Boulengeromyrus knoepffleri Taverne and Géry, 1968
Species overview
Large fish, up to 40 cm and more in length; body moderately elongate and deep head moderately tapering and bent, snout rounded, long, slightly bent down. Countershaded with dark back and brighter belly or uniform brown, usually a dark bar between dorsal and anal fin. Size observed: 298 mm SL (in the types; may attain more than 400 mm).
B. knoepffleri(measurements)
Taxonomic description
-Body moderately elongate, laterally compressed, body depth 28-32 % SL, greatest depth above origin of anal fin.
-Head 29-35 % SL, head depth 18-24 % SL, 61-80 % body depth.
-Outline of back slightly convex, upper profile of head rather straight, underside of head concave, outline of belly slightly convex; bases of dorsal and anal fins steeply running down or up, respectively, to caudal peduncle.
-Snout long, its end flattened, 30-32 % head length, 48-53 % postorbital length.
-Mouth terminal, 9-14 % head length, edge of mouth before anterior nostril, upper jaw on a level with lower edge opercular cleft.
-Chin with submental swelling, without appendage.
-Teeth incisiform, slightly notched, 3-5/4-6.
-Nostrils separate, a little closer to the eye than to the tip of the snout, posterior nostril oval, below the anterior, their axis cutting axis of snout at an angle of about 60°.
-Eye small, 6-11 % head length, 10-18 % postorbital length, orbit oval, main axis horizontal.
-Opercular cleft strongly curved, 29-44 % head length, 49-83 % head depth.
-Dorsal fin 23-24 fin-rays, base of D 16-20 % SL, anal fin 28-31 rays, base of A 22-24 % SL, origin of D behind origin of A, end of D before end of A; predorsal length 60-65 % SL, preanal length 55-62 % SL.
-Pectoral fin wide, pointed, extending to the tip of pelvic fin or nearly so.
-Caudal fin rather large, with pointed lobes, the scaled lobes about half as long as the entire fin. 56-62 scales in lateral line, 12 around caudal peduncle.
-Caudal peduncle 18-24 % SL, its depth 6 % SL, 27-37 % its length.
-Coloration Brownish at the back, fading into silvery at the body, or into a lighter brown, depending on the environment. Often, in particular in juvenile specimens, a dark bar between D and A.
Type locality
»Rapides de Loa-Loa (00°27’ N, 12°48’ E) en aval de Makokou, Gabon«.
Distribution
Only known from the Ivindo river, Gabon, and its tributaries, where it is quite abundant, in particular around rapids and frequently caught in fish traps. Name in the local languages is ‘Epoko Poko’ in Bakota and ‘Mbamzok’ in Fang.
Electric organ discharges
B. knoepffleri(elec. organ)
B. knoepffleri(EOD)