Petrocephalus binotatus Pellegrin, 1924
Species overview
Small fish, body short, deep, head shorter than body depth, snout round, protruding mouth. Head with three aggregations »rosettes«, of cutaneous sensory organs. A large, circular spot below the first rays of the dorsal fin, a crescent-shaped blackish band on the base of the caudal fin, body countershaded. Size observed: 96.5 mm SL, 118 mm TL.
P. binotatus(measurements)
Taxonomic description
-Body small, short, quite deep, strongly laterally compressed, body depth 40 % SL, greatest depth at origin of anal fin.
-Head length 27-31 % SL; head depth 23-28 % SL, 64-79 % body depth.
-Outlines of back and belly slightly convex, upper profile and underside of head convex; base of unpaired fins steeply running to caudal peduncle.
-Snout rounded, blunt, short, 11-21 % head length, 17-33 % postorbital length.
-Mouth wide, 15-26 % head length, inferior, its edge below centre of eye, upper jaw on a level with lower edge of opercular cleft.
-Chin without inconspicuous.
-Teeth notched, 15/24.
-Nostrils closely together, upright-oval, on a level between lower rim and centre of eye; posterior nostril at the rim of the eye; axis parallel axis of head.
-Eye diameter 18-27 % head length, 157-186 % snout length, 27-46 % postorbital length. Three rosettes, aggregations of electroreceptors, on the head.
-Opercular cleft strongly curved, 36-46 % head length, 40-50 % head depth.
-Dorsal fin 30 fin-rays, base of D 22-24 % SL, anal fin 35 rays, base of A 29-39 % SL, origin of D behind origin of A, end of D before end of A; predorsal length 57-63 % SL, preanal length 53-57 % SL.
-Pectoral fin pointed, extending to 2/3 the length of pelvic fin. V is closer to P than to A.
-Caudal fin pointed, scaled part short, narrow. 39 scales in lateral line; 12 round caudal peduncle.
-Caudal peduncle 15-18 % SL, its depth 5-6 % SL, 27-40 % its length.
-Coloration »Bright brown above, silvery on flanks and belly; a large, round, dark spot below the first rays of dorsal fin, a blackish. crescent-shaped band on the base of caudal fin; first rays of dorsal fin dark, fins generally greyish«.
Type locality
»Ikengo (fleuve Congo)«Democratic Republic of Congo.
Distribution
Congo basin.