Brienomyrus (Brevimyrus) niger (Günther, 1866)
Species overview
Medium sized fish, body rather short, moderately deep, head parabolic in profile, about as long as deep. mouth subterminal, pectoral fin very long, caudal peduncle relatively short and deep. Silvery or back blackish brown, countershaded, sometimes speckled dark brown. Size observed: 141 mm SL.
B. niger(measurements)
Taxonomic description
-Body moderately elongate, quite stocky, its profile from origin of dorsal fin to origin of anal parabolic. Body depth 26-34 % SL, greatest depth at about middle of body.
-Head in profile parabolic, 22-27 % SL, head depth 18-25 % SL, 57-92 % body depth.
-Outlines of back and belly slightly convex, upper profile of head convex, underside of head convex, sometimes slightly concave.
-Snout short, 11-21 % head length, 18 - 35 % postorbital length, slightly protruding.
-Mouth 14-24 % head length, slightly subterminal, edge of mouth below anterior nostril, upper jaw on level with midline of head.
-Chin thick, but without swelling; teeth notched, 3-5/6-10.
-Nostrils circular, posterior on level with lower rim of the lens, anterior above posterior, about 1/2 snout length away, close to front contour. Axis of nostrils cutting axis of head at an angle of about 30°. Diameter of eye 9-19 % head length, 14-34 % postorbital length.
-Opercular cleft S-shaped, 26-41 % head length, 31-45 % head depth, its upper edge at axis of body.
-Dorsal 14-20 fin-rays, its base 16-22 % SL, anal fin 24-30 rays, its base 20-28 % SL; D originating behind origin of A, ending before end of A. Predorsal length 60-67 % SL, preanal length 56-62 % SL. Slope of bases of D and A rather steep relative to axis of body.
-Pectoral fin rather long, 19-29 % SL, pointed, extending to tip of pelvic fin. V is closer to P than to A.
-Caudal obtusely pointed, its scaled portion rounded, about 1/3 its length. 43-58 scales in lateral line, 12 round caudal peduncle.
-Caudal peduncle 13-23 % SL, its depth 6-8 % SL, 26-53 % its length.
-Coloration Uniform silvery or with blackish brown back - countershaded -, sometimes sides speckled with dark brown or with darker stripes along each series of scales.
Type locality
Brienomyrus niger: »Gambia«., Gnathonemus baudoni: »Gribingui«, (0° 26 ‘ N 12° 48 ‘ E), Marcusenius lhuysi »Dagana, Senegal«, (13° 31 ‘ N 15° 30 ‘ W); Marcusenius macularius: »Fort Sibut, Ubangi Shari«. (0° 30 ‘ S 17° 42 ‘ E).
Distribution
Gambia, Niger, Chad, Volta and Senegal basins, White Nile, coastal drainages of the Bay of Guinea, from Senegal to Rio Muni; Uele and Ubangi rivers.
Comment on taxonomy:
Synonymy of M. lhuysi with M, macularius is doubtful because in the latter taxon the posterior nostril is much closer to the eye than in P. lhuysi as well as in the species of the genus Brienomyrus, whereas in Pollimyrus the posterior nostril is always closer to the margin of the eye than to the anterior nostril, often even it »touches« the eye. Because of this here M. macularius Fowler, 1936 has been placed into the species Pollimyrus brevis (Boulenger, 1913) as suggested by Gosse, 1966.