless Department of Zoology, British Museum (Natural History), Cnjjnwefl Road, Lor SW7 5BD Contents Synopsis Introduction 136 Morphological characters 137 The subfamily Spartaeinae 141 Remarks 141 Definition 141 Diagnosis 142 Affinities 142 Key to genera 1 46 The genus Spartaeus 147 Definition 148 Diagnosis 148 The genus Yaginumanis 1 52 Definition 152 Diagnosis 153 The genus Taraxella 155 Definition 155 Diagnosis 155 The genus Mintonia 157 Definition 157 Diagnosis 158 Key to species 158 The genus Gelotia 169 Definition 169 Diagnosis 170 Key to species 1 70 The genus Cocalus 1 80 Remarks 180 The genus Brettus 181 Remarks 181 The genus Neobrettus 181 Definition 181 Diagnosis 183 The genus Cyrba 185 Remarks 185 The genus Meleon 186 Definition 186 Diagnosis . . ^ 187 The genus Veissella 189 Definition . 189 Diagnosis 190 Bull. Br. Mus. nat. Hist. (Zool.) 46 (2): 135-205 Issued 23 February 1984 135 136 F. R. WANLESS The genus Phaeacius . . . . 190 Remarks . . . . . . . . . . . . . . 190 The genus Portia . . . .,, 191 Definition ..... . .192 Diagnosis .192 Remarks 192 Taxonomic summary . . . .194 Check list, known sex and distribution of species 194 Acknowledgements . . . v .196 References 196 Synopsis The spider subfamily Spartaeinae nom. n., is defined; a key to genera and species check list are pro- vided. Morphological characters and generic affinities both fossil and recent are discussed. Six new genera, Meleon, Mintonia, Neobrettus, Taraxella, Veissellaand Yagin uman is are proposed. Spartaeus Thorell and Gelotia Thorell are revised. Distributional data are given and separate keys to the species of Gelotia and Mintonia are provided. The genera Cocalus Koch, Cyrba Simon, Phaeacius Simon, Portia Karsch and Veissella are illustrated by figures of selected species. All the known species of Gelotia, Mintonia, Neobrettus, Spartaeus, Taraxella, Yaginumanis, the newly discovered males of Brettus anchorum Wanless and Meleon solitaria (Lessert) are figured and described. The type material of 1 2 nominate species was examined and seven lectotypes designated. One generic and three specific names are synonymised, and seven new combinations are proposed. Introduction This study completes a preliminary revision of recent salticids formerly included in the sub- family Boethinae. Unfortunately the nominate genus Boethus Thorell, 1878 is a junior homonym of Boethus Foerster, 1868 and a new subfamily name (Spartaeinae) must be proposed. However, as a result of synonymy (see p. 148) the type species remains unchanged. Simon (1901) stated that Boethus appeared to be transitional between Lyssomanes Hentz, Cocalodes Pocock and Linus Peckham & Peckham ( = Portia Karsch) and proposed the sub- group Boetheae comprised of two genera, Boethus and Portia. Petrunkevitch (1928) subsequently reorganised the subgroup by elevating Boetheae to subfamily rank to include salticids characterised by their fairly large posterior median eyes. Roewer (1954) adopted Petrunkevitch's system, but divided the subfamily into five groups (Table 1). Of the genera listed, three, Cocalodes (revised Wanless, 1982), Sonoita Peckham & Peckham and Holcol- aetis Simon, are removed from the Spartaeinae because the male palps possess a median apophysis (see below). The systematic position of a fourth genus Tanna Berland is uncertain Table 1 List of genera in the subfamily Spartaeinae (sensu Roewer, 1954) Gr. Boetheae 3. Gr. Lineae Boethoportia Hogg Linus Peckham & Peckham Boethus Thorell Tanna Berland Portia Karsch 4. Gr. Cocalodeae Gr. Cocaleae Cocalodes Pocock Cocalus Koch Sonoita Peckham & Peckham Phaeacius Simon 5. Gr. Holcolaeteae Holcolaetis Simon SPIDER SUBFAMILY SP ART AEINAE 137 Table 2 Revised list of genera in the subfamily Spartaeinae RECENT Brettus Thorell Neobrettus gen. n. Cocalus Koch Phaeacius Simon Cyrba Simon Portia Karsch Gelotia Thorell Spartaeus Thorell Meleon gen. n. Taraxella gen. n. Mintonia gen. n. Veissella gen. n. Yaginumanis gen. n. FOSSIL Almolinus Petrunkevitch Eolinus Petrunkevitch Cenattus Petrunkevitch Paralinus Petrunkevitch Prolinus Petrunkevitch as the male palpal organs are of a relatively simple euophryine type and show no affinities with other genera listed in the subfamily. The Spartaeinae, as denned here, is now comprised of 13 recent and five fossil genera (Table 2). Of the recent genera, four have been revised — Brettus Thorell, Cocalus Koch, Phaeacius Simon and Portia (see Wanless, 19786, 1979, 198 la, 19816), and a paper on Cyrba Simon, is in preparation. Two genera are here formally transferred into the Spartaeinae from other subfamilies; Cyrba from the Plexippinae (sensu Proszyriski, 1976) and Gelotia Thorell from the Magoninae. One genus, Portia, has been relimited and six new genera are proposed. The introduction of so many new genera in a family which is almost certainly overloaded with generic synonyms requires some explanation. Firstly, with the partial exception of Cyrba, all of the taxa thought to belong in this subfamily have been examined. Secondly, the subfamily is distinctive and would have been intuitively recognised by early taxonomists from the presence of relatively large posterior median eyes. Although it is now considered that at least two subfamilies are involved, the species concerned would even under Simon's classical system have been placed systematically close to one another. Exceptions may occur amongst those genera in which the posterior median eyes have been reduced, as for example in Cyrba and some species of Gelotia. Finally an attempt has been made to limit genera on the basis of synapomorphies and then place them in small and hope- fully recognisable monophyletic groups, precisely the strategy advocated by Platnick & Shadab(1979). The standard abbreviations and measurements are those used by Wanless (19780), but for the leg spination the system adopted is that used by Platnick and Shadab (1975). Morphological characters The following account of selected morphological characters provides the basis for the present taxonomic conclusions and clarifies some points which have been misinterpreted in earlier revisions (Wanless, 19780 & b). One new character, the femoral organ, is described and simple abbreviations (M,, M2, M3) used to designate elements of the distal haematodocha and palpal tegulum. Posterior median eyes These eyes are usually classified as being either small/minute or relatively large in relation to the posterior lateral eyes and I cannot recall a single instance in which there has been difficulty in assigning one state or the other. In the majority of salticids the posterior median eyes are small and it has been shown that in some species, Metaphidippus harfordii (Peckham 138 F. R. WANLESS & Peckham) and Phidippus johnsonii (Peckham & Peckham), their retinae are vestigial (Eakin & Brandenburge, 1971). By contrast, in Portia they are large (Wanless, 19786) and the retinal anatomy is non- degenerate as in the other lateral eyes (Blest, 1983; pers. comm.). It is therefore assumed that large posterior median eyes are primitive for Salticidae. As far as I am aware, large posterior median eyes only occur in fossil genera (see Table II) and in recent old world genera of the subfamilies Lyssomaninae and Spartaeinae, and the Cocalodes- group of genera (i.e. Cocalodes Pocock, Allococalodes Wanless, Holcolaetis Simon and Sonoita Peckham & Peckham). They have been reduced at least four times in the Lyssomaninae, Lyssomanes Hentz and Chinoscopus Simon from the new world, Pandisus Simon and Onomastus Simon from the old, and twice in the Spartaeinae i.e. Cyrba and Gelotia. The latter genus including four species with large posterior median eyes and two with small. Homann (1971) has suggested that in spiders the eyes were originally more or less arranged in parallel rows of four equal sized eyes, that specialisation within families occurred through the enlargement of some eyes and their corresponding optic areas of the brain. Ontogeny has shown that in salticids the posterior eye row is primarily procurved and that eyes normally referred to as the posterior medians are in reality the posterior lat- erals. In the same work, Homann treated lyssomanine spiders as a distinct family, the Lyssomanidae, and demonstrated that their secondary eyes (i.e. AL, PM, PL), unlike those of the Salticidae, have all the retinal nuclei distal to the rhabdomes, as in most spiders, and not outside the pigment cups as in the Salticidae. Also, the lateral eyes lack elongated rods. Further studies by Blest (1983, pers. com.) confirm that the secondary eyes of Lyssomanes are different from those of advanced salticids. However, he advises against placing too much taxonomic weight on the importance of eye characters as they are liable to rapid selection. Clearly, the eyes of old world lyssomanines (sensu Wanless, 1980c) should be examined before drawing any phylogenetic conclusions. For the present therefore, I would still main- tain that lyssomanine spiders merit only sub familial rank while at the same time drawing attention to the fact that the monophyly of the group has still to be proven. Cheliceral teeth The structure and number of teeth on the inner margins of the chelicerae have been used to divide the Salticidae into three major divisions, the Unidentati, Fissidentati and Pluridentati (Simon, 1901). The system has been much criticised (Petrunkevitch, 1928; Proszynski, 19710; Wanless, 1975; Kaston, 1981) on the grounds that it is artificial and there are numer- ous examples where the number and structure of the teeth are intraspecifically inconsistent or asymmetrical. It has also been argued, correctly in my view, that the fissidentate tooth i.e. a tooth with two or three points, is essentially transitional between a single tooth (uniden- tate) and two or more separate teeth (pluridentate). Unfortunately, and contrary to the remarks of Lehtinen (1975) and Wanless (19806), the sister group of the Salticidae is far from certain, it is therefore difficult to decide if the presence of numerous teeth on the inner margin represents a primitive or derived condition. Salticids lacking teeth or with a single tooth on the inner margin tend to share more derived characters i.e. small posterior median eyes and relatively simple (?) secondarily reduced male palpal organs, suggesting that the absence of teeth may also be a derived condition. However, even if these assumptions are correct they tell us little of the phylogeny as the trend towards a reduction in the number of teeth has probably occurred on numerous occasions. While there can be no doubt that the divisions are artificial, it is suggested that contrary to current opinion we may yet find that they form useful key characters. For in practice the vast majority of salticids can be easily sorted into one division or another. Exceptions will of course always occur, but once recognised they may be allowed for in the key. Fovea The fovea can sometimes provide a useful key character, but it does not appear to be of much use in assessing relationships as its length and position are variable and seemingly SPIDER SUBFAMILY SPARTAEINAE 139 unrelated to carapace shape. In species of both Lyssomaninae and Spartaeinae the fovea is generally elongate, and positioned further back on the thorax than is usual in many other groups, suggesting that it may represent a primitive condition. The derived state is either its absence or a more forward location — usually more or less between the posterior margins of the posterior lateral eyes. Femoral organ (Figs 30A-F; 32A-D) This unusual structure only occurs on the underside of the femora of the first pair of legs in some males belonging to the genera Brettus, Gelotia, Mintonia gen. n., and Spartaeus. It varies in development and has probably been lost in some species. In Spartaeus spinimanus (Thorell) and Gelotia bimaculata Thorell, the femoral organ is represented by a small angu- lar tubercle bearing a shallow perforated depression surrounded by irregular pleats (Fig. 30A-F). It is clearly visible under the optical microscope, but in species where the tubercle is lacking the organ may be recognised as a pale amber spot or streak. In Mintonia tauricornis sp. n., the femoral organ, appearing as a pale amber spot under low power, is probably non- functional consisting of a ring of pleats with the central perforations lacking (Fig. 3 1 A). Mintonia ramipalpis (Thorell) is similar, but there are scattered pores a few of which are apparently setose (Fig. 31B-D). However, in an untreated specimen, i.e. one which had not been cleaned in an ultrasonic bath previous to coating for SEM, the femoral organ is seen to contain numerous amorphous globules, almost certainly a secretion (Fig. 31E-F). Some globules are still attached to the secretory pores a few of which are evidently plugged (Fig. 3 1 F, arrowed), but in reality the beginning of an exudate; it therefore seems unlikely that 'true' setose pores are present. The phenomenon is in one sense an artifact as the exudate, possibly a sex pheromone, will have been produced and coagulated while the specimen was languishing in spirit. In Brettus cingulatus Thorell, the femoral organ, appearing as a minute pale amber streak and overlooked by Wanless (1979), has the form of a perforated gully which appears to contain an amorphous secretion (Fig. 32A-C). When poorly developed and only evident as a pale amber spot, the femoral organ re- sembles those sometimes found on the first and second pairs of legs of certain female spiders in the family Mysmenidae (Platnick & Shadab, 1978). Unfortunately mysmenids are rare in collections and it has only been possible to examine the legs of a single unidentified Portuguese species. The first sample, a leg I, disintegrated in preparation and was lost; the second, a leg II, shows the femoral organ as a rather featureless spot (Fig. 32D) which bears a passing resemblance to that found in M. tauricornis (Fig. 3 1 A). In some mysmenids, includ- ing the Portuguese species, the femoral organ appears to be more pronounced on the first pair of legs, while some published figures suggest that the organ has the form of a low mound (Kraus, 1967; Brignoli, 1980). Clearly further studies are warranted, but as salticids and mysmenids belong to different phyletic groups it would be surprising if the femoral organs proved to be homologous. For the present, well developed femoral organs are regarded as primitive, the derived con- dition being their vestigial state or absence. On the whole they have been of little use in resolving intergeneric relationships. Retrolateral tibial apophysis (RTA) The retrolateral tibial apophysis shows a degree of development which is evidently unparal- leled within the Araneae. In some genera e.g. Portia, Phaeacius and Yaginumanis gen. n., it is a solid, occasionally ramose prong (Figs 6E; 28A; 29D), while in others it has associated ducts with median or distal openings (Figs 2 ID; 32E, F; 33A-F). In one genus, Cocalus, the RTA is saucer-shaped and supports a membraneous finger-like extension of the tibia (Fig. 22C). Yet other genera (Cyrba, Gelotia and Meleon gen. n.) are characterised by RTAs which arise from a membraneous base, some of which may be moveable (Figs 20C; 26F). In Gelotia syringopalpis sp. n., and Mintonia melinauensis sp. n., the openings of the apophyses can be seen under the optical microscope (Figs 2 ID; 13C), but in other species 140 F. R. WANLESS the openings can only be detected by SEM (Figs 32E, F; 33A-E). Unfortunately it has only been possible to examine a few specimens and experience has shown that it is probably unwise to assume the presence of openings. For example, the RTA of Mintonia ramipalpis (Thorell) has every appearance of possessing a duct, but this was not confirmed by SEM studies (Figs 14H; 34 A, B). Also, the occurrence of a membraneous base to the RTA is not necessarily indicative of openings— compare G. bimaculata Thorell which has an opening (Fig. 3 3 A, B) with Meleon kenti (Lessert) and Cyrba algerina (Lucas) in which they are lacking (Fig. 34C, D, F). The purpose of these complex apophyses is unknown. They could be functionally homolo- gous with the femoral apophyses of Asemonea O.P.-Cambridge and Pandisus Simon (see Wanless, 1980c) and produce a contact pheromone or secretion for plugging the female copu- latory openings. In G. bimaculata there is a sclerotised fold opposite the posterior margin of the epigyne (Fig. 17C, arrowed) suggesting that this region may receive the tip of the RTA. However, there is no evidence to indicate that this may occur in other species or genera. The apophysal openings may have been lost in some species of Mintonia and it is possible that ducted apophyses are a primitive, rather than an advanced character in salticids. Distal haematodocha Wanless (19786) referred to the distal haematodocha of Portia as a tripartite membraneous apophysis. This was incorrect since fresh material has shown that although the three ele- ments are contiguous only two, for convenience labelled M, and M2, can properly be de- scribed as being part of the distal haematodocha. The third element discussed below and labelled M3 is thought to represent a separate distal modification of the tegulum. In ventral aspect M, lies partially over the embolic base and is usually on the prolateral side of the embolic duct where it enters the embolus. It often develops a minute lobe (Fig. 16A-C), but in Neobrettus and Cyrba they are large and petal-like (Figs 24D; 25F), while in Phaeacius there is a long filamentous process, erroneously labelled as a secondary conduc- tor in Wanless (198 la). M2 lies on the retrolateral side of the embolus and is often seen as a small lobe or membraneous patch lying alongside or slightly apart from the embolus (Fig. 1 6 A-C). Only occasionally does it extend posteriorly to produce a translucent ledge, Brettus, or fuse with M3, Gelotia. In ventral aspect M3 lies above M2 and usually extends transversely or obliquely across the tegulum forming a narrow, delicate translucent ledge in Portia and Meleon, a lobe in many species of Mintonia and a short filament in Spartaeus. In Gelotia it takes the form of a curtain-like membrane not readily separated from M2. Although the distal haematodocha and tegular ledge are sometimes characteristic of spartaeine genera, the development of the former in other salticids is uncertain as it is not always evident in unexpanded palps, possibly being overlooked, whereas the tegular ledge seems to have no parallel in other salticids. The complexity of the distal haematodocha and presence of a tegular ledge may in themselves be synapomorphic for Spartaeinae. Tegular furrow This structure which forms an integral part of the tegulum varies considerably. It is some- times obscured by the embolus, distal haematodocha and the tegulum itself, especially when bulbous. It is usually situated on the retrolateral side of the tegulum and may be recognised as a pit, which is sometimes dark and may extend posteriorly as a groove alongside the retro- lateral margin. Below the cuticle of the tegulum, adjacent to the pit or near the base of (M3) there is sometimes a black disc-like structure (Fig. 19F). The pit may be shallow and open with a thick anterior wall and slight hood (Fig. 24D), deep and almost circular (Fig. 35C), irregular or crescent-shaped (Fig. 9C). The groove may be deep (Fig. 36E), lacking or short and shallow (Figs 12E; 35E), occasionally terminating in a series of fine striae (Fig. 22D). In at least two species, Phaeacius lancearius (Thorell) (see Wanless, 198 la) and Brettus cingulatus Thorell, there is a minute pore in the wall of the pit which is evidently lacking in other genera. SPIDER SUBFAMILY SP ART AEINAE 141 The furrow is not known to occur in other Salticidae and its presence is regarded as a synapomorphy linking all members of this subfamily. Its function is unknown. Ventral tibial apophysis The ventral tibial apophysis often has a characteristic oblique profile (Figs 7G; 19F; 22D) when viewed in ventral aspect. It varies in development and is usually obscured by tibial setae in the intact unshaven palp. It was initially considered to represent a second synapo- morphy supporting this subfamily, but the occurrence of a similar apophysis in certain amber salticids (p. 146, Fig. 2 A) believed to share closer affinities with the Cocalodes-group of genera raises doubts as to the validity of the proposal. Cymbium The basal region of the cymbium is often modified. In some genera e.g. Portia, Cyrba and Gelotia there are evidently non-functional protuberances and excavations, while in others there are dorsal protuberances and recesses that interlock with tubercles on the palpal tibiae, which would appear to limit the extent to which the cymbial/tibial joint can be articulated. A similar protuberance on the palpal patella limits the flexing movement of the tibia. Pro- visional observations suggest that in Cyrba and Meleon the development of the locking mechanism is variable. In Mintonia, Phaeacius, Spartaeus Taraxella, Veissella and Yaginumana it is lacking or poorly developed, while in Brettus, Gelotia, Neobrettus and Portia it is relatively strong. Also, in Brettus and Neobrettus there is a basal retrolateral exca- vation which is apparently used, at least in part, to protect the tip of the long filamentous embolus (Figs 23F; 24C). The floor of the excavation is membraneous and seems to be con- tiguous with the segmental membrane uniting the cymbium and tibiae. A similar, rather sub- triangular region is found in some species of Meleon (arrowed Fig. 26B). Its purpose is unknown, but in Meleon, at least the membraneous area plays no part in retaining the embolus. Although some cymbial modifications are unique to the genera concerned, the locking mechanism is probably a primitive feature of these palps, and in any event, as a character it has not been of much use in determining affinities. Median apophysis This male palpal structure, which does not occur in members of this subfamily, is only found in Lyssomaninae, the Cocalodes-group of genera (see p. 138) and the amber genus Eolinus. Within these groups it is sometimes seen as a (?) moveable bifid prong which arises from a membraneous or pleated region of the tegulum (Fig. 1A; see also Wanless, 1982). Its occurrence in Eolinus and the implications thereof are discussed below. Subfamily SP ART AEINAE nom. n. Boetheae Simon. 1901: 388. 400. Boethinae Petrunkevitch, 1928: 57, 181; 1939: 184. Bonnet, 1955: 892. Roewer, 1957: 933. REMARKS. In spite of Bonnet's remarks (Bonnet, 1955), Strand (1929) was correct to regard Boethus Thorell, 1878 as a junior homonym of Boethus Foerster, 1868. However, his replacement name (Boethuold) cannot be justified as Spartaeus Simon, a junior synonym of Boethus, is available. Since the subfamily name Boethinae is therefore invalid it is pro- posed that Spartaeus becomes the nominate genus of the subfamily Spartaeinae. In reality only the nomenclature has changed as the type species of Spartaeus (S. gracilis Thorell) is a junior subjective synonym of Boethus spinimanus Thorell, the type species of Boethus. DEFINITION. A heterogeneous group of spiders ranging from about 3-0 to 11-0 mm in length. Markings occasionally conspicuous; general habitus sometimes hirsute with tufts and fringes. Carapace: of various shapes, usually elevated with highest point at about level of posterior 142 F. R. WANLESS lateral eyes, rarely near centre of thoracic part; fovea usually long, sulciform and situated more or less just behind posterior lateral eyes. Eyes: in three rows, those of the second often fairly large. Clypeus: low to high with three long setae in lower space between anterior median eyes. Chelicerae: moderately robust, usually stronger in female; vertical or slightly inclined anteriorly, more or less parallel or slightly diverging; apophyses or spurs lacking; promargin with three to seven teeth, retromargin with three to nine, variously described as teeth or denticles. Maxillae: moderately long to long with outer distal margins varying from rounded to oblique; modifications lacking. Labium: about as long as broad or longer than broad. Sternum: more or less elongate scutiform. Abdomen: usually elongate ovoid with four indistinct apodemal spots; markings variable; spinnerets moderately long; anal tubercle cone-like; position of colulus usually indicated by scanty tuft of setae between tracheal spiracle and base of anterior spinnerets; tracheal spiracle an obscure transverse slit near base of anterior spinnerets. Legs: usually long and slender with numerous spines; sometimes strongly fringed; claws usually pectinate; tufts present; scopulae absent, but minute iridescent setae often present on tarsi and metatarsi; some males with femoral organs on first pair of legs (Figs 30A-F; 31A-F). Female palps: generally moderately long and slender with apical claw. Male palps: generally complex, sometimes with interlocking tubercles between cymbium/tibia and tibia/patella; tibiae with somewhat oblique ventral apophyses, rarely reduced, and usually complex retrolateral, rarely dorsal, apophyses sometimes possessing membraneous elements, distal openings or adjacent tube-like process; cymbium with distal scopula, often with basal protuberances or excavations; embolus usually slender, of various lengths, arising apically or from prolateral side of tegulum, pars pendula or basal sheath rarely evident; distal haematodocha usually bearing delicate transparent or translucent lobes, flanges or filaments (elements M, and M2); tegulum of various forms, with a furrow (Figs 35A-E; 36E) and usually with a delicate apical ledge or lobe (element M3). Epigynes: of vari- ous forms; copulatory openings sometimes separated by median guide or septum, often plugged or obscure; introductory ducts variable in length, sometimes lacking; spermathecae often globular, large and dark with fertilisation ducts on posterior margin. DIAGNOSIS. Male salticids belonging in the subfamily Spartaeinae may be recognised by the presence of a palpal tegular furrow (see p. 140). Females are more difficult and may not always be distinguished in the absence of males, species with small posterior median eyes presenting the most problems, fortunately only two genera Gelotia and Cyrba are involved. Gelotia would not in all probability be recognised in the presence of a mixed group of female salticids, whereas Cyrba can even under these circumstances be assigned to Spartaeinae by the unusually long fovea and presence of numerous teeth on the posterior margin of the chelicerae. Females with large posterior median eyes are slightly less difficult for in practice they can only belong in one of three groups — the Lyssomaninae, Spartaeinae or Cocalodes- group. The absence of a lyssomaniform type of carapace and eye pattern (see Wanless, 1980) quickly eliminates lyssomanine genera. But to distinguish between the Cocalodes- group and Spartaeinae it is necessary to consult the literature for descriptions and figures of the epigynes. Geographic distribution patterns are of some help as the genera of the Cocalodes- group are less widespread — Cocalodes and Allococalodes Wanless are only known to occur in the Moluccas and New Guinea, Holcolaetis, a genus of large flattened spiders is African, whereas Sonoita, represented by a single species, is only known from Cape Province, South Africa. A more practicable diagnosis will be presented when all of the Cocalodes-group have been revised. AFFINITIES. The integrity of Spartaeinae is primarily based on the presence of the palpal tegular furrow, but until its degree of development (if any) in other salticids is at least partly understood there is little prospect of determining subfamial relationships which for the pres- ence remain obscure. I am unable to suggest derived characters supporting a sister group relationship with lyssomanine spiders, which as mentioned above may not be monophyletic. Part of the problem stems from the probability that structural elements of the male palpal SPIDER SUBFAMILY SP ART AEINAE 143 organs of lyssomanines have been misinterpreted by myself and other authors, for instance, the element labelled tegulum in Wanless (1980c) is almost certainly a modified conductor. The Cocalodes-group of genera probably represents another subfamily which seems to be characterised by the form of the median apophysis. The amber salticid discussed below (palp. Figs 1A, B; 2A-C) although closer to the Cocalodes-group by virtue of its median apophysis, is similar to Spartaeinae in the form of its tibial apophyses suggesting a possible link between the two groups. Alternatively, some old world lyssomanines possess a pale spot on the tegulum (Asemoned) or scale-like protuberance (Pandisus) that could represent either a vestigial or germinal median apophysis, thus supporting a Coca/odes- group/lyssomanine dichotomy. Broadly speaking, Lyssomaninae, Spartaeinae and the Cocalodes- group of genera probably belong to the most plesiomorphic branches of the family; they seem to be related, but the incongruencies cannot be resolved. The question of intergeneric relations is also difficult as the majority of subfamilies are artificial and polarity assessments based on outgroup comparison with other salticids are largely intuitive. The subject of relationships should perhaps have been put aside until a broader spectrum of salticids has been revised, but in view of recent studies on the optics and behaviour of Portia, a brief review of generic affinities is justified, if only to highlight the problems and provide a basis for future criticism. Spartaeus. The strong ventral spines on legs I and to a lesser extent on legs II appear to be synapomorphic for the genus. But as there are only two known species, only one of which is known from both sexes, I have been unable to detect other derived characters. Its affinities are uncertain. Yaginumanis. This monotypic genus is difficult to place. It lacks the characters defining other genera and the pleated region of the tegulum M3 appears to represent its only autapo- morphy. The robust retrolateral tibial apophyses of the male palps resemble those of Portia and to a lesser extent Phaeacius. However I am not sure that we are dealing with a shared synapomorphy as the ancestral state of these heavy apophyses can only be guessed at. The bulbous tegulum, presence of three pairs of ventral spines on metatarsi I, abdominal pattern and reddish black copulatory openings of the epigyne indicate that its affinities could lie near Spartaeus. Taraxella. The broad encircling carapace band and massive tegular apophyses (V and 'y') are autapomorphic for this monotypic genus. Its affinities are uncertain, but if apophysis 'x' is homologous with the regular element M3 then its nearest relative could be Mintonia. Mintonia — Gelotia — Cocalus. These genera present difficulties which I am unable to resolve. Each is supported by synapomorphic male characters viz. Mintonia by the form of the tegu- lar ledge M3 (e.g. Figs 8H; 9C); Gelotia by the cap-like retrolateral tibial apophyses (Fig. 201) and Cocalus by the finger-like protuberance resting in the dish-like retrolateral tibial apophysis (Fig. 22C). Mintonia and Gelotia seem to be close as both genera include males whose retrolateral tibial apophyses bear openings. Similar openings are unlikely to occur in Cocalus, but unfor- tunately this does not necessarily support a Mintonia/Gelotia sister group as the development of this character is uncertain, it is certainly lacking in M. ramipalpis and may not be present in all species of Gelotia. On the other hand the general conformation of the palps of Gelotia and Cocalus is similar, the apical inward curving embolus arising from a lobe-like part of the tegulum in both genera. Furthermore, if the finger-like process of Cocalus is analogous with the amorphous process of Gelotia (Fig. 20C) then there are possibly stronger reasons for suggesting that Gelotia and Cocalus are closer than either is to Mintonia. Meleon — Veissella. The hyaline socket of the palpal tibial apophyses is synapomorphic for Meleon, while the thin flange-like palpal tibial apophyses and opposing apophyses of the patellae and femora (Fig. 27B, D) are autapomorphic for Veissella. They cannot be grouped on the basis of reliable synapomorphies, but their geographical distribution and the general 144 F. R. WANLESS conformation of the male palps, especially the development of the transverse tegular ledge M3 (Figs 26G, E; 27G) suggests, that, in spite of their markedly different tibial apophyses, they are closer to one another than to other genera in the subfamily. Their habitus is also similar but probably symplesiomorphic as high carapaces and leg fringes are also characteristic of Portia and Brettus. Brettus — Neobrettus — Cyrba. The tubular process lying near or alongside the male palpal retrolatral tibial apophysis (Fig. 33C-E) is synapomorphic for Brettus and the slightly bowed legs autapomorphic for Neobrettus. Cyrba, however, is not supported by characters which can at present be described as synapomorphic (see remarks p. 185). The conformation of the male palps, particularly the long slender embolus and open tegu- lar furrow, indicates that the spiders of this heterogenous group are closely allied. Relation- ships within the group are however uncertain as the alternatives seem to be balanced by an equal number of supposed synapomorphies. The petal-like element of the distal haemato- docha M, and presence of an embolic guide, a groove on the outside wall of the tegular furrow, supports a Cyrba/Neobrettus relationship. On the other hand, Neobrettus shares with Brettus a subtrapezoid tegulum and basal cymbial modifications which appear to protect the embolic tip. Furthermore, in Neobrettus there is a curious minute delicate apophysis (Fig. 24D) which could be a degenerate auxilliary process similar to that of Brettus. If this is correct then the case for a Brettus/Neobrettus dichotomy is marginally stronger than that between Cyrba and Neobrettus. The subapical prolateral origin of the embolus and to a lesser degree the distally sinuous element of the seminal ducts suggests that these genera share affinities with Portia and Phaeacius and that together they may form a natural group within the subfamily. Phaeacius — Portia. Whereas Phaeacius possesses several uniquely derived characters (pro- nounced pars pendula, massive retrolateral tibial apophyses and a long filamentous process Mj), Portia is, in spite of its distinctive appearance, more difficult to characterise on the same basis. The lateral projecting embolus (Fig. 29A, D) and the large dorsal angular flange on the cymbium being the only synapomorphies which I can suggest at the present time. The well developed tufts and fan-like fringes characteristic of all Portia species are probably symplesiomorphic for as mentioned above elements of this ornamentation appear to a lesser extent in other genera. Their affinities are uncertain for, apart from general similarities in the conformation of the palpal organs, the only derived character which seems to link Phaeacius and Portia is the large size of the palps. A feature which alone offers only minimal support for the supposed relationship. Fossil genera Some of the amber salticids described by Petrunkevitch (1924) are preserved in a mixture of clarite and mineral oil on microscope slides in the collections of the British Museum (Natural History). They are neat and well documented, but an examination of this material has shown that important genitalic characters are largely obscured and not a single species could be reliably placed in the Spartaeinae as defined here. However, the condition of one slide labelled Eolinus succineus Petrunkevitch, no. 3782, offered a partial solution to the problem as a fracture line through the amber block indicated that it might be possible to expose the palps which were totally obscured by a crushed carapace. The specimen, orig- inally described as badly damaged (Petrunkevitch, 1942; 424) was easily removed from its clarite mount and cleaned in xylene; pressure from a fine scalpel being sufficient to fracture the block which broke into several pieces revealing a dark, but nevertheless well preserved palp (Fig. 1A-B). This clearly shows that the specimen is not conspecific with E. succineus (Fig. 2D) and neither does it entirely agree with published figures of E. theryi Petrunkevitch, or E. tystschenkoi Proszynski & Zabka. It may represent a new taxon, but of more import- ance is the fact that the palp appears to possess a median apophysis which looks similar SPIDER SUBFAMILY SPARTAEINAE 145 ma B Fig. 1 (A-B) Palp in amber labelled Eolinus succineus Petrunkevitch, no. 3782: A, ventral view, note lighter region at base of median apophysis; B, tibia showing ventral and retrolateral apophyses. Abbreviation: ma, median apophysis. 146 F. R. WANLESS B Fig. 2 (A-C) Palp in amber labelled Eolinus succineus Petrunkevitch, no. 3782: A, ventral view; B, tibia, dorsal; C, tibiae, retrolateral. D, palp in amber also labelled Eolinus succineus Petrunkevitch — slide no. 29 126- A, androtype. Note distinct forms of retrolateral tibial apophyses. Abbreviations: rta, retrolateral tibial apophysis, va, ventral apophysis. to and may be homologous with the median apophysis found in Cocalodes (see Wanless, 1982). The paler region around the base of the apophysis (Fig. 1A) could be an artifact of preservation in amber, but it is believed to represent the remains of the basal pleating, chacteristic of some median apophyses. There is no evidence of a tegular furrow which could admittedly be overlooked as the palp is dark. Other interesting features are the dorsal and retrolateral apophyses (Figs 1 B; 2 A-C), the latter resembling that of Gelotia in general form. In addition there is a small ventral apophysis (Fig. 1 B) not unlike that found in species of Spartaeinae. In spite of these similarities the absence of a tegular furrow excludes this taxon from this subfamily, its affinities together with those of E. theryi and E. tystschenkoi probably lie closer to the Cocalodes-group. The relationships of other fossil genera (see Table 2) placed in this subfamily (Petrunkevitch, 1958) have been discussed by Proszynski (1980) and for the present no for- mal changes are proposed. However, as most recent genera believed to show affinities with amber salticids will have been revised in the fairly near future, a decision should be made as to whether we can justify removing the palps of type specimens from their amber blocks. Modern techniques, considerably less crude than that described above, will minimise the risk of damage but it is clear that unless male palps are examined properly amber specimens will be of limited taxonomic value. Key to genera of the subfamily Spartaeinae Females of Taraxella are unknown. 1 Habitus as in Fig. 24 A; highest point of carapace clearly near centre of thoracic part (Fig. 24B) (Bhutan; West Malaysia) NEOBRETTUS %en. n.(p. 181) Habitus otherwise; highest point of carapace at about level of posterior median eyes ... 2 2 Male palps with massive apophyses 'x' and 'y' (Fig. 7G) (Sarawak) . . . TARAXELLA gen. n. (p. 155) Male palps lacking apophyses 'x' and 'y' 3 3 Carapace with low elevation in eye region (Fig. 22A, B); male RTA with sinuous finger-like protuberance (Fig. 22C) (Australia; Indonesia) COCALUS Koch (p. 1 80) - Carapace lacking low elevation in eye region; palpal RTA otherwise 4 4 Male palpal patellae and femora with opposing retrolateral apophyses (Fig. 27B, D); epigyne with median guide as in Fig. 27E; (South Africa) VEISSELLA gen. n. (p. 1 89) - Male palpal patellae and femora lacking retrolateral apophyses (see note 1); epigynal guide other- wise or lacking 5 SPIDER SUBFAMILY SPARTAEINAE 147 5 Male palpal tibiae with flask-like vacuole giving rise to tubular process adjacent to or separate from RTA (Fig. 2 3D, F); Epigynes with long median introductory ducts; carapace with broad marginal bands of silky white hairs (see note 2) (Burma; India; Madagascar; Sulawesi; Sri Lanka) BRETTUSThoTQ\\(p. 181) Male palpal tibiae lacking flask-like vacuole and tubular process; epigyne otherwise; carapace bands if present more irregular (c.f. Portia) and comprised of coarser setae 6 6 Male palp with massive RTA (Fig. 28C); distal haematodocha with long filamentous process (Fig. 28A); underside of female coxae IV clothed in minute spatulate setae (Nepal; India; Burma; Singapore; Sumatra; Java; Philippines) PHAEACWS Simon (p. 190) Male palp and coxae otherwise 7 7 Male palpal RTA cap-like in ventral aspect (Figs 17D: 18D; 19F; 201), sometimes possessing a backward pointing syringe-like apophysis (Fig. 211); epigynes with thin median ridge (Figs 16F; 17C), or if lacking then apparently with two pairs of rounded spermathecae (Fig. 2 1C) (see note 3) (Indonesia; Malaysia) GELOT1A Thorell (p. 169) Male palpal RTA and female epigyne otherwise 8 8 Posterior median eyes small (PM : PL about 1 : 4) (Ethiopian, Mediterranean and Oriental Regions) CYRBA Simon (p. 185) Posterior median eyes relatively large (PM : PL about 3:4) 9 9 Legs I with stiff fan-like fringes or if lacking (one Madagascan species) then palpal cymbium with deep basal excavation (see note 4) 10 - Legs I without fan-like fringes 11 1 0 Very hirsute, abdomen with tufts; anterior eye row weakly to strongly procurved in frontal view; palpal cymbium with pronounced dorsobasal flange (Fig. 29C, E) (Australasian, Oriental and Ethiopian Regions) PORTIA Karsch(p. 191) Moderately hirsute, abdomen clothed in minute, often iridescent setae; anterior eye row weakly to strongly recurved in frontal view; palpal tibiae with apophyses arising from membraneous socket (Fig. 26F) (Africa; Madagascar) MELEON %m. n.(p. 186) 1 1 Tibiae of legs I with numerous long ventral spines (Fig. 5C); chelicerae with 5 or 6 promarginal teeth SPARTAEUS Thorell (p. 147) Tibiae of legs I with ventral, lateral and usually dorsal spines (see note 5); chelicerae with 3 teeth on prolateral margin 12 12 Male palp with stout RTA, bulbous tegulum and pleated tegular ledge (M3) (Fig. 6E, J); female epigyne with median blackish red copulatory openings (Fig. 61) (Japan) . . . YAGINUMANIS gen. n(p. 152) - Male palps with RTA's slender (Figs 8F, 1 IB, 13B), ramose (Fig. 14B) or bifid (Figs 9C; 12D); tegular element (M3) a delicate transparent ledge (Fig. 8H) or lobe (Fig. 9C), rarely sclerotised (Fig. 14B); epigynes with rounded spermathecae (Figs 8D; 10F; 12B; 15A) and more or less central copulatory openings (Indonesia; Malaysia) MINTONIA gen. n. (p. 157) Notes on the keys 1. The male palpal femora ofGelotia argenteolimbata (Simon) possesses a large ventral apophysis (Fig. 18C), which may initially be confused with that of Veissella durbanii (Peckham & Peckham). 2. It is not certain if silky white carapace bands are present in Brettus celebensis (Merian) and B. madagascarensis (Peckham & Peckham) which are known only from type specimens. However they are characteristic of Indian and Sri Lankan species and their presence may help to place females in the correct genus. 3. The epigyne of Mintonia syringopalpis sp. n., appears at first sight to possess two pairs of sperma- thecae, but in reality the anterior pair are looped parts of of the introductory ducts. 4. Meleon madagascarensis (Wanless) is the only species of the genus without leg fringes. The palp is however quite distinctive and unlikely to be confused with any other (see Wanless, 1978). 5. Females of Yaginumanis sexdentatus (Yaginuma) have a single median prolateral spine on tibiae I which could easily be overlooked. Genus SPARTAEUS Thorell Boethus Thorell, 1878: 220. Type species Boethus spinimanus Thorell, by original designation and monotypy [junior homonym of Beothus Foerster, 1868]. Scudder, 1882, 1: 46; 2: 40. Peckham & Peckham, 1885: 268, 295. Simon, 1901: 400, 401, 402. Petrunkevitch, 1928: 181. Neave, 1939, I: 444. Roewer, 1954: 933. Bonnet, 1955: 892. Wanless, 1978: 85. 148 F. R. WANLESS Spartaeus Thorell, 1891: 137. Type species Spartaeus gracilis Thorell, by original designation and monotypy. Simon, 1901: 401, 402 [= Boethus]. Waterhouse, 1902: 347. Petrunkevitch, 1928: 246. Neave, 1940, IV: 230. Nealces Simon, 1900: 30. Type species Nealces striatipes Simon, by original designation. Simon, 1901 : 400, 403 [= Boethus]. Waterhouse, 1902: 236. Petrunkevitch, 1928: 234. Neave, 1940, III: 273. Boethuola Strand, 1929: 15 [replacement name for Boethus Thorell]. Bonnet, 1955: 892. DEFINITION. Medium to large spiders ranging from about 4-0 to 8-5 mm in length. Sexual dimorphism not marked, patterns (Figs 4A; 5A) fairly well defined, first pair of legs with numerous long ventral spines on tibiae. Carapace (Figs 3D; 4B; 5B): moderately high, longer than broad, widest at level between coxae II and III: fovea long and sulciform, apex just behind or level with posterior margins of posterior lateral eyes. Eyes: with moderately large lenses set on pronounced tubercles; anteriors subcontiguous with apices slightly recurved in frontal view and recurved in dorsal; anterior medians largest; anterior laterals greater than half diameter of anterior medians; pos- terior medians relatively large, positioned closer to and inside optical axis of anterior laterals; posterior laterals as large as anterior laterals and set well inside lateral margins of carapace when viewed from above; posterior ocular quadrangle broader than long and wider behind; entire quadrangle occupying about 52 per cent of carapace length. Clypeus: moderately low. Chelicerae: moderately robust with lateral condyles sometimes strong; inclined anteriorly; parallel or slightly diverging; fang moderately long and curved; promargin with five or six teeth, retromargin with seven to eleven denticles. Maxillae: moderately long, slightly diverg- ing with rounded outer distal margins. Labium: about as long as broad, half or slightly less than half maxillae length. Sternum (Fig. 4D): elongate scutiform. Abdomen: elongate ovoid; spinnerets moderately long; posteriors slender and longer than robust anteriors, medians slender and slightly shorter than anteriors. Legs: long and slender; first pair with numerous long ventral spines on metatarsi and tibiae, other leg spines weaker; males with femoral organs, a minute tubercle on underside of femora I (Figs 3E; 30A-D); claws pectinate; tufts present; scopulae lacking, but legs I with minute setae (c.f. Portia) covering venter of tarsi and forming two rows on metatarsi. Female palps: moderately robust with apical claw. Male palps: moderately complex with poorly developed interlocking protuberances; patellae with rudimentary anterodorsal tubercle; tibiae with dorso-prolateral tubercle, a slight dorso- retrolateral flange, ventral and retrolateral apophyses, the latter broad with ventral spike; cymbium extended and narrowing distally with apical scopulae and slight retrolateral lobe; embolus moderately long, slender and curved; distal haematodocha forming a membraneous patch M, and a translucent prong M2 containing a sclerotised rod-like structure; tegulum bulbous with peripheral seminal ducts, a short filamentous process M3 and a crescent- shaped furrow almost completely obscured by the tegulum (Fig. 3A, B); median haematodocha a short broad membraneous tube visible only in expanded palp; subtegulum a pleated and partly sclerotised disc at distal end of basal haematodocha. Epigyne: variable, refer to species descriptions. DIAGNOSIS. From other genera in the subfamily by details of the secondary genitalia and presence of numerous ventral spines on the tibiae of legs I (Figs 3E; 5C). The two known species are easily separated from one another and a key is hardly necessary. Spartaeus spin! man us (Thorell) (Figs 3A-F; 4A-G; 30A-D; 33F; 35A) Boethus spinimanus Thorell, 1878: 221, 309, juvenile. Holotype juvenile Amboina, (MCSN, Geneva) [examined]. Thorell, 1881: 431, 705. Simon, 1901: 401, 402. Petrunkevitch, 1928: 181. Roewer, 1954:933. Bonnet, 1955:893. Spartaeus gracilis Thorell, 1891: 6, 137, <5. Holotype d, Sumatra, (UZM, K0benhavn) [examined]. Roewer, 1954: 933. Sparthaeus gracilis: Bonnet, 1955: 893 [lapsus calami]. Boethus gracilis (Thorell): Simon, 1901: 402. Reimoser, 1925: 90. Roewer, 1954: 933. Bonnet, 1955: 893. Proszyriski, 1971: 385. Syn. n. SPIDER SUBFAMILY SPARTAEINAE 149 Nealces striatipes Simon, 1900: 30, rf. LECTOTYPE cT (here designated) Java, (MNHN, Paris) [examined]. Roewer, 1954: 933. Bonnet, 1955: 893. Boethus striatipes (Simon): Simon, 1901: 401, 402. Roewer, 1954: 933. Bonnet, 1955: 893. Proszynski, 1971:385. Syn. n. Nealces caligatus Simon, 1900: 30, 9. LECTOTYPE 9 (here designated) Sri Lanka, (MNHN, Paris) [examined]. Roewer, 1954: 933. Bonnet, 1955: 893. Boethus caligatus (Simon): Simon, 1901: 401, 402. Roewer, 1954: 933. Bonnet, 1955: 893. Proszynski, 1971:385. Syn. n. REMARKS. The general habitus and distinctive spination of legs I suggests that the juvenile type specimen of Boethus spinimanus is conspecific with and a senior synonym ofSpartaeus gracilis. However, in the case of juveniles there is always an element of uncertainty which cannot be overcome until the species and its geographical distribution are well known. Of the other taxa listed in the above synonymy there is no doubt that they are conspecific as the habitus and distinctive secondary genitalic organs are alike. DIAGNOSIS. S. spinimanus is easily distinguished from S. thailandica sp. n. by the presence of median epigynal guides in females (Fig. 4E). Males of thailandica are unknown. Male from Sarawak, in fair condition. Carapace (Fig. 3D): light brown with blackish mottling on sides and a central tapering yellow-brown band on thoracic part; clothed in recumbent Fig. 3 Spartaeus spinimanus (Thorell), rf: A, palp, ventral; B, distal half of tegulum; C, palp, retrolateral; D, carapace, lateral; E, leg I; F, retrolateral tibial apophysis. 150 F. R. WANLESS brown and whitish hairs, shiny under some angles of illumination. Eyes: with black sur- rounds; fringed by whitish hairs. Clypeus: thinly clothed in light brown and whitish hairs. Chelicerae: yellow-brown with sooty markings and scattered fine brown hairs; promargin with five teeth, retromargin with seven denticles. Maxillae and labium: pale yellow-brown. Sternum: pale yellow-brown with darker margins; shiny with scanty clusters of short stiff light brown hairs opposite coxae. Coxae: pale yellow-brown, shiny. Abdomen: yellow-brown with blackish lateral mottling; dorsum and sides covered in fine recumbent pale brown/ iridescent lanceolate hairs with testaceous ones on venter; anal tubercle and spinnerets pale yellow, the latter with sooty lateral stripes on anterior and posterior pairs. Legs: long and slender with numerous spines (strongest on legs I) and femoral organ, a small tubercle on underside of femoral I (Figs 3E; 30A-D); legs I with tarsi pale yellow, metatarsi, tibiae and patellae yellow-brown tinged black on lateral sides, femora pale yellow with black lateral stripes; other legs similar, but with longitudinal bands of short pale amber hairs particularly on femora, and vague sooty annuli on metatarsi III and IV. Spination of legs I: metatarsi v 2-2-2; tibiae 3-4-3; femora p 0-1-0, d 1-1-2, r 0-1-0. Palp (Figs 3A-C; 33F; 35A). Dimensions (mm): total length 4-7; carapace length 2-08, breadth 1-72, height 1-28; abdo- men length 2-56; eyes, anterior row 1-54, middle row 1-12, posterior row 1-39; quadrangle Fig. 4 Spartaeus spinimanus (Thorell), 9: A, dorsal; B, carapace, lateral; C, cheliceral teeth, inner view; D, mouthparts, sternum and coxae; E, epigyne; F, vulva, outer view; G, vulva, inner view. SPIDER SUBFAMILY SP ART AEINAE 151 length 1-2 (57 per cent of carapace length). Ratios: AM : AL : PM : PL :: 12-5: 7-5 : 4-5 : 7; AL-PM-PL :: 6-5 : 8; AM : CL :: 12-5 : 3. Female from Java (in same vial as lectotype d1 of Nealces striatipes), in fair condition. Similar to d1 except for the following: colour markings more clearly denned, possibly an artifact of preservation. Chelicerae (Fig. 4C): more robust than in d1; orange-brown with sooty mark- ings; sparsely clothed in brownish hairs; promargin with five teeth, retromargin with nine denticles. Abdomen (Fig. 4A): pale yellow clothed in creamy white hairs with vague sooty markings above and blackish mottling covered in dark amber hairs on sides; below, an indis- tinct band of short pale amber hairs from epigyne to spinnerets. Legs: legs and especially spines of legs I more robust than in rf; legs I pale yellow with sooty metatarsi, other legs similar, but metatarsi with vague annuli. Palps: yellow-brown with tarsi orange-brown tinged black distally; clothed in pale yellowish, and light amber hairs. Epigyne (Figs 4E-G): dark reddish brown, relatively large. Dimensions (mm): total length 5-44; carapace length 2-42, breadth 2-04; height 1-4; abdo- men length 3-12; eyes, anterior row 1-8, middle row 1-38, posterior row 1-68; quadrangle length 1-28 (52 per cent of carapace length). Ratios: AM : AL : PM : PL :: 15 : 9 : 5 : 8-5; AL-PM-PL :: 7-10; AM : CL :: 1 5 : 3. VARIATION, d total length varies from 4-2 to 5-8 mm, carapace length 2-0-2-5 mm (five speci- mens). 9 total length 5-4-6-3 mm, carapace length 2-38-2-5 mm (five specimens). One male, the type of TV. striatipes, has a dark orange carapace with the thoracic band poorly defined, also the distal extension of the cymbium is slightly more elongate and narrow. In some males the seminal duct is more clearly defined in the region of the embolic base. DISTRIBUTION. Indonesia: Amboina, Java and Sumatra; Malaysia: Sarawak; Singapore; Sri Lanka. MATERIAL EXAMINED. Amboina: holotype [of Boethus spinimanus], a juvenile, (MCSN, Geneva). Java: Palabuan, lectotype cf [of Nealces striatipes], 299 not types, Fruhstorfer (MNHN, Paris, 20328). Sumatra: Padang, holotype rf, [of Spartaeus gracilis], P. A. Klein, (UZM, K0benhavn); Padang, 19, ix.1913, E. Jacobson, (RNH, Leiden. 540). Sarawak: Marudi, on outside wall of house, Id1, 26.iv.1978, F. R. Wanless, R.G.S./Sarawak Govern- ment Mulu Expedition, (BMNH). Singapore: Icf, H. N. Ridley, (BMNH). Malaya: IcT, 19, no other data, (BMNH). Sri Lanka: Galle, lectotype 9, [of Nealces caligatus], with one juven- ile specimen, E. Simon, (MNHN, Paris, 20537). Spartaeus thailandica sp. n. (Fig. 5A-D) DIAGNOSIS. Distinguished from S. spinimanus by the absence of pronounced median epigynal guides (Fig. 5D). Male. Unknown. Female holotype, in poor condition. Carapace (Fig. 5 A, B): dark mahogany with light yellow- brown thoracic markings and more or less contiguous lateral blotches; thinly clothed in re- cumbent fine whitish hairs. Eyes: with blackish surrounds except anterior medians; fringed by whitish hairs. Clypeus: with scattered light brown hairs. Chelicerae: dark mahogany, shiny with scattered dark brown hairs; promargin with six teeth, retromargin with 1 1 . Maxillae: amber with inner distal margins yellow-brown. Labium: brown-black grading to amber dis- tally. Sternum: yellow-brown with dark amber margins; clothed in pale yellow-brown hairs. Coxae: yellow-brown. Abdomen: dirty pale yellow-brown with blackish markings, ventrally a broad sooty band from epigyne to spinnerets; mostly rubbed, but areas clothed in fine whitish hairs with scattered flecks of pale amber ones. Legs: long and slender; legs I (Fig. 5C), pale yellow-brown with metatarsi and tibiae dark amber and ventrally strongly spinose; legs II similar but metatarsi and tibiae paler with fewer and weaker ventral spines; other 152 F. R. WANLESS Fig. 5 Spartaeus thailandica sp. n., holotype 9: A, dorsal; B, carapace, lateral; C, leg I; D, epigyne. legs pale yellow-brown with vague sooty annuli. Spination of legs I: metatarsi v 2-2-1, p 0-0-1; tibiae v 6-4-6; femora p 0-1-1, d 0-2-1. Palps: pale yellow with dark amber tarsi and tibiae. Epigyne (Fig. 5D): thinly clothed in fine hairs, vulva not examined. Dimensions (mm): total length 8-4; carapace length 3-2, breadth 2-72, height 2-08; abdo- men length 5-08; eyes, anterior row 2-44, middle row 1-96, posterior row 2-18; quadrangle length 1 -64 (5 1 per cent of carapace length). Ratios: AM : AL : PM : PL :: 1 8 : 1 1 : 8 : 1 1 ; AL-PM-PL :: 8-15; AM : CL :: 18 : 5. DISTRIBUTION. Thailand. MATERIAL EXAMINED. Thailand: Dui Sutep, 1100m, holotype 9, 13.U959 (B. Degerbol) (UZM. K0benhavn, Pr. 2110). Genus YAGINUMANIS gen. n. DEFINITION. Medium to large spiders ranging from about 7-0 to 9-6 mm in length. Sexual dimorphism not marked, patterns fairly well defined (Fig. 6A). Carapace (Fig. 6A, C): moderately high, longer than broad, widest at level between coxae II and III; fovea long and sulciform, apex almost level with posterior margin of posterior lateral eyes. Eyes: with moderately large lenses set on moderately pronounced tubercles; anteriors subcontiguous with apices more or less level in frontal view and moderately recurved in dorsal; anterior medians largest; anterior laterals more than half diameter of anterior medians; posterior medians relatively large, positioned closer to and more or less on optical axis of anterior laterals; posterior laterals as large as anterior laterals and pos- itioned inside lateral margins of carapace when viewed from above; posterior ocular quad- rangle broader than long and wider behind; entire quadrangle about 45 per cent of carapace SPIDER SUBFAMILY SPARTAEINAE 1 53 length. Clypeus: of medium height. Chelicerae: moderately robust with strong lateral con- dyles; more or less parallel and slightly inclined anteriorly; fang moderately robust and curved; promargin with three teeth, retromargin with five or six denticles. Maxillae: moder- ately long, slightly diverging with outer distal margins rounded. Labium: about as long as broad and about half maxillae length. Sternum (Fig. 6D): elongate scutiform. Abdomen: elongate ovoid with four indistinct apodemal spots; spinnerets moderately long, posteriors moderately robust and slightly longer than robust anteriors, medians slender and shorter than anteriors. Legs: moderately long and slender, in females first pair slightly more robust; spines numerous and moderately strong; claws pectinate, tufts present; scopulae absent. Male palps: fairly large, dark and moderately complex with poorly developed interlocking protuberances; patellae with rudimentary anterodorsal tubercle; tibiae with robust ventral and retrolateral apophyses, the latter bearing a strong lobe; cymbium with distal scopulae, a small basal tubercle and slight lobe on retrolateral margin; embolus short, slender and arising distally; distal haematodocha a membraneous patch (M,); tegulum bulbous with peripheral seminal ducts a pleated distal element M3 and an irregular sclerotised pit-like furrow; median haematodocha, subtegulum and basal haematodocha not examined. Epigyne: moder- ately distinct and protruding with some frilling anteriorly; median openings obscured by blackish red surrounds; introductory ducts short, wide and poorly defined; spermathecae also ill-defined, somewhat pear-shaped with posterior portion partly rolled-up and bearing fertilisation ducts. TYPE SPECIES. Boethus sexdentatus Yaginuma. ETYMOLOGY. Named in honour of Dr Takeo Yaginuma; the gender is masculine. DIAGNOSIS. From other genera in the subfamily by details of the secondary genitalia (Fig. 6E, G-I, J) and geographical distribution. Yaginumanis sexdentatus (Yaginuma) comb. n. (Fig. 6A-J) Boethus sexdentatus Yaginuma, 1967: 54, holotype 9, paratype rf, Ohtemon-Gakuin University, Osaka [not examined]. Shinkai & Hara, 1975: 16. Matsumoto, Shinkai & Ono, 1976: 95; Yaginuma, 1977:398. DIAGNOSIS. By geographical distribution, the structure of the palp in males (Fig. 6E, J) and by the presence of dark reddish copulatory openings on the posterior margin of the protruding epigynal plate in females (Fig. 61). REMARKS. Yaginuma's original description is excellent and the species is redescribed here only for the sake of completeness. Male from Idzu, in fair condition. Carapace: cephalic part and thoracic sides dark amber lightly tinged and mottled black with middle of thorax paler, more or less as in (Fig. 6A); clothed in fine whitish hairs with brownish ones on sides. Eyes: with black surrounds except anterior medians; fringed by whitish hairs. Clypeus: clothed in fairly coarse pale amber hairs and edged with scattered long brownish ones. Chelicerae: orange-brown with sooty markings on basal and middle regions; thinly clothed in long fine whitish, and pale brown hairs; pro- margin with three teeth, retromargin with five or six denticles. Maxillae and labium: yellow- brown with inner distal margins of maxillae and labial tip whitish. Sternum: pale yellow-brown with slightly darker margins; thinly clothed in fine pale hairs. Coxae: pale yellow-brown. Abdomen: generally pale yellow-brown with vague sooty markings; dorsum clothed in recumbent fine whitish hairs interspersed with scattered stiff pale amber ones, upper sides clothed in short dark brownish hairs forming a pattern as shown in (Fig. 6A), lower sides clothed in fine whitish hairs with venter dark greyish clothed in fine pale amber ones; spinnerets yellow-brown with some black on outer sides of anteriors and posteriors. Legs: generally yellow-brown with indistinct annuli on metatarsi III and IV; spines moder- ately strong and numerous. Spination of legs I: metatarsi v 2-2-2, p 0-0-1, r 0-0-1; tibiae 154 F. R. WANLESS Fig. 6 Yaginumanis sexdentatus (Yaginuma), rf: E, palp, ventral; F, cheliceral teeth, inner view; J, palp, retrolateral; 9: A, dorsal; B, maxillae and labium; C, carapace, lateral; D, sternum; G, vulva, outer view; H, vulva inner view; I, epigyne. v 2-2-2, p 0-1-1, d 1-1-0, r 0-1-1; patellae p 0-1-0, r 0-1-0; femora p 0-0-1, d 0-2-4. Palp (Fig. 6E, J). Dimensions (mm): total length 6-96; carapace length 3-12, breadth 2-32, height 1-64; abdo- men length 3-8; eyes, anterior row 1-98, middle row 1-74, posterior row 1-84; quadrangle length 1-36 (43 per cent of carapace length). Ratios: AM : AL : PM : PL :: 15-5 : 9 : 6-5 : 9; Al^PM-PL :: 8-12; AM : CL :: 1 5-5 : 6. Female from Idzu, in fair condition. Essentially similar to d1 except for the following: Cara- pace: with paler indistinct and uneven marginal band from clypeus to level of coxae II-III. Clypeus: clothed in long white hairs. Chelicerae: amber with median sooty transverse band; SPIDER SUBFAMILY SPARTAEINAE 155 shiny; thinly clothed in fine pale amber hairs; promargin with three teeth retromargin with five. Legs: spination of legs I: metatarsi v 2-2-2; tibiae v 2-2-2, p 0-1-0; femora p 0-0-1, d 0-2-3. Palps: femora and patellae yellow-brown with whitish hairs, tibiae and tarsi yellow- brown with yellow-brown hairs. Epigyne (Figs 6G-I): clothed in fine whitish hairs. Dimensions (mm): total length 7-12; carapace length 3-08, breadth 2-36, height 1-68; abdo- men length 4-12; eyes, anterior row 2-04, middle row 1-76, posterior row 1-91; quadrangle length 14 (45 per cent of carapace length). Ratios: AM : AL : PM : PL :: 15-5 : 9 : 6-5 : 9; AL-PM-PL :: 7-12; AM : CL :: 15-5 : 6. VARIATION. Another d1 measures 6-3 mm total length, 2-76 mm carapace length, while 99 vary from 6-96 to 9-6 mm total length, 2-84-3-16 mm carapace length (seven specimens). DISTRIBUTION. Japan. MATERIAL EXAMINED. Japan, Idzu, Shizuoka Prefecture (nr. Mt. Fuji), 2d"cf, 799, (purchased from S. Akiyama, 5.vi.l910) (BMNH. 191 1.12.12.208-366 part). Genus TARAXELLA gen. n. DEFINITION. Spiders of medium size, i.e. between 4-0 and 8-0 mm in length. Males with conspicuous markings (Fig. 7 A), but extent of sexual dimorphism unknown. Carapace (Fig. 7 A, B): high, longer than broad, widest at level of coxae II; fovea long and sulciform, apex level with centre of posterior median eyes; clearly marked with broad encirc- ling band. Eyes: with large lenses set on moderately well developed tubercles; anteriors con- tiguous with apices weakly procurved in frontal view and moderately recurved in dorsal; anterior medians largest; anterior laterals more than half diameter of anterior medians; pos- terior medians relatively large, positioned slightly closer to and more or less on optical axis of anterior laterals; posterior laterals as large as anterior laterals and positioned inside lateral margins of carapace when viewed from above; posterior ocular quadrangle broader than long and wider behind; entire quadrangle about 57 per cent of carapace length. Clypeus: moder- ately high. Chelicerae: moderately robust; inclined anteriorly and slightly divergent; fang moderately slender and curved; promargin with six or seven teeth, retromargin with eight or nine denticles. Maxillae: moderately long, more or less parallel with outer distal margins rounded. Labium: longer than broad and about half maxillae length. Sternum (Fig. 7E): elon- gate scutiform. Abdomen: elongate avoid; spinnerets moderately long, posteriors moderately robust and more or less as long as robust anteriors, medians slender and slightly shorter than anteriors. Legs: moderately long and slender; spines numerous and moderately strong; claws pectinate; tufts present; scopulae absent. Female palps: unknown. Male palps: moderately large and complex with dorsal interlocking tubercle and recess on tibiae/cymbial joint; femora slightly bowed; patellae with slight anterodorsal tubercle; tibiae slightly excavated retrolaterally, with anterodorsal tubercle, a large ventral apophysis and retrolateral apophy- sis bearing a lightly sclerotised flange, also, between ventral and retrolateral apophyses a tuft of stout setae; cymbium with distal scopulae and basal depression opposite tibial antero- dorsal tubercle; embolus short, slender and arising apically, but largely hidden by apophysis 'x' and anterior margin of tegular furrow; distal haematodocha forming a white mem- braneous area M, bearing a large delicate fan-shaped process, another membraneous region (?) M2 lies between apophyses 'x' and 'y'; tegulum bulbous with peripheral seminal ducts looping distally, massive apophyses 'x' and 'y' the latter possibly homologous with M3 and a heavily sclerotised crescent- shaped furrow; median haematodocha, subtegulum and basal haematodocha not examined. Epigynes: unknown. TYPE SPECIES. Taraxella solitaria sp. n. ETYMOLOGY. The genus name is an arbitrary combination of letters; the gender is considered to be feminine. DIAGNOSIS. Distinguished from other genera in this subfamily by the presence of palpal apophyses 'x' and 'y' (Fig. 7G) and encircling carapace band (Fig. 7A). 156 F. R. WANLESS Tar axel I a sol it aria sp. n. (Fig. 7A-G) DIAGNOSIS. By the broad encircling carapace band and massive palpal tegular apophyses V and y (Fig. 7G). Female. Unknown. Male holotype, in good condition. Carapace (Fig. 7A, B): orange-brown suffused and mottled black with broad encircling creamy white band; irregularly clothed in dark amber hairs, mostly rubbed, with a few fine whitish ones in the encircling band. Eyes: with black sur- rounds except anterior medians; fringed by amber hairs with whitish ones around anteriors. Clypeus: pale yellow with broad vertical black bands below anterior median eyes; shiny. Chelicerae: amber suffused and mottled black with inner basal region grading to yellow- brown; shiny; thinly clothed in brownish hairs; promargin with six or seven teeth, retro- margin with eight or nine. Maxillae and labium (Fig. 7D): yellow-brown. Sternum: (Fig. 7E): pale yellow with darker margins; thinly clothed in brownish hairs. Coxae: pale yellow- brown, anteriors faintly tinged with some black. Abdomen: yellow-brown tinged and mottled black; clothed in dark amber hairs particularly on sides; spinnerets whitish yellow with Fig. 7 Tamxella solitaria sp. n., holotype rf: A, dorsal; B, carapace, lateral; C, cheliceral teeth, inner view; D, maxillae and labium; E, sternum; F, palp, retrolateral; G, palp, ventral. Abbrevi- ation: e, embolus. SPIDER SUBFAMILY SPARTAEINAE 157 anteriors and posteriors tinged black. Legs: moderately long and slender with numerous spines; generally yellow-brown with blackish femora and vague blackish annuli on metatarsi and tibiae. Spination of legs I: metatarsi v 2-1-1, p 1-2-1, d 0-0-2, r 1-0-0; tibiae v 2-2-2, p 1-0-1, d 2-1-0, r 0-0-1; patellae p 0-1-0; femora d 0-2-4. Palp (Fig. 7F, G): the embolus can be seen just protruding beyond the edge of apophysis V (arrowed, Fig. 7G). Dimensions (mm): total length 6-0; carapace length 2-64; breadth 2-16, height 1-88; abdo- men length 3-2; eyes, anterior row 2-18, middle row 1-8, posterior row 2-04; quadrangle length 1-52 (57 per cent of carapace length). Ratios: AM : AL : PM : PL ::18 : 10 : 6 : 10; AL-PM-PL :: 9-9-5; AM : CL :: 18 : 6. DISTRIBUTION. East Malaysia, Sarawak. MATERIAL EXAMINED. Sarawak, Gunung Mulu National Park, Melinau Gorge, under dead wood in limestone forest, holotype rf, l.v.1978 (F. R. Wanless, R.G.S./Sarawak Government Expedition) (BMNH, 1982.1.11.1). Genus MINTONIA gen. n. DEFINITION. Spiders small to medium in size, i.e. total length between 2-0 and 8-0 mm. Mark- ings sometimes distinctive, but extent of sexual dimorphism uncertain as most species only known from one sex. Carapace: moderately high, longer than broad, widest at level between coxae II-IH: fovea long and sulciform, apex near centre or posterior margin of posterior lateral eyes. Eyes: with moderately large lenses set on low tubercles; anteriors more or less contiguous with apices level or slightly procurved in frontal view and moderately recurved in dorsal; anterior medians largest; anterior laterals greater than half diameter of anterior medians; posterior medians relatively large, positioned closer to and on or near optical axis of anterior laterals; posterior laterals about as large as anterior laterals^ and set inside lateral margins of carapace when viewed from above; posterior ocular quadrangle broader than long and wider behind; entire quadrangle occupying between 48 and 62 per cent of carapace length. Clypeus: low to moderately high. Chelicerae: small to medium in size, slightly more robust in female; slightly inclined anteriorly and more or less parallel; fang moderately strong and curved; pro- margin with three teeth, retromargin with five to seven denticles. Maxillae: moderately long, generally parallel with rounded outer distal margins. Labium: as long as broad or slightly longer than broad, about half maxillae length. Sternum (Figs 8B; 10E): more or less elongate scutiform. Abdomen: elongate ovoid; spinnerets moderately long, posteriors slender and sometimes longer than robust anteriors, medians slender and slightly shorter than anteriors. Legs: moderately long and slender, first and second pairs slightly more robust in females; males usually with femoral organ, a minute amber spot or tubercle on underside of femora I; spines numerous and moderately strong; claws pectinate; tufts present, scopulae absent. Female palps: moderately robust with distal claw. Male palps: moderately complex and interspecifically distinct, moderately hirsute with dorsal interlocking tubercles weak or lack- ing on cymbial/tibial joint and weak to pronounced on patellae; tibiae more or less excavated retrolaterally with moderately large ventral apophyses and complex retrolateral apophyses of various forms, some with secretory openings; cymbium with distal scopulae, sometimes modified distally to accommodate embolic region or basally to protect retrolateral apophysis; embolus of various forms arising apically; distal haematodocha forming poorly defined mem- braneous region M, which is often only apparent in prolateral view, region M2 either appar- ently lacking or bearing a slender delicate process (Fig. 8H); tegulum usually subovoid with peripheral seminal ducts, a delicate translucent ledge or lobe-like process M3 rarely sclero- tised, and usually with a small lightly sclerotised crescent-shaped furrow; median haema- todocha a membraneous sac only evident in expanded palps, subtegulum a ring-like sclerite at distal end of basal haematodocha (examined only in M. ramipalpis). Epigynes: inter- specifically distinct; sometimes with anterolateral frilling; opening positioned centrally with or without a short median septum and sometimes with sclerotised posterior margin; 158 F. R. WANLESS introductory ducts not evident; spermathecae rounded with fertilisation ducts on posterior margins. TYPE SPECIES. Mintonia tauricornis sp. n. ETYMOLOGY. The genus name is an arbitrary combination of letters; the gender is considered to be feminine. DIAGNOSIS. Males by the development of the palpal tegular ledge M3, e.g. (Figs 8H: 9C; 12E; 14B). Females with more difficulty by details of the epigynes. Key to species of Mintonia Males (those of nubilis unknown) 1 Embolus with pronounced basal prong (Fig. 1 1 C arrowed) (Singapore) . . . protuberans sp. n. (p. 1 62) Embolus without basal prong 2 2 RTA long and sinuous with short lateral prong (Fig. 14B) (Java, Sarawak, Sumatra) . . . ramipalpis (Thorell) (p. 1 66) - RTA otherwise 3 3 RTA comprised of two long slender prongs (Fig. 9C) (Kalimantan) . . mackiei sp. n. (p. 160) RTA otherwise 4 4 RTA with lateral lobe or condyle (Fig. 13B arrowed) (Sarawak) . melinauensis sp. n. (p. 165) - RTA otherwise 5 5 RTA long slender and curving (Fig. 8F) (Sarawak) tauricornis sp. n. (p. 158) - RTA robust, distally bifid (Fig. 12D) (Sarawak) breviramis sp. n. (p. 164) Females (those of mackiei, melinauensis and protuberans are unknown) 1 Epigyne with thin dark median ridge (Fig. 1 OF) (Kalimantan). . . . nubilis sp. n. (p. 161) Epigyne without thin dark median ridge 2 2 Epigynal opening with blackish T-shaped mark or blotch (Fig. 1 5 A) (Java, Sarawak, Sumatra) . . . ramipalpis (Thorell) (p. 168) Epigynal opening without T-shaped mark or blotch 3 3 Posterior rim of epigynal opening resembling buffalo horns (Fig. 8D) (Sarawak) . . . tauricornis sp. n. (p. 1 59) Posterior rim of epigynal opening tube-like and curving (Fig. 12B) (Sarawak) . . . breviramus sp. n. (p. 165) Mintonia tauricornis sp. n. (Figs 8A-H; 32E, F; 35B) DIAGNOSIS. Distinguished by the curved retrolateral tibial apophysis in males (Figs 8F, H), and by the horn-like rim of the epigynal opening in females (Fig. 8D). Male holotype, in fair condition. Carapace (Fig. 8G): dark orange-brown lightly tinged black in eye region with vague yellowish brown markings on thoracic part; shiny and weakly irides- cent under some angles of illumination; irregularly clothed in recumbent black lanceolate hairs on sides of thorax, otherwise rubbed. Eyes: with black surrounds except anterior medians; ventral rim of anterior row fringed by whitish hairs, otherwise rubbed. Clypeus: yellow-brown edged black; thinly covered in light brownish hairs below anterior medians with dense fringes of long white hairs below anterior laterals and outer margins of anterior medians which sweep inwards covering cheliceral bases. Chelicerae: yellow-brown, shiny; basal half densely white haired; promargin with three teeth retromargin with seven. Maxillae and labium: pale yellow-brown lightly tinged with some black. Sternum: shape more or less as in 9; pale yellow with darker margins; thinly clothed in fine hairs. Coxae: pale yellow. Abdomen: similar to 9, but more slender; pale yellow; rubbed. Legs: moderately long and slender with numerous spines and minute pale amber spot (femoral organ) on under side SPIDER SUBFAMILY SPARTAEINAE 159 Fig. 8 Mintonia tauricornis sp. n., holotype d: F, palp, retrolateral; G, carapace, lateral; H, palp, ventral. Paratype 9: A, dorsal; B, sternum; C, carapace, lateral; D, epigyne; E, cheliceral teeth, inner view. of femora I; generally yellow-brown becoming darker distally except for femora I which is suffused with black and tibiae III which has a black proventral stripe. Spination of legs I: metatarsi v 2-2-0, p 1-0-1, d 0-1-0, r 1-0-1; tibiae v 2-3-2, p 0-1-0, d 3-3-0; patellae p 0-1-0, r 0-1-0; femora d 0-2-4. Palp (Figs 8F, H; 32E, F; 35B): the lobe M2 is not as conspicuous as illustrated. Dimensions (mm): total length 4-48; carapace length 2-04, breadth 1-8, height 1 -4; abdomen length 2-44; eyes, anterior row 1-68, middle row 1-44, posterior row 1-64; quadrangle length 1-24 (60 per cent of carapace length). Ratios: AM : AL : PM : PL :: 13-5 : 8 : 4-8 : 7-5; AL- PM-PL :: 7-5-10; AM : CL :: 13-5 : 5. Female paratype, in fair condition. Carapace (Fig. 8A, C): eye region amber tinged black, sides and thorax pale yellow with blackish markings; shiny and weakly iridescent under some angles of illumination; rubbed. Eyes: generally as in d1. Clypeus: fringed by long white hairs below anterior median eyes. Chelicerae: yellow-brown, shiny with scattered yellow-brown hairs along inner margins; promargin with three teeth, retromargin with six or seven (Fig. 8E). Maxillae and labium: as in d. Sternum (Fig. 8B): as in d. Coxae: pale yellow. Abdomen: 1 60 F. R. WANLESS whitish grey with sooty markings; rubbed. Legs: moderately long and slender with numerous spines; light yellow-brown grading to yellow-brown distally. Spination of legs I: metatarsi v 2-2-0, p 1 -0- 1 , d 0-2-2, r 1 -0- 1 ; tibiae v 2-3-2, p 1 - 1 -0, d 0- 1 -0, r 1 - 1 -0; patellae p 0- 1 -0, r 0-1-0; femora d 0-2-4. Epigyne (Fig. 8D): clothed in fine golden hairs. Dimensions (mm): total length 5-76; carapace length 2-2, breadth 1 -84, height 1 -4; abdomen length 3-36; eyes, anterior row 1-76, middle row 1-53, posterior row 1-74; quadrangle length 1 -29 (58 per cent of carapace length). Ratios: AM : AL : PM : PL :: 14 : 8 : 5-5 : 8; AL-PM- PL:: 8-9-5; AM CL::14:2. VARIATION. A paratype