Brienomyrus (Brienomyrus) microcephalus (Günther, 1867)
Species overview
Small to medium sized, elongate fish with rather long anal fin and a slender caudal peduncle. Head moderately tapering, straight, snout short, rounded, blunt. Blackish-grey.
Size observed: 141 mm SL.
B. microcephalus(measurements)
Taxonomic description
-Body elongate, laterally compressed, body depth 17-24 % SL, greatest depth close to anal fin, head length 16-25 % SL, head depth 11-16 % SL, 57-83 % body depth. outline of back more or less straight, upper profile of head convex, underside of head concave, below opercular region convex.
-Snout rounded, slightly protruding mouth, 17-27 % head length, 26-43 % postorbital length.
-Mouth slightly subterminal, 12-18 % head length, its edge below posterior nostril, upper jaw on a level with base of pectoral fin.
-Chin inconspicuous, without appendage or swelling.
-Teeth feebly notched, 6/6.
-Nostrils circular, nearly midway between eye and tip of snout, anterior on a level with centre of eye, posterior with its lower rim; axis of nostrils cutting axis of head at an angle of about 45°.
-Eye small, 6-13 % head length, 9-20 % postorbital length.
-Opercular cleft 33-44 % head length, 47-69 % head depth.
-Dorsal fin 14-17 fin-rays, base of A 11-16 % SL, anal fin 28-33 rays, base of A 26-37 % SL; D originating well behind origin of A, ending well before end of A. Predorsal length 62-69 % SL, preanal length 51-58 % SL.
-Pectoral obtusely pointed, 11-18 % SL, extending to base of pelvic fin. V is closer to P than to A.
-Caudal small, pointed, its scaled lobes rounded, shorter than membrane. 59-77 scales in lateral line, 12 round caudal peduncle.
-Caudal peduncle 13-18 % SL, its depth 3-5 % SL, 25-33 % its length.
-Coloration, microcephalus : »Brown; head and fins black«; longianalis »Purplish brown, more or less profusely speckled with blackish; fins dark brown.«
Type locality
Mormyrus microcephalus :»Gabon, River Ogowe«,
Marcusenius longianalis : »Sapelle Station, at the junction of the Ethiops and Jamieson Rivers«, Niger Delta.
Distribution
Gabon, Ogowe river and tributaries; Lower Niger and Niger delta and some coastal basins of Guinea and Sierra Leone (Lévêque, Paugy and Teugels, 1990.)