Hippopotamyrus wilverthi (Boulenger, 1898)
Species overview
Medium-sized fish, body deep, back strongly curved: humpbacked, head round-snouted, nearly as long as deep, snout rounded, short. Yellowish. Size observed: 248 mm SL, 292 mm TL
H. wilverthi(measurements)
Taxonomic description
-Body rather deep, laterally compressed, body depth 29-41 % SL, depending on length of the fish, greatest depth near dorsal fin.
-Outline of back strongly convex in front of dorsal fin, in larger specimens forming a hump, concave on nape, base of dorsal fin straight. Upper profile of head strongly convex, underside of head concave, belly slightly convex.
-Head short, nearly as long as deep, head length 23-25 % SL, head depth 20-26 % SL, 60 70 % body depth.
-Snout rounded, not or slightly protruding mouth, snout length 20-26 % head length, 40-70 % postorbital length.
-Mouth 14-28 % head length, terminal or slightly subterminal, its edge below posterior nostril, upper jaw on a level with upper edge base of pectoral fin.
-Chin with strong submental swelling.
-Teeth very small, almost hidden in the thick gums, truncate or slightly notched, 3/6.
-Nostrils separate, circular, anterior on a level with centre of eye, posterior below it, but well above lower rim of eye, their axis arranged at an angle of about 45° relative to axis of head.
-Eye moderately large, its diameter 14-23 % head length, 25-42 % postorbital length.
-Opercular cleft curved, 28-36 % head length, 30-35 % head depth.
-Dorsal fin 38-40 fin-rays, base of D 33-39 % SL, anal fin 25-27 rays, base of A 19-23 % SL, origin of D before origin of A, its end behind end of A; predorsal 50-55 % SL, preanal length 57-61 % SL.
-Pectoral fin pointed, extending to middle of pelvic fin. V is closer to P than to A.
-Caudal fin with pointed membranous lobes and obtusely pointed scaled lobes, 2/3 in length. 61-68 scales in lateral line; 12 round caudal peduncle.
-Caudal peduncle slim, 15-19 % SL, its depth 4-7 % SL, 23-37 % its length.
-Coloration, wilverthi : »Yellowish.« (Most probably with darker back, countershaded.); macrops : »Dark brown above, lighter beneath«, countershaded.
Type locality
wilverthi : »Matadi, lower Congo, and Upoto, upper Congo.« Democratic Republic of Congo (Matadi: 05° 49 ‘S 13° 27 ‘E, Upoto: 02° 00 ‘N 21° 30 ‘E).
macrops : »Upper Congo.« Democratic Republic of Congo.
macroterops (partim): »Poko«, Riv. Bomekendi, affluent de l’Uélé. (03° 07 ‘N 26° 55 ‘E).
Distribution
Congo basin.