Mormyrus iriodes Roberts and Stewart, 1976
Species overview
Medium-sized fish, body both moderately elongate and deep, back rounded; head short, snout blunt, uneven, not downward bent, slightly protruding mouth. No conspicuous cutaneous sensory organs below the eye. Caudal peduncle slender, caudal fin large. Iridescent in coloration. Size observed: 270 mm SL.
M. iriodes(measurements)
Taxonomic description
-Body moderately elongate, laterally compressed, cross section oblong-oval with a crest on the back, body depth 22-25 % SL, greatest depth between origins of dorsal and pelvic fin.
-Head length 21-22 % SL; head depth 17-18 % SL, 73-79 % body depth.
-Outline of back (dorsal fin inclusive) convex with a hump at origin of D, upper profile of head strongly convex, underside of head rather concave, outline of belly slightly convex up to base of anal fin which is smoothly bent towards the caudal peduncle.
-Snout short, uneven-blunt, slightly protruding mouth, 27-34 % head length, 47-59 % postorbital length, edge of upper jaw on a level with lower edge of opercular cleft.
-Mouth 11-18 % head length, slightly subterminal, 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 less deep than upper part of snout. Number of teeth not indicated in original description.
-Nostrils separate, posterior one oval, anterior on a level with lower rim of eye, their axis cutting axis of head at an angle of about 30°.
-Eye diameter 10-16 % head length, 47-59 % postorbital length. No conspicuous cutaneous sensory organs below the eye.
-Opercular cleft curved, 29-32 % head length, 36-40 % head depth. Number of fin-rays in both D and A not indicated, base of D 45-48 % SL, base of A 15-20 % SL, origin of D far before origin of A, opposite base of pelvic fin, end of D far behind end A; predorsal length 36-38 % SL, preanal length 52-55 % SL.
-Pectoral fin pointed, extending to base of pelvic fin. V is slightly closer to A than to P or equally distant.
-Caudal fin pointed, the scaled lobes extending to 4/5 of the length of the membranous lobes. Scale counts are missing in the original description.
-Caudal peduncle slender, 17-18 % SL, its depth 4-5 % SL, 22-27 % its length.
-Coloration »Live specimens with a pearly iridescence and delicate pinkish, violaceous and bluish-green reflections«.
Type locality
»Zaïre River mainstream near Inga hydroelectric dam (5° 31.5 ‘ S 13° 57.5 ‘ E)«, Rapids of Congo River, Central Zaïre district. Democratic Republic of Congo.
Distribution
Type locality.