Mormyrus caballus Boulenger, 1898
Mormyrus caballus bumbanus Boulenger, 1909
Species overview
Large fish, quite similar to Mormyrus c. caballus, body moderately elongate, rather deep, head strongly convex with funnel-shaped, downward bent snout, terminal mouth, underside of head concave; no conspicuous cutaneous sensory organs below the eye. Coloration countershaded with olive back and silvery belly.
Size observed: 295 mm SL, 338 mm TL.
M. cab. bumbanus(measurements)
Taxonomic description
-Body moderately elongate, laterally compressed, rather deep, cross section oblong-oval, depth of body 20-26 % SL, greatest depth at origin of dorsal fin.
-Head about as long as depth of body, 22-27 % SL; depth of head 16-21 % SL, 67-97 % depth of body.
-Outline of back , from neck to caudal peduncle, convex, upper profile of head strongly convex, above eye up to tip of snout rather straight; tip of snout strongly convex again. Underside of head concave, outline of belly up to caudal peduncle slightly convex, without a step at base of anal fin.
-Snout funnel-shaped, blunt, slightly compressed, 30-48 % head length, 54-97 % postorbital length.
-Mouth 12-17 % head length, terminal, directed forward, edge of mouth far away from anterior nostril, edge of upper jaw on a level with lower edge of opercular cleft.
-Chin with moderate submental swelling, lower jaw and upper part of snout about equal in depth.
-Teeth feebly notched, 5-7/8-10.
-Nostrils separate, both more or less oval, closer to eye than to end of snout; in larger specimens anterior nostril clearly below level of lower margin of eye, posterior below it, in smaller specimens posterior nostril on a level with eye; axis of nostrils cutting axis of head at an angle of about 45-60°.
-Eye diameter 13-23 % head length, 28-40 % postorbital length. Opercular cleft strongly curved, 31-45 % head length, 40-66 % depth of head.
-Dorsal fin 62-70 fin-rays, base of D 43-54 % SL, anal fin 25-26 rays, base of A 15-19 % SL, origin of D far before origin of A, above base of pelvic fin, end of D far behind end A; predorsal length 33-38 % SL, preanal length 51-60 % SL.
-Pectoral fin obtusely pointed, extending to base of pelvic fin or slightly beyond, base of P close to lower edge of opercular cleft. V is slightly closer to P than to A.
-Caudal fin large with pointed membranes, the scaled lobes pointed, extending over 3/4 of the entire fin. 93-100 scales in lateral line; 14-16 round caudal peduncle.
-Caudal peduncle 13-17 % SL its depth 4-6 % SL, 29-44 its length.
-Coloration »Olive above, silvery white beneath«, countershaded.
Type locality
M. c. bumbanus: »Bumba River at Assobam, South Cameroon (Congo System)«; M. habereri: »Dscha, sek. Nebenfluss des Kongo, Kamerun«, Dja River, Cameroon; M. jae: »Ja River« (Mouth of Dja River: 2° 02 ‘ N 15° 12 ‘ E).
Distribution
»Northern tributaries of the Congo River: Congo from Ubangi to Stanleyville (Kisangani, Democratic Republic of Congo), Ja and Bumba Rivers«.
»Luapula, Moero and Upper Lufira basin« Democratic Republic of Congo. About 8-12° S, 25-30° E.