Hippopotamyrus discorhynchus (Peters, 1852)
Species overview
Medium sized fish, body rather deep, oval in profile, base of dorsal fin longer than that of anal. Size observed: 223 mm SL.
H. discorhynchus(measurements)1
H. discorhynchus(measurements)2
Taxonomic description
-Body rather short, body depth 27-37 % SL, greatest depth close to pelvic fin; head short, head length 20-28 % SL, head depth 21-28 % SL; upper profile of head convex, underside of head slightly convex.
-Outline of back curved, bases of fins inclusive, outline of belly slightly curved. Snout rounded, 17-27 % head length, 29-48 % postorbital length, slightly protruding mouth which is small and slightly subterminal, its edge below anterior to rim of eye, upper jaw on a level with lower edge of opercular cleft.
-Chin with slight submental swelling.
-Teeth notched, 5/5-6.
-Nostrils separate, circular, anterior slightly above posterior, the latter on a level with lower rim of eye; halfway between tip of snout and eye. Diameter of eye as long or a little more than length of snout, 16-24 % head length, 27-43 % postorbital length.
- Opercular cleft curved, 29-46 % head length, 31-43 % head depth.
-Dorsal fin 29-36 fin-rays, anal 23-27 rays, base of D 23-36 % SL, base of A 17-24 % SL; D originating well anterior, ending posterior to A. Predorsal length 53-60 % SL, preanal length 56-64 % SL.
-Pectoral fin pointed, extending to base of pelvic fin or up to its mid. V is closer to P than to A.
-Caudal fin obtusely pointed, membranous as well as scaled lobes. 58-70 scales in lateral line, 12 (14) round caudal peduncle.
-Caudal peduncle 16-23 % SL, its depth 5-8 % SL, 26-43 % its length.
Coloration:
»Dark olive or brownish above, silvery white beneath«; H. cubangoensis, according to original description: »Reddish brown all over, head often yellowish, a wide black bar between D and A; fins blackish or greyish.« H. grahami: »Dark brownish above, silvery white below, countershaded, with or without irregular darker markings.«
Type locality
H. discorhynchus: »Zambese, Loc. Tette«.
M. tanganicanus: »Sumbu and river at Msamba: Tanganyika Lake«. (08° 31 ‘ S 30° 29 ‘ E)
M. cubangoensis: »Riv. Cubango, Angola«. Cubango = Okawango, (18° 53 ‘ S 22° 24 ‘ E)
M. grahami : »? near mouth of Kagera river (0° 57’ S, 31° 46 ‘E)«, Lake Victoria.
Distribution
Upper Zaïre basin, Tanganyika and Nyassa (Nyasa, Malawi) lakes, Zambese and Cubango rivers, Lake Victoria and affluent rivers, Kyoga basin.