Marcusenius thomasi (Boulenger, 1916)
Species overview
Medium-sized fish, body moderately elongate, head uneven blunt-snouted, dorsal fin quite short, anal fin quite long, caudal peduncle slender. Size observed: 205 mm SL.
M. thomasi(measurements)
Taxonomic description
-Body moderately elongate and deep, body depth 24-30 % SL, greatest depth near anal fin.
-Head length 19-22 % SL, head depth 16-20 % SL, 58-77 % body depth.
-Outlines of back and belly more or less straight, upper profile of head strongly convex, underside of head concave.
-Snout rounded, blunt, 20-29 % head length, 37-49 % postorbital length.
-Mouth terminal, 12-18 % head length, its edge below anterior nostril, upper jaw on a level with lower rim of eye.
-Chin with a strong globular swelling, directed somewhat downwards.
-Teeth notched, 5/4-6.
-Nostrils separate, circular, closer together than away from the eye, posterior nostril on a level with lower rim of the eye, anterior with centre of eye, their axis cuts axis of head at an angle of 45-60°.
-Eye diameter 17-23 % head length, 29-44 % postorbital length.
-Opercular cleft curved, 29-37 % head length, 34-46 % head depth.
-Dorsal fin 22-27 fin-rays, base of D 13-20 % SL, anal fin 37-43 rays, base of A 28-33 % SL, origin of D well behind origin of A, end of D well before end of A, the base line of D, prolonged would meet the base of the last ray of A; predorsal length 53-62 % SL, preanal length 46-54 % SL.
-Pectoral fin pointed, extending to tip of pelvic fin (in the type specimen V is missing). V is closer to P than to A.
-Caudal fin with long pointed membranous lobes, scaled lobes narrow, pointed, rather short. 80-88 scales in lateral line; 12 round caudal peduncle.
-Caudal peduncle 15-22 % SL, its depth 4-5 % SL, 19-33 % its length.
-Coloration »Brownish in general; head, some spots on the body and the basal portions of the unpaired fins are darker«.
Type locality
»N. Sherbro district, Sierra Leone«, (07° 33 ‘ N 12° 42 ‘ W).
Distribution
Only known from Guinean region: Guinea, Liberia, Sierra Leone.