Mormyrus hasselquistii Valenciennes, 1846
Species overview
Large fish, body moderately elongate, head about as long as body depth with short, blunt, snout funnel-shaped, feebly downward bent, mouth terminal. No conspicuous epidermal sensory organs below the eye. Caudal peduncle rather deep. Silvery or greyish, countershaded. Size observed: 480 mm SL, 1115 g.
M. hasselquistii (measurements)
Taxonomic description
-Body moderately elongate, laterally compressed, cross section oblong-oval, body depth moderate, 18-222 % SL, greatest depth at origin of dorsal fin.
-Head length 21-29 % SL; head depth 12-19 % SL, 62-89 % body depth.
-Outline of back (dorsal fin inclusive) slightly convex, upper profile of head convex up to end of snout, underside of head concave; outline of belly slightly convex, without step at base of pelvic fin.
-Snout blunt, funnel-shaped, moderately compressed, short, slightly protruding mouth, feebly bent down, 23-29 % head length, 36-46 % postorbital length, edge of upper jaw more or less on midline of head.
-Mouth 12-17 % head length, slightly subterminal, rather deeply incised, its edge far away from anterior nostril, edge of upper jaw on midline of head.
-Chin with moderate submental swelling, lower jaw lees deep than upper part of snout.
-Teeth notched, 6-16/10-22.
-Nostrils separate, anterior one circular, posterior oval and on a level with lower rim of eye, their axis cutting axis of head at an angle of about 40°.
-Eye small, slightly oval, its diameter 9-13 % head length, 13-21 % postorbital length. No conspicuous epidermal sensory organs below the eye.
-Opercular cleft curved, 36-45 % head length, 53-80 % head depth.
-Dorsal fin 63-82 fin-rays, base of D 52-59 % SL, anal fin 16-20 rays, base of A 8-14 % SL, origin of D far before origin of A, even closer to base of P than base of V, end of D far behind end A; predorsal length 32-38 % SL, preanal length 61-67 % SL.
-Pectoral fin obtusely pointed, extending over 1/2 to 2/3 its distance to pelvic fin. V is about equally distant from P and A.
-Caudal fin more or less rounded, the scaled lobes obtusely pointed, covering about 3/4 of the entire fin. 83-97 scales in lateral line; 26-34 round caudal peduncle.
-Caudal peduncle 8-12% SL, its depth 6-7% SL, 55-82 % its length.
-Coloration »Generally silvery, changing into more or less greyish; back much darker, grey-yellowish, -greenish or -blackish; belly white, yellowish-white or light-grey«. Countershaded.
Type locality
M. hasselquistii (herse, cashive): »Nil«, M. agnus: »?aus dem Volta-Fluss bei Kete Kratschi in Togo«, M. guentheri: »West Africa, Niger«, M. felixi: »Cameroun«.
Distribution
Nile, Chad, Senegal, Middle Niger, Volta, Gambia, Mono basins, some rivers and lagoons Ivory Coast; North and North-West Cameroon.
Remark
M. felixi is known only from the type, most likely from River Benoue, Cameroon, where M. hasselquistii also is well known, hence it is most probably not a valid species.