Hippopotamyrus petherici (Boulenger, 1898)
Species overview
Medium-sized fish, body moderately short, quite deep, head moderately long, as long as deep or slightly shorter, snout rounded, feebly protruding mouth, dorsal fin much longer than anal. Countershaded with brown back and silvery belly, sometimes with a dark bar between origins of dorsal and anal fin. Size observed: 227 mm SL.
H. petherici(measurements)
Taxonomic description
-Body strongly laterally compressed, body depth 27-38 % SL, greatest depth above pelvic fin or at origin of dorsal.
-Head length 21-24 % SL; head depth 21-28 % SL, 66-82 % body depth.
-Outline of back from origin of dorsal fin up to nape strongly convex, nape feebly concave, upper profile of head convex, underside of head slightly concave, outline of belly slightly convex. Bases of unpaired fins moderately steep running to caudal peduncle.
-Snout blunt, rounded, feebly protruding mouth, 15-21 % head length, 25-35 % postorbital length.
-Mouth 13-19 % head length, slightly subterminal, its edge extending to a line below centre of eye, upper jaw on a level between base of pectoral fin and underside of head.
-Chin inconspicuous.
-Teeth notched or truncate when worn down, 5/6.
-Nostrils separate, circular, closer to each other than posterior nostril to the eye; anterior nostril slightly above lower rim of eye, posterior nostril on a level with lower rim of eye. Axis of nostrils cutting axis of head at an angle of about 30°.
-Eye diameter 16-23 % head length, 28-42 % postorbital length.
-Opercular cleft slightly curved, 32-37 % head length, 29-40 % head depth.
-Dorsal fin 34-36 fin-rays, base of D 31-35 % SL, anal fin 24-26 rays, base of A 18-23 % SL, origin of D well before origin of A, end of D more or less opposite end of A; predorsal length 51-55 % SL, preanal length 58-62 % SL.
-Pectoral fin pointed, extending to middle of pelvic fin. V is well closer to P than to A.
-Caudal fin pointed, the scaled lobes obtusely pointed, extending to half the length of membranous lobes. 55-65 scales in lateral line; 12 round caudal peduncle.
-Caudal peduncle 19-24 % SL, its depth 7-8 % SL, 27-40 % its length.
-Coloration »Brown above, silvery white below, more or less speckled with darker; an ill-defined dark bar, extending obliquely from origin of dorsal to that of anal, sometimes present; dorsal fin, and sometimes also anal, brownish in front«. Countershaded.
Type locality
»Nil, Khartum,« Khartoum, Sudan (19° 36 ‘ S 32° 32 ‘ E)
Distribution
»Lower White Nile, Blue Nile (Abay, Bahr al Azraq: 15° 38 ‘ N 32° 31 ‘ E), Murchison Nile«.