| Diagnosis: |
Dorsal spines (total): 0-0; Dorsal soft rays (total): 12-12; Anal spines: 0-0; Anal soft rays: 16-17; Vertebrae: 40-41. Diagnosis: Within the Congo basin, Raiamas marqueti can be distinguished from R. batesii, R. kheeli and R. moorii by a lower number of lateral line scales, 45-48 vs. 68-70, 65-68 and 54-61 respectively; from R. longirostris by a greater head width, 37-45% of head length vs. 31%, and a deeper body, 18.8-23.3% of standard length vs. 16.5%; from R. buchholzi and R. christyi by the absence of a large dark spot at the base of the caudal fin vs. presence, a longer dorsal-fin base, 12.5-14.0% of standard length vs. 10.1-12.0% and 10.4-11.6% respectively, and a shallower head depth, 49.5-55.9% of standard length vs. 56.5-61.8% (Ref. 122357). Furthermore, it is distinguished from the phenotypically similar species R. intermedius and R. brachyrhabdotos by a shallower body, 18.8-23.3% of standard length vs. 25.2-28.8% and 23.6-29.8% respectively, and a more or less horizontal predorsal profile vs. convex predorsal profile; and from R. salmolucius by a shorter head, 27.0-30.1% of standard length vs. 30.2-33.6%, and the short distance between nostril and eye, 6-7% of head length vs. 5-6%, overlap due to negative allometry, and the narrower width of the first two bars posterior to the pectoral fin covering only 1.5-2.0 lateral line scales vs. wide bars covering 2.5-3.0 lateral line scales (Ref. 122357). Outside the Congo basin, Raiamas marqueti is distinguished from all other species, except R. ansorgii, R. nigeriensis and R. senegalensis, by a intermediate high number of lateral line scales, 45-48 vs. 36-38 in R. levequei, 58-63 in R. scarciensis and 39-42 in R. steindachneri; from R. ansorgii by the insertion of the dorsal fin slightly behind the pelvic-fin insertion, about three or four lateral line scales between the verticals through the anterior base of the dorsal fin and the pelvic-fin insertion vs. six or seven scales; from R. nigeriensis by a longer head, 27.0-30.1% of standard length vs. 18.6-25.0%, and a shorter eye diameter, 20-26% of head length vs. 29-36%; and from R. senegalensis by a higher number of branched dorsal-fin rays, 9 vs. 8 (Ref. 122357).
Description: Body elongated; greatest body depth at anterior dorsal-fin region; predorsal body profile almost straight (Ref. 122357). Head with slightly convex upper profile; snout pointed, slightly projecting beyond anterior margin of lower jaw; with mouth closed, distal tip of maxilla not reaching to posterior orbital margin; fourth infraorbital bone somewhat smaller than third infraorbital bone and extending well behind posterior border of the latter (Ref. 122357). Dorsal fin on posterior half of body, originating behind level of pelvic-fin origin; its posteriormost ray distinctly behind anal-fin origin; about 3-4 lateral line scales between verticals through dorsal-fin origin and pelvic-fin insertion; pectoral axial scale with pointed border and extending about half the length of leading edge of pectoral fin; pectoral and pelvic fins set low on body in a sub-horizontal plane, their bases oblique; pelvic axial scale pointed, variously elongate, measuring 45-85% of pelvic-fin length; anal fin falciform, last ray about 29-35% of longest anterior ray and originating below level of last third of dorsal-fin base; posterior tip of pelvic fin not reaching anus; caudal fin deeply forked, median rays about 31-35% of outer longest rays, lobes of similar size, pointed and triangular; dorsal fin with 3 unbranched and 9 branched rays, anal fin with 3 unbranched and 13-14 branched rays, pectoral fin with 1 unbranched and 15-16 branched rays, and pelvic fin with 1 unbranched and 8 branched rays (Ref. 122357). Scales bordering caudal-fin base smaller than body scales; 45-48 lateral line scales, 8-9 scales between lateral line and dorsal-fin origin, 3 scales between lateral line and pelvic-fin origin, 20-23 scales in predorsal rows, 14-15 circumpeduncular scales (Ref. 122357).
Colouration: In life, overall background colouration of body silvery with yellowish he, being more greenish-grey above and silvery below lateral line; anterior half of iris orange, posterior half white; body with seven to eleven vertical black bars, each covering 2-3 lateral line scales; number of vertical bars varying from one side to other, but the difference between both sides never exceeding one single bar; anterior bars slightly longer than posterior ones, with first two bars extending below lateral line; two last bars situated on caudal peduncle and nearly as high as wide; space between first 4-5 vertical bars can be twice the width of such bars in specimens measuring less than about 100 mm standard length and becomes approximately comparable to width of bar in larger specimens; snout and dorsum of head metallic greenish; fins yellowish at their base and silvery, translucent distally; dorsal fin with black marginal band; unbranched rays of dorsal fin also black (Ref. 122357). In preserved specimens, only black colouring of bars persists, all yellowish colour on body as well as orange colour of iris fades and ultimately disappears; in addition, snout and dorsum of head become black (Ref. 122357). |
