Petrocephalus catostoma tanensis Whitehead and Greenwood, 1959
Species overview
Very small sized fish, according to original diagnosis »?agrees in all characters with P. c. catostoma but has more dorsal fin-rays (III. 22-25 [mode 24])«. Head with three aggregations, »rosettes«, of cutaneous sensory organs. Silvery, back darker, belly lighter, countershaded. Size observed: 68.5 mm SL.
P. cat. tanensis(measurements)
Taxonomic description
-Body moderately short and deep, strongly laterally compressed, body depth 30-33 % SL, greatest depth above origin of anal fin.
-Head length 29-34 % SL; head depth 26-29 % SL, 83-97 % body depth.
-Outlines of back and belly slightly convex, upper profile and underside of head convex; bases of unpaired fins running rather steeply to caudal peduncle.
-Snout rounded, short, 14-22 % head length, 20-35 % postorbital length.
-Mouth width 25 % head length, inferior, its edge below posterior rim of eye, upper jaw on a level between base of pectoral fin and underside of head.
-Chin inconspicuous.
-Teeth notched, 10-14/17-24.
-Nostrils closely together, upright-oval, on a level with lower rim of lens of eye; axis parallel axis of head.
-Eye diameter 17-22 % head length, 26-39 % postorbital length. Three rosettes, aggregations of electrorecpetors, on the head. Opercular cleft curved, 32-48 % head length, 33-47 % head depth.
-Dorsal fin 25-28 fin-rays, base of D 20-24 % SL, anal fin 26-29 rays, base of A 23-28 % SL, origin of D behind origin of A, end of D before end of A; predorsal length 56-60 % SL, preanal length 52-58 % SL.
-Pectoral fin pointed, extending to middle of pelvic fin. V is closer to P than to A.
-Caudal fin pointed, scaled part short. 35 scales in lateral line; 12 round caudal peduncle.
-Caudal peduncle 17-25 % SL, its depth 7-10 % SL, 32-58 % its length.
-Coloration silvery, upper side more dusky, underside white, countershaded; fins colourless.
Type locality
»Garsen, Tana River, Kenya« (2° 36 ‘ S 40° 07 ‘ E).
Distribution
»Confined to the Tana river and probably not occurring above Garissa (600 feet above sea level)« Kenya.