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THE A leA JOU L

OF

(Afr. J Trop. Hydrobiol. Fish)

Yo. 1 1994 THE OF THE (PISCES: SILUROIDEA) IN LAKE KAINJI,

N.G. WIlLOUGHBY Kainji Research Project P.M.B. 666, New Bussa, Nigeria

Present Address: Fisheries Research Ojjicer, Lower Shire, P/B Chiromo, Malawi

ABSTRACT This paper considers the taxonomy of most of the Synodontis spp. present in the main drainage basins of West Mrica. The first section consists of a key to the sixteen known to occur in Lake Kainji. Nigeria. A second section considers species which are reputed to live in the area and therefore might occur in the lake. It is suggested that several of the latter group are synonymous with better known species.

INTRODUCTION (pers.comm.) consider thflt the differences Thispaperis concernedwith the taxonomy cited by Poll do notwarrant generic status, of a group of commercially important cat and thatsince there is little osteological data fishes in the recentlyformed man-made lake, to support it, this divisioN is notjustified. Lake Kainji, ontheRiverNigerinNigeria,West Consequentlythe original classification will Africa. be adhered to in the present work. Systematicswork on the genus Synodontis The key considers only those species startedwith BOULENGER's (1911) catalogue known to be present in Lake Kainji. Other ofthosespeciespresentin the BritishMuseum specieswhich, itis thought, mightoccur, are (NaturalHistory). Thetaxonomyofthe genus described later. Thus the majority of the has recently been revised by POLL (1971), species of Synodontis to be found in West who divided the genus into three genera, Africaare consideredin this paper. However, Synodontis, Hemisynodontis and for more extensive descriptionsand figures, Brachysynodontis, the last two ofwhich are the works of BOULENGER (1911), POLL monospecific. POLL (op. cit.) based this (1971),LEWIS (1974) and WILLOUGHBY division largel)'upon theextended opercular (1974) should be consulted. openings ofS. membranaceusand S. batensoda Synodontisare small to medium sized cat which he placed in Hemisyno-dontis and fishes (Figure 1). They have three pairs of Brachysynodontis respectively. However, well-developed barbels, the two mandibular the presentauthorand DrP.H. Greenwood pairs being branched.The head is enclosed of the British Museum (Natural History) in a heavy bony casing, the cephalo-nuchal 26 N.G. WllLOUGHBY

shield. The first ray of the and of Key to the species of Synodontis recorded of each pectoral fin is modified to form a stout from Lake Kainji serrated spine, which can be locked at right 1.(a) No gap between end of rayed dorsal (b) H1 angles to the body axis. In addition to the fin and adipose fin. Ventral surface rid~ rayed dorsal fin, there is an adipose fin, often darker than dorsal surface in life. low ...... 2 l (b) Gap present between end of rayed (c) Hl dorsal and adipose fin. Dorsal surface will darker than ventral surface in life. and ...... 3 1.4­ 2. (a) 7-16 mandibular teeth. Wide black witt , membrane running full length of max­ illary . Fins pale grey and DA( neve{, spotted.... .Synodontis 6. (a) 6-' ., membranaceus (GEOFFROY-ST.­ time HILAIRE 1809) (pOLL, 1971,placesthis don standard lenath species in the genus Hemisynodontis) Colc (b) 35-60 mandibular teeth. Membrane on maxillary barbel tapers from base to at tip. Caudal fin always spottedwithblack. (b) 15 ·1 ...... 1.5t (RUPPELL 1832) (POLL, 1971, ond« places this species in the genus Colo Brachysynodontis) maxillary tooth band spot! mandibular tootl1 band (c) 53-78 mandibular teeth. Maxillary Be barbels with tubercles or small ramifi­ 7. (a) Sn ~~~ma"lIary barbe' maxil'ary barbel membrane cations anda narrow membrane restricted Eye . outer mandIbular barbel to basal third. inner mandIbular barbel lengl ...... Synodontis (b) Snl t . resupinatus Eye« BOULENGER 1909 3. (a) Lower partofhumeral process bearing 8. (a) 12· spines tusel BOULENGER 1911. (See also S. omias). gold4 (b) Lower part of humeral process not of e) bearing spines

~. cour, . 4 xiphi Fig. 1. Synodontis Measurements. 4. (a) Maxillary barbels bearing fine rami- (b) 24· fications. Caudal fin red...... Synodontis tusel: large, which lacks supporting bony rays. The clarias (LINNAEUS 1758) oliv skin is without scales, butmay havevilli, which (b) Maxillarybarbelsunbranched. Caudal are small hair-like projections from the body fin neverred 5 viol, wall into the over-lying mucous covering. 5. (a) Humeral process rounded with no S. s ridge along lower margin. Both lobes KEY TO WEST AFRICAN SYNODONTIS SSP 27

Synodontis recorded of caudal fin edged with black (c) 29-49 mandibular teeth. Snout large, ji ...... 6 depressed and rounded. Colour dark en end of rayed dorsal (b) Humeral process sharply pointed with brown with darker spots ofeye diameter e fin. Ventral surface ridge (sometimes not prominent) along size or smaller. orsal surface in life. lower margin ., Synodontis , 2 ...... 7 gobroni DAGET 1954. See also S. between end of rayed (c) Humeral process obtusely pointed guttatus). lOse fin. Dorsal surface with n0 ridge along lower margin. Head 9. (a) 44-62 rnandibularteeth. Dorsal fin with entral surface in life, and body strongly compressed (height rays 1-5 prolonged into filaments. Colour ...... 3 1.4-1.6 times width). Body covered olive to brown with small dark spots. ular teeth. Wide black with fine vernliculated spots...... Synodontis ling full length of max- ...... Synodontis vermiculatus eupterus Fins pale grey and DAGET 1954. BOULENGER 1901 potted.... .Synodontis 6. (a) 6-9 mandibular teeth. Snout 1.8-2.1 (b) 23-43 mandibular teeth. Dorsal fin rs (GEOFFROY-ST.­ times post-orbital length. Filament on filaments absent or present on first ray ,(POLL,1971,placesthis dorsal spine shorter than spine. only 10 genus Hemisynodontis) Colour of body uniform grey. 1O.(a) Adipose fin small, approximately 25% mlarteeth. Membrane on ...... ,.... .Synodontissorex of standard length. Colour mid to dark leI tapers from base to GUNTER 1864 brown with dark spots of less than eye ~ways spotted withblack. (b) 15-23 mandibular teeth. Snout 1.2- diameter size on body and fins. .Synodontis batensoda 1.5 times post-orbital length. Filament ...... : Synodontis 1832) (POLL, 1971, on dorsal spine much longer than spine. nigrita CUVIERand VALENCIENNES ipecies in the genus Colour of body yellowish with dark 1940 (See also S. melanopterus.) ntis) spots Synodontisjilamentosus (b) Adipose fin medium sized, more than ibular teeth. Maxillary BOULENGER 1901 30%ofstandard length. Colour yellow, lbercles or small ramifi­ 7. (a) Snout 60% or more of head length. brown or olive, with or without spots. rrow membrane restricted Eye diameter less than 30% of snout ., 11 length. ll.(a) Body marked with dark spots larger ,.. , Synodontis (b) Snout 50% or less of head length. than eye diameter. Fins spotted or Eye diameter 30-70% ofsnout length. striped Syn 0 don tis ocellifer Rl909 ...... 9 BOULENGER 1900 'humeral process bearing 8. (a) 12-17 mandibular teeth. Snout ob- (b) Body and fins usually unspotted...... Synodontis budgetti tusely pointed with fleshy lips. Colour Spots minute when present. 12 1911. (SeealsoS. omias). golden yellow with dark brown spots 12.(a) Mandibular tooth band less than half of humeral process not of eye diameter size. as wide as maxillary tooth band. Dorsal s ., ,", Synodontis ::" surface of pectoral spine usually more courteti PELLEGRIN 1906 (See also S. coarsely ridged than ventral surface...... , 4 xiphias and S. labeo) Skin generally villose. Crest of rrbels bearing fine rami­ (b) 24-30 mandibular teeth. Snout ob- cephalonuchal shield immediately in lalfinred...... Synodontis tusely pointedbutlips not fleshy. Colour front of dorsal spine obtusely pointed. AEUS 1758) olive to brown with no spots...... " Synodontis rbels unbranched. Caudal ...... BLOCH-SCHNEIDER 1801 (See ...... , , 5 violaceus PELLEGRIN 1919 (See also also S. robbianus). ocess rounded with no S. solani). (b) Mandibular tooth band more than half lwer margin. Both lobes as wide as maxillary tooth band. Dorsal 28 N.G.WIl.LOUGHBY

surface of pectoral spine wi th ridges and it is unlikely that the two belong to the Synodont ofsamesize as on ventralsurface. Skin same species. S. xiphias closely resembles S. This: seldom bearing any villossities. Crest counetiin body proportions, barbel lengths, violaceus ofcephalonuchalshield immediately the humeral process, and also in the pos­ RiverNi! in front ofdorsal spine rounded. session of a flap of skin running longi­ KainjibyI ...... Synodontis tudinally between the inner mandibular byLELE: gambiensisGUNTHER 1864 barbels. S. couneti is the only West African unlikeaI Description ofSynodontisspp. reputed to occur Synodontis known to possess this flap, and areaofth in or near Lake Kainji: thus the evidence stron~ly suggests that from S. ; Synodontis omias GUNTHER 1864 S. xiphias and S. courteti are synonymous. 1. ~ , This species is very similar to S. budgetti, Synodontis labeo GUNTHER 1865 its maxill but may be distinguished from it by three This poorly known species was thought palemem characteristics (BOULENGER, 1911). by DAG&T (1954) to be synonymous with 2. .5 -1. 1. The presence ofanal'row membrane S. courteti, which it resembles in body form, ~. of S. vio on the basal third ofthemaxillary barbel size and colouration. However, the type 3. .5 of S. bUdgetti, and its absence in S. specimen of S. labeo has a blunt rounded darkerbl omzas. numeral process where as that of S. couneti or brown 2. The pelvic fins of S. omias reach is sharp; the maxillary barbels of S. labeo Synodontl beyond the origin ofthe analfin, while reach well beyond the origin ofthe pectoral This • ·1 those of S. budgetti do not. fin, while those of S. courteti seldom reach maybe 3. S. omias is thought to have between it; and the flap ofskin present between the ingch 41 and 58 mandibular teeth, while S. barbels of S. courteti is absent in S. labeo. 1. budgetti has between 45 and 64. While this evidence suggests that S. labeo the stan However, the type specimen of S. omias is aseparate species, more evidence is neces­ 25% or is a skeleton, and the species has only been sary to clarify its status. 2 positively identified by POLL (1971) from Synodontis guttatus GUNTHER 1865 in S. ni, one specimen. The widths of barbel mem­ POLL (1971) considers this little known are long branes and the lengths of fins are variable species to be distinguishable from S. gobroni like do t . in other Synodontis spp. and the mandibular by its body proportions, mandibular tooth 3. teeth are constantly being replaced as they number, and the absence ofvilli on the skin darkbr wear or break. DAGET (1954) considers the oftheformer. However, specimensofS. gobroni usually differences between the two to be minute and examined by the author spanned the ranges Exa of dubious taxonomic validity, and in the of both tooth numbers and body propor­ suggests opinion of the present author they are tions cited by POLL (op.cit) for the two with the / probably synonymous. species. Furthermore, the skin ofthe stuffed melanop Synodontis xiphias GUNTHER 1863 type specimen ofS. guttatus bears evidence, itfrom The type specimen of this species was notably on the head, ofhaving been densely Synodon shown byPOLL (1971) to be misleading, its villose, andthe lipsare coveredwith papillae. This snout being an artefact caused by the taxi­ Both these features are presenton S. gobroni, butisrl dennist,andPOLL (1971) consideredthespecies and a villose head has notbeen observed on larybar to be synonymous with Synodontis any other species. Thus although the quality thewid labeoGUNTHER 1865. However, the humeral ofthe material makes positive identification maxill processes ofS. xiphiasand S. labeo has blunt, difficult, itis thought thatDAGET (1954) is the b rounded humeral processwhereas thatofS. correctin his suggestion chat the two species S. robh' counetidiffer considerablyin size and shape, are synonymous. KEY TO WEST AFRICAN SYNODONTIS SSP 29

t the two belong to the Synodontis soloni BOULENGER 1899 despite the removalofthe protective mucous hias closely resembles S. This species superficially resembles S. layer, and the spots present on its dorsal portions, barbel lengths, violaceus, and has been recorded from the surface are very similar to those ofjuvenile ~ss, and also in the pos­ River Nigerby FANG (1943) andfrom Lake S. schall. While it is thought possible that of skin running longi- Kainji by LELEK(1972). Thespecimenobtained the two species are synonymous, collection the inner mandibular by LELEKwas notexamined closely butwas ofmore material from the delta ofthe River is the only West African unlike any otherspecies obtainedfrom the , where S. TObbianusis thought to live, to possess this flap, and areaofthe lake. S. solonimay be distinguished is necessary to test this hypothesis. : strong-ly suggests that from S. violaceus by three features. SUMMARY ourteti are synonymous. 1. S. solonihasa blackmembranealong JNTHER 1865 Despite a recent revision of the genus its maxillary barbel, while S. violaceus has a Synodontis, there are several taxonomic pro­ )Wll species was thought pale membrane. blems which are not resolved. A key to the to be synonymous with 2. S. soloni has a naked skin while that sixteenspecies ofthisgenuswhichhave been resembles in body form, of S. violaceus is densely villose. found in Lake Kainji on the River Niger in Ion. However, the type 3. S. soloni is mottled or bloched with Nigeria, hasbeen constructed,and provides 'eo has a blunt rounded darker brown,whereas S. violaceushasolive additional information to thatfound in 0 ther here as that ofS. courleti or brown skin with no markings. keys by which to separate some of the llary barbels of S. labeo Synodontis melanopterusBOULENGER 1902 morphologicallyverysimilarspecies. he origin ofthe pectoral This species is similar to S. nigrita, but A second section considersspecieswhich S. courteti seldom reach may be distinguished from it by the follow­ are reputed to live in the area and might be kin present between the ingcharacteristics. encountered in the lake. Ofthese species it ~eti is absent in S. labeo. 1. The adipose fin is 30% or more of is possible that the following pairs are syn­ :e suggests that S. labeo the standard length of S. melanopterus, but onymous: "more evidence is neces­ 25% or less of S. nigrita. ;tatus. S. budgetti and S. omias 2. Thefirst ray ofthedorsal finis longest GUNTHER 1865 S. courteti and S. xiphias in S. nigrita whereas the second and third S. gobTOni and S. guttatus msiders this little known are longin S. melanopterus, producinga sail­ S. schall and S. robbianus ~uishablefrom S. gobroni like dorsal fin similar to that of S. eupterus. ACKNOWLEDGEMENTS ions, mandibular tooth 3. The bodyofS. melanopterusis uniform I would like to acknowledge the help of lsence ofvilli on the skin darkbrown in colour,while thatofS. nigrita Mr. D. Eccles, who critically read the manu­ ,er,specimens ofS. gobroni usually possesses small dark brown spots. scriptand made several useful suggestions. thorspanned the ranges Examination of preserved material The work was carried out while on a grant lbers and body propor­ suggests that the larger adipose fin together ~L provided by the Overseas Development (op.cit) for the two with the absence ofspots on the body of S. Administration ofthe British Government. re, theskin ofthe stuffed melanopteruswould be sufficientto separate guttatus bears evidence, it from S. nigrita under field conditions. l, ofhaving been densely Synodontis TObbianus SMITH 1873 Ire covered with papillae. This species is very similar to S. schall, are presenton S. gobroni, butisreputed to have a membraneonits maxil­ asnotbeen observed on lary barbelwhich is equal to orgreater than hus although the quality thewidth ofthebarbel.The membraneon the ~s positive identification maxillary barbel ofS. schallis narrower than Itthat DAGET (954) is the barbel. The type specimen of ,tion rhat the two species S. TObbianus retains a few villi on its sides 30 N.G. WllLOUGHBY ASPE( TANG REFERENCES Lewis, D.S.C. (1974). an illustrated key to the MIODc ~ Boulenger, G.A. (1911). Catalogue ofthe Fresh­ fishes of Lake Kainji. (Mimeographed \ water Fishes ofAfrica in the British report to Overseas Development Ad­ Museum (Natural History). Trustees of ministration, London). - the British Museum, London, 526p Poll, M. (1971). Revision des Synodontis Daget, J. (1954). Les poissons du Niger Africains. Musee Royal de I'Afrique Superieur. Mem. l.F.A.N. No. 36. Centrale, Tervuren, Belgium. SOOp. Fang, P. W. (1943). Surcertains types peu connus Willougby, N.G. (1974). The ecology of the de Cyprinides des collections du museum genus Synodontis (Pisces; Siluoidea) de Paris (111). Bull. Mus. Hist. Nat. IS in Lake Kainji, Nigeria. (Unpublished ABSTRACT , Ph.D. thesis to the University of Juveniles of j p.399-405. (cit. DAGET 1954) 1967-1968. Tl Leleka (1972). Kainji Lake, Research Project, Southampton, England). the Kariba I'll Nigeria. Fish populations ofKainjiLake, samples of th trends in their development and period of fou " increased. It utilisation. FI: SF/NIR 24. Technical Lake Tangany Report 2. FAO, UN, Rome. The growth r Limnothrissa. l' September, fc

INTRODUC The abse vorous, pela middle Zam new lake be formation oj clupeid sard Tanganyika fill this vacar t . in lengthwer and transpc species of Limnothriss Stolothrissa t is the more only Limnotl near the sho ers. Unpubli~ Division of Zambia] shO'i

I. The Depafl of Zambia was sp. becoming the De