Pollimyrus plagiostoma (Boulenger, 1898)
Species overview
Medium-sized fish, body moderately short, deep, head about as long as deep, snout blunt, round to truncate, clearly protruding the inferior mouth; dorsal much longer than anal fin; caudal peduncle slender. Back brownish, belly silvery, countershaded.
Size observed: 183 mm SL.
P. plagiostoma(measurements)
Taxonomic description
-Body moderately short, strongly laterally compressed, deep, body depth 30-37 % SL, greatest depth above pelvic fin.
-Head length 21-26 % SL; head depth 23-27 % SL, 69-79 % body depth.
-Outline of back strongly convex, upper profile of head convex, underside of head concave; outline of belly slightly convex. Bases of unpaired fins moderately steep running to caudal peduncle.
-Snout rounded to truncate, 13-23 % head length, 27-38 % postorbital length.
-Mouth 14-18 % head length, inferior, its edge below centre of eye, upper jaw on a level between base of pectoral fin and underside of head.
-Chin inconspicuous.
-Teeth very small, feebly notched, 7-9/8-10.
-Nostrils separate, circular, anterior nostril on a level with lower rim of lens, posterior nostril very close to the eye, on a level slightly above lower rim of eye. Axis of nostrils cutting axis of head at an angle of less than 30°.
-Eye diameter 15-23 % head length, 24-45 % postorbital length.
-Opercular cleft curved, 21-32 % head length, 20-38 % head depth.
-Dorsal fin 31-35 fin-rays, base of D 30-37 % SL, anal fin 27-30 rays, base of A 24-28 % SL, origin of D well before to origin of A, end of D behind end of A; predorsal length 50-55 % SL, preanal length 56-61 % SL.
-Pectoral fin pointed, extending beyond middle of pelvic fin. V is much closer to P than to A.
-Caudal fin obtusely pointed, the scaled lobes extending to 1/2 or 2/3 the length of the membranous lobes. 55-70 scales in lateral line; 16 round caudal peduncle.
-Caudal peduncle slender, 16-22 % SL, its depth 3-5 % SL, 18-32 % its length.
-Coloration »Pale brown above, silvery below, fins greyish«.
Types locality:
»Matadi«. (5° 49’ S 13° 27 ‘ E) Zaïre Central, district of Democratic Republic of Congo.
Distribution
»Congo basin«.
Remark on taxonomy:
The length of the base of the dorsal fin is quite unique within the genus Pollimyrus, however the position of the posterior nostril close to the eye is typical for it.