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Dorsal spines (total): 18-19; Dorsal soft rays (total): 8-10; Anal spines: 3-3; Anal soft rays: 7-8. Diagnosis: The steeply sloped vomer, the small retrognathic jaw, and the presence of bicuspid teeth in the outer rows of both lower and upper jaws and enlarged conical teeth at the back of the jaws place this species in Tropheops (Ref. 119465). Tropheops biriwira, body depth 26.8-32.1% of standard length, cannot reliably be distinguished from other Tropheops on body depth, 23.6-34.5% (Ref. 119465). The breeding male of T. biriwira has green/light blue ground colouration with a green dorsal fin, while those of T. kumwera and T. kamtambo both have blue ground colouration and a blue dorsal fin; females of T. biriwira cannor reliably be distinguished from those of T. kumwera, but lack a black submarginal band in the dorsal fin that characterizes female T. kamtambo (Ref. 119465). There are fewer tooth rows, 2-5, on both upper and lower jaws in T. biriwira than in other species of Tropheops, 6-8, except in T. kumwera and T. kamtambo; Tropheops biriwira can be distinguished from T. kumwera and T. kamtambo by an on avreage larger eye, horizontal eye diameter 30.8-40.4% of head length and vertical eye diameter 29.6-35.4% of head length vs. 25.8-32.6% and 24.0-31.4% in T. kumwera and T. kamtambo, and also on average shorter snout, snout length 26.5-37.8% of head length vs. 28.0-42.8% in T. kumwera (Ref. 119465).
Description: Elongate species, body depth 26.8-32.1% of standard length, with greatest body depth at base of fourth or fifth dorsal-fin spine (Ref. 119465). Dorsal body profile with gradual downward curve to soft-rayed portion of dorsal fin then more acute curve to posterior origin of dorsal fin, gradual taper to caudal fin; ventral body profile between pelvic and anal fin flat with upward curve from anterior point of anal fin to caudal fin; head profile straight to slightly convex between snout tip and interorbital area; snout with 80-90° angle with body axis; dorsal head profile round to dorsal-fin origin (Ref. 119465). Teeth in outer rows bicuspid anteriorly and unicuspid posteriorly; all inner rows have tricuspid teeth medially and unicuspid laterally, with greatly enlarged conical teeth on lateral part of upper jaw (Ref. 119465). First dorsal-fin spine about one fourth length of last spine; soft dorsal fin with subacuminate tip, fourth ray longest, reaching to 1/3 of caudal fin in both males and females; pectoral fin rounded, paddle-shaped; fourth ray longest, length reaching to 1/3 of caudal fin in both males and females; caudal fin subtruncate to emarginate; pelvic fin not to anal fin in female; length in male to first anal-fin rays (Ref. 119465). Flank scales large, ctenoid; abrupt difference to small cycloid scales on breast and belly; cheek with 4-5 rows of small scales; tiny scales from base to 3/4 length of caudal fin (Ref. 119465).
Colouration: Males in territorial colour with greenish-blue ground colouration and 5-6 distinct brown bars; caudal peduncle greenish-brown; head brown with 1 light blue interorbital bar and green highlights; anal fin greenish-brown with 4-6 yellow ocelli; green marginal band; pectoral-fin rays brown with clear membranes (Ref. 119465). Females with light brown ground colouration and 4-5 faint lateral dark brown bars; belly and breast beige/brown; head with light brown colouration and 1-2 faint greenish/beige/brown interorbital bars; dark brown opercle spot with green higlights; pectoral fin and pelvic fin brown with light blue margin bands (Ref. 119465). |