Mormyrus subundulatus Roberts, 1989
Species overview
Large fish, body moderately elongate, head with funnel-shaped snout (tubular-snouted), mouth terminal with protruding lower lip. No conspicuous cutaneous sensory organs below the eye (but see below). Pectoral fin not extending to pelvic fin. Uniform black or bronze, depending on local conditions. Most similar to Mormyrus rume (see also there).
Size observed: 271 mm SL.
Taxonomic description
-Body moderately elongate, laterally compressed, cross section oblong-oval, greatest depth at origin of dorsal fin.
-Outline of back - before dorsal fin - convex, at base of D feebly convex, upper profile of head more or less straight, underside of head concave, outline of belly, base of anal fin inclusive, slightly convex, no step at base of pelvic fin.
-Snout tapering, bluntly funnel-shaped, tip of upper jaw on a level with lower edge of opercular cleft.
-Mouth small terminal, with thick lips and protruding lower lip, edge of mouth far away from anterior nostril.
-Chin with moderate submental swelling, lower jaw less deep than upper jaw. Number and shape of teeth not indicated.
-Nostrils separate, posterior one oval, anterior nostril on a level with centre of eye, posterior with lower margin, distance between nostrils about 1/3 their distance from eye, axis of nostrils makes an angle of 40° to axis of head.
-Eye moderate, orbital cavity ovoid. No conspicuous tuberous organs below the eye.
-Opercular cleft curved.
-Dorsal fin 60-71 fin-rays, anal fin 16-18 rays, origin of D far before origin of A, about halfway between bases of pectoral and pelvic fin, end of D far posterior to end of A.
-Pectoral fin obtusely pointed, extending to about 2/3 the distance to pelvic fin, its origin at lower edge of opercular cleft. V is slightly closer to P than to A..
-Caudal fin obtusely pointed to rounded, the scaled lobes covering about 3/4 of the entire fin. 87-99 scales in lateral line; 21-26 round caudal peduncle. Depth of caudal peduncle 5-8 % SL. (The original description gives very few proportional measurements, species is very close to Mormyrus rume, differences mainly concern the EODs).
-Coloration »Colour in life predominantly black (Bandama) or bronze (Tano)« i.e. dependant on local conditions.
Type locality
»Mainstream of R. Bandama near Station Biologique de Lamto, Côte d’ Ivoire; R. Bandama á Béoumi, Côte d’ Ivoire; R. Tano at Samreboi, Ghana«. (Bandama river 5°10 ‘ N 04° 58 ‘ W; Béoumi 7° 40 ‘ N 5° 34 ‘ W; Tano river 5° 07 ‘ N 2° 58 ‘ W )
Distribution
»Rivers Bandama, Ivory Coast and Tano, Ghana, perhaps also R. Sassandra, Ivory Coast«.
Electric organ discharges
Biphasic, head positive, +/–
Total duration 0.961 ± 0.093 msec, n = 5, (not significantly different from the EOD of Mormyrus rume with 0.966 ± 0.109 msec.). Conductivity 93.5 µS, pH 6.8 in natural environment.
Relative amplitude of the phases, i. e. ratio phase 1 (+) to phase 2 (– ) = 0.144 (range 0.113-0.203, n = 5) compared to M. rume 0.445 (range 0.398-0.494, n = 9), Student’ s test: t = 13.52, P < 0.0001, DF = 12 (Crawford and Hopkins, 1989). Ratio total voltage / voltage phase 2 (– ) 1.132(range 1.108-1.198), for M. rume 1.441 (range 1.318-1,5).
M. subundulatus(EOD)