Brienomyrus (Brienomyrus) ivindoensis new species
Species overview
Small to medium sized fish, body moderately elongate, snout rounded, blunt, less than half as deep as head depth, clearly bent down; eye and anterior nostril quite close to outline of head; body brown, with dark grey head, unpaired fins dark-brown at with lighter base. Size observed: 108 mm SL.
B. ivindoensis(measurements)
Taxonomic description
-Body rather elongate, laterally compressed, body depth 19-21 % SL, greatest depth at about middle of trunk.
-Head length 21-25 % SL, head depth 15-19 % SL, 82-92 % body depth.
-Outline of back straight, of belly straight or slightly rounded, upper profile of head feebly concave, underside of head concave.
-Snout moderately elongate, clearly bent down, 21-27 % head length, its depth about half the head depth; tip of snout round, slightly protruding mouth, which is slightly subterminal, 10-20 % head length; edge of mouth extending to a line half the distance between nostrils, upper jaw on a level with lower edge of opercular cleft.
-Chin moderately fleshy, without swelling or appendage.
-Teeth notched, 5 in upper, 6 in lower jaw.
-The nostrils are separate, circular, approximately at the level of the axis of the body, posterior nostril midway between eye and tip of snout, the anterior one very close to outline of snout and a little above the posterior; axis of nostrils cutting axis of head at an angle of less than 30ª.
-Opercular cleft slightly curved, 24-31 % head length, 32-42 % head depth.
-Eye small, 7-10 % head length, 10-15 % postorbital length.
-Fin rays in dorsal 21, base of D 17-20 % SL, anal 24-25 rays, base of A 21-24 % SL; origin of D posterior to the origin of A, both fins ending opposite to each other.
-Predorsal length 60-65 % SL, preanal length 56-61 % SL.
-Pectoral obtusely pointed, extending to base of pelvic. V closer to P than to A,
-Caudal fin obtusely pointed, proximal half scaled also obtusely pointed. 75-78 scales in lateral line, 12 scales around caudal peduncle.
-Caudal peduncle slender, 17-19 % SL, its depth 4-5 % SL, 21-28 % its length.
-Coloration, body dark-brown all over, head dark-grey, dorsal and anal fin dark-brown with small light-brown bases.
Type locality
»Rivière Ivindo, près de M’Passa, Makokou, Gabon.« (0° 25’ N, 12° 48’ E)
Distribution
Ivindo river, North Gabon (type locality).
Electric organ discharges
B. ivindoensis(elec. organ)
B. ivindoensis(EOD)
Triphasic discharges also have been observed, one and the same specimen may emit two different kinds of discharge. The duration is neither related to size nor to sex. See also B. curvifrons.
Water: temperature 19.9-22.8° C, conductivity 34-57 µS (Harder, unpublished.)