Raiamas brachyrhabdotos Katemo Manda, Snoeks, Chocha Manda & Vreven, 2018
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Family:  Danionidae (Danios), subfamily: Chedrinae
Max. size:  17.9 cm SL (male/unsexed)
Environment:  benthopelagic; freshwater,
Distribution:  Africa: Sankuru and Lulua rivers, both tributaries of Kasai River, and also Kwilu River, Congo River basin, in Democratic Republic of the Congo (Ref. 122357).
Diagnosis:  Dorsal spines (total): 0-0; Dorsal soft rays (total): 11-12; Anal spines: 0-0; Anal soft rays: 16-17; Vertebrae: 39-40. Diagnosis: Within the Congo basin, Raiamas brachyrhabdotos can be distinguished from R. batesii, R. kheeli and R. moorii by a lower number of lateral line scales, 44-46 vs. 68-70, 65-68 and 54-61 respectively; from R. longirostris by a shorter upper-jaw length, 46-52% of head length vs. 59%, and longer pre-anal length, 67.6-69.8% of standard length vs. 73.0%; 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, 13.3-14.7% of standard length vs. 10.1-12.0% and 10.4-11.6% respectively, and a longer anal-fin length, 18.4-22.5% of standard length vs. 15.2-17.6% and 13.8-16.5% respectively; from R. salmolucius by a shorter head, 28.5-29.5% of standard length vs. 30.2-33.6%, and a shorter pre-anal length, 67.6-69.1% of standard length vs. 69.9-72.9%; and from R. marqueti by a greater body depth, 23.6-29.8% of standard length vs. 18.8-23.3%, a convex predorsal profile vs. more or less horizontal; furthermore, it can be distinguished from R. marqueti and R. salmolucius by short and thin predorsal bars, not extending below the lateral line and usually covering 1-2 rows of lateral line scales, vs. wide and long bars, extending below the lateral line and covering more than 2 rows of the lateral line scales; from R. intermedius by a longer predorsal length, 59.9-61.7% of standard length vs. 57.2-59.2%, and deeper head, 56-60% of head length vs. 46-56% (Ref. 122357). Outside the Congo basin, Raiamas brachyrhabdotos is distinguished from all other species, except R. ansorgii, R. nigeriensis and R. senegalensis by an intermediate number of lateral line scales, 44-46 vs. 36-38 in R. levequei, 58-63 in R. scarciensis and 39-42 in R. steindachneri; from R. ansorgii by the dorsal fin inserted slightly behind the insertion of pelvic-fin origin, i.e. about two or three lateral line scales between the verticals through the anterior base of dorsal fin and the pelvic-fin insertion vs. dorsal fin inserted well behind pectoral-fin origin, i.e. by about six lateral line scales, and the fourth infraorbital extends markedly backwards when compared to the posterior border of the third infraorbital vs. slightly behind; from R. nigeriensis by a longer head, 28.5-29.5% of standard length vs. 18.6-25.0%; 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 rather convex (Ref. 122357). Head with slightly convex upper profile; snout pointed, slightly projecting beyond 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 originating on posterior half of body and posterior to level of pelvic fin insertion; about 2-3 lateral line scales between verticals through dorsal-fin origin and pelvic-fin insertion; base of last dorsal-fin ray distinctly behind anal-fin origin; pectoral and pelvic fins set low on body in a sub-horizontal plane, their bases oblique; pectoral axial scale pointed and extended about half the length of leading edge of pectoral fin; pelvic axial scale pointed and extended about half the length of leading edge of pelvic fin; anal fin falciform, last ray about one third of longest anterior ray and originating below last third of dorsal-fin base; caudal fin deeply forked, lower lobe longer than upper, median rays about one third of outer longest rays; dorsal fin with 3 unbranched and 8-9 branched rays, anal fin with 3 unbranched and 13-14 branched rays, pectoral fin with 1 unbranched and 15 branched rays, pelvic fin with 1 unbranched and 8 branched rays (Ref. 122357). Scales bordering caudal-fin base smaller than body scales; 44-46 lateral-line scales, 8-9 scales between lateral line and dorsal-fin origin, 2-3 scales between lateral line and pelvic-fin origin; 20-21 predorsal rows; 14 circumpeduncular scales (Ref. 122357). Colouration: Colour pattern in life unknown (Ref. 122357). In preserved specimens, overall body colour uniformly yellowish or brownish, lighter on belly; a total of seven to nine black-grey vertical bars on flanks, each covering the width of 1-2 lateral line scales; bars always above lateral line; number of bars varying from one side to other, but difference between both sides never exceeding one single bar; all specimens with one or two bars below dorsal fin and four post-dorsal bars; two or three predorsal bars; last two bars on caudal peduncle more or less rounded and overlapping lateral line; dorsal and caudal fins with marginal black band (Ref. 122357).
Biology: 
IUCN Red List Status: Not Evaluated (N.E.) Ref. (124695)
Threat to humans:  harmless
Country info:   
 

Entered by: Boden, Gert - 03.07.20
Modified by: Boden, Gert - 03.07.20

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