Petrocephalus microphthalmus Pellegrin, 1908
Species overview
Very small fish, body short and deep, head slightly longer or as long as deep, snout as long or longer than diameter of eye, mouth inferior. No conspicuous aggregations of cutaneous sensory organs on the head. Pectoral fin obtusely pointed. Silvery with darker back, countershaded, first rays of unpaired fins with blackish. Size observed: 80 mm SL.
P. microphthalmus(measurements)
Taxonomic description
-Body short, strongly laterally compressed, body depth 30-39 % SL, greatest depth between pelvic and anal fin.
-Head length 24-30 % SL; head depth 24-28 % SL, 70-86 % body depth.
-Outline of back and belly slightly convex, upper profile and underside of head convex; bases of dorsal and anal fin running steeply to caudal peduncle.
-Snout rounded, short, 13-21 % head length, 22-32 % postorbital length.
-Mouth 19-29 % head length, inferior, its edge below centre of eye, upper jaw on a level with upper edge base of pectoral fin.
-Chin inconspicuous.
-Teeth notched 10/20.
-Nostrils closely together, anterior one more circular, posterior wider, upright-oval, both on a level slightly above lower rim of the eye; axis parallel to axis of head.
-Eye diameter 13-20 % head length, 21-33 % postorbital length. No rosettes, aggregations of electrorecpetors, on the head.
-Opercular cleft curved, extending over base of pectoral fin, 35-48 % head length, 36-52 % head depth.
-Dorsal fin 19 fin-rays, base of D 16-20 % SL, anal fin 28 rays, base of A 19-31 % SL, origin of D well behind origin of A, end of D well before end of A; predorsal length 59-65 % SL, preanal length 52-57 % SL.
-Pectoral fin pointed, length, extending over more than 3/4 the length of pelvic fin. V is closer to P than to A.
-Caudal fin pointed, scaled part short. 35 scales in lateral line; 10 round caudal peduncle. (Scale and fin-ray counts only of type available.) Caudal peduncle 19-23 % SL, its depth 5-7 % SL, 25-32 % its length.
-Coloration »Silvery, olive-brown above; dorsal and anal blackish anteriorly,« countershaded.
Type locality
»Ngomo, (Ogôoué)«
Distribution
Ogowe river (mouth 0° 49' S 4° 00' E) and Sanaga River (3° 55' N 9° 38'E), Gabon and Cameroon, respectively.
Electric organ discharges
P. microphthalmus(elec. organ)