Campylomormyrus alces (Boulenger, 1920)
Species overview
Larger species, greatest body depth in front of unpaired fins, head trunk-shape snouted, short, snout steeply bent down but rather short, caudal peduncle short. Dark brown on back, flanks and belly silvery, countershaded, between unpaired fins a dark bar, juveniles with white markings. Size observed: 318 mm SL, 370 mm TL.
C. alces(measurements)
Taxonomic description
-Body rather short, laterally compressed, body depth 27-35 % SL greatest depth in front of anal fin.
-Head length, measured as distance upper end of opercular cleft across the eye to outline of front, i. e. without snout, 16-23 % SL, 18-27 % SL, snout inclusive, head depth 19-23 % SL, 64-79 % body depth.
-Outline of back straight, of belly slightly convex, upper profile strongly convex, underside of head strongly concave.
-Snout, measured from margin of eye to tip 50-79 % head length, snout not inclusive; trunk-shaped, almost vertically bent down, distally compressed and at the mouth about as deep as diameter of eye*.
-Chin fleshy, with a short barbel, about as long as diameter of eye.
-Mouth width 5-6 % head length, snout inclusive, running parallel to underside of head, edge of mouth far away from nostrils, upper jaw well below head. Postorbital region about as long or longer as preorbital region.
-Teeth 3-4/4, truncate.
-Nostrils oval, separate, on a level with the lower margin of the eye; distance between the nostrils about three times in the distance posterior nostril to eye; axis of nostrils cutting axis of head at an angle of less than 30°.
-Eye diameter three times in snout length.
-Opercular cleft 29-34 % head depth, S-shaped.
-Dorsal fin 31-34 rays, base of D 26-31 % SL, anal fin 33-35 rays, base of A 30-34 % SL; D originating behind origin of A, ending before end of A. Predorsal length 57-59 % SL, preanal length 49-53 % SL.
-Pectoral fin pointed, extending to middle of pelvic fin.
-Caudal fin with long pointed membranes, scaled portion short, pointed. 70-75 scales in lateral line, 12 round caudal peduncle.
-Caudal peduncle, 16-22 % SL, its depth 4-7 % SL, 22-42 % its length. *) The extreme shape of the snout changes with age/size of the fish, in juveniles it is much less obvious.
-Coloration »Back dark brown, silvery on the flanks, slightly countershaded, borders of fins light brown to yellowish, followed by a blackish band, rest of fin rays and membranes more or less transparent. Between origins of D and A a blackish rhomboid patch, border on either side by a white band. In juveniles these patterns are much more expressed as in larger specimens. They even have a curved white band behind the head and a white line between that marking and the white band in front of the black rhombus.
Type locality
»Stanley Falls« to day: Chutes Ngalième, Democratic Republic of Congo (00° 50 ‘ N 25° 50 E).
Distribution
Congo basin (Democratic Republic of Congo, Angola)