Pollimyrus petricolus (Daget, 1954)
Species overview
Small fish, body elongate, head longer than body depth as well as its depth, snout truncate, mouth slightly subterminal, unpaired fins nearly equal in length of base; caudal peduncle rather deep, caudal fin rounded. Uniform dark. Size observed: 110 mm SL.
P. petricolus(measurements)
Taxonomic description
-Body elongate, laterally compressed, cross section oblong-oval, body depth 24-28 % SL, greatest depth at middle of trunk.
-Head length 26-31 % SL; head depth 19-23 % SL, 78-86 % body depth.
-Outline of back and of belly rather straight, upper profile of head convex, underside of head concave. Bases of unpaired fins running moderately steep to caudal peduncle.
-Snout truncate, feebly protruding mouth, 13-19 % head length, 21-30 % postorbital length.
-Mouth 14-20 % head length, slightly subterminal, its edge below posterior rim of eye, upper jaw on a level with upper edge base of pectoral fin.
-Chin inconspicuous.
-Teeth notched, 5-8/7-9.
-Nostrils separate, circular, anterior nostril on a level with lower rim of lens, 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 12-19 % head length, 18-29 % postorbital length.
-Opercular cleft curved, 21-28 % head length, 28-35 % head depth.
-Dorsal fin 20-23 fin-rays, base of D 22-25 % SL, anal fin 23-26 rays, base of A 22-25 % SL, origin of D more or less opposite origin of A, end of D opposite end of A; predorsal length 60-63 % SL, preanal length 59-63 % SL.
-Pectoral fin rounded, extending slightly beyond base of pelvic fin. V is closer to P than to A.
-Caudal fin rounded, the scaled lobes too, extending to half the length of the membranous part. 59-72 scales in lateral line; 16-20 round caudal peduncle.
-Caudal peduncle 15-19 % SL, its depth 5-7 % SL, 30-50 % its length.
-Coloration »Uniform blackish with sometimes the belly lighter«. Varying with area of distribution, darker in the Upper Niger, much lighter in the Middle Niger basin, where the body is speckled with many small melanophores. Fin rays dark, fin membranes colourless, except for the bases of the unpaired fins.
Type locality
»Markala, (Soudan)«. (13° 39 ‘ N 6° 05 ‘ W) Mali.
Distribution
»Upper and Middle Niger basin, downstream to Lake Kainji (10° 30 ‘ N 4° 35 ‘ E)«
Electric organ discharges
P. petricolus(EOD)