Marcusenius greshoffi (Schilthuis, 1891)
Species overview
Medium-sized fish, body moderately deep, head about as long deep, uneven blunt-snouted, eye quite large, upper rim close to front profile which is concave; quite uniform silvery with darker back.
Size observed: 216 mm SL.
M. greshoffi(measurements)
Taxonomic description
-Body laterally compressed, body depth 26-31 % SL, greatest depth close to dorsal fin.
-Head length 22-27 % SL, head depth 16-20 % SL, 56-67 % body depth.
-Outline of back slightly convex between dorsal fin and neck, continuing into a convex upper profile of head, (the concave upper profile of head of the type specimen of M. greshoffi is not typical), underside of head concave, outline of belly more or less straight.
-Snout obtusely pointed, 20-27 % head length, 39-52 % postorbital length.
-Mouth 11-17 % head length, terminal, its edge before nostrils, upper jaw on a level with lower rim of eye.
-Chin with a rather long globular swelling, directed forward or slightly downward. (Seems to be distorted in the type specimen of M. macrophthalmus due to preservation).
-Teeth truncate, 3/2-4.
-Nostrils separate, circular, anterior nostril on a level with centre of eye, posterior nostril on a level with lower rim of lens. Distance between nostrils about equal to distance from eye; axis of nostrils making an angle of about 45° to axis of head.
-Eye quite large, its diameter 19-31 % head length, 35-60 % postorbital length.
-Opercular cleft curved, 25-39 % head length, 35-51 % head depth.
-Dorsal fin 31-36 fin-rays, base of D 23-33 % SL, anal fin 29-32 rays, base of A 24-32 % SL, origin of D more or less opposite origin of A, end of D more or less opposite end of A; predorsal length 52-57 % SL, preanal length 55-60 % SL.
-Pectoral fin pointed, extending beyond half of pelvic fin. V is closer to P than to A.
-Caudal fin pointed, scaled lobes rather narrow, about half as long as membranes. 72-80 scales in lateral line; 12 round caudal peduncle.
-Caudal peduncle 17-23 % SL, its depth 4-5 % SL, 18-28 % its length.
-Coloration, shining silvery, olive on back, countershaded. »Uniform silvery with steel-blue reflexes on head and back« (M. macrophthalmus).
Type locality
M. greshoffi : »Kinshasa, Stanley-Pool«, to day Pool Malembo, Democratic Republic of Congo.
M. macrophthalmus : »Tshikapa (Kasaï)«, (06° 25 ‘S 20° 48 ‘E), Democratic Republic of Congo.
Distribution
M. greshoffi : Congo basin (Lower and Central Zaïre, Democratic Republic of Congo).
M. macrophthalmus : Kasaï River, Democratic Republic of Congo.