Rasbora dusonensis

Rasbora dusonensis (Bleeker 1850)

Rasbora dusonensis (Bleeker 1850) Rasbora dusonensis: Authors' data (Gerik; Sg. Bidor).

Provisional checklist of freshwater fish diversity and distribution in Perak, Malaysia, and some latest taxonomic concerns

discussion

Remarks. Rasbora dusonenesis (Bleeker, 1850 b), herein treated as a new record for Brunei even though it may have been partially recorded as Rasbora cf. tornieri by Parenti & Meisner, 2003: 43 (Belait basin). Rasbora dusonensis is easily distinguished from Rasbora tornieri by its yellow caudal fin with a broad black distal margin. Rasbora tornieri has reddish caudal fin with a narrow blackish distal margin. Both species often occur sympatrically (Ng & Kottelat, 2013 a: 63).

Annotated checklist of freshwater fishes from Brunei Darussalam, Borneo

description

Description. Morphometric data are given in Table 1 and meristic data in Table 2. Body slender, elongate, laterally compressed, its greatest depth between pelvic-fin insertion and dorsal-fin origin. Dorsal profile of head sloping evenly from margin of upper lip to supraoccipital. Snout acutely rounded. Dorsal profile of body slightly convex from supraoccipital to dorsal-fin origin, thereafter slightly concave to caudal-fin base. Ventral profile gently convex from margin of lower lip to pelvic-fin origin, with slight concavity at isthmus; almost horizontal between pelvic- and anal-fin origins, gently concave at caudal peduncle. Mouth oblique, superior. Symphyseal knob on dentary strongly developed, fitting into corresponding indentation between premaxillae. Scales cycloid. Lateral line complete (all scales perforated; 29 – 30 + 2), its anterior portion curving ventrally. Dorsal fin pointed at tip, with slightly convex posterior margin. Dorsal-fin origin posterior to vertical through base of last pelvic-fin ray. Dorsohypural distance equal to or slightly less than distance between dorsal-fin origin and posterior orbital margin. Pectoral-fin subtriangular, with subrectangular axillary

The identity of the cyprinid fishes Rasbora dusonensis and R. tornieri (Teleostei: Cyprinidae)

diagnosis

Diagnosis. Rasbora dusonensis and R. tornieri are distinguished from congeners in having a broad, darkbrown sharply-defined midlateral stripe on body extending from opercle to caudal-fin base and separated from the dark-brown supralateral stripe and dorsum by a highly contrasting light longitudinal area. The following characters (none unique) also help in identifying them: 12 – 14 predorsal scales; dorsohypural distance equal to or slightly less than distance between dorsal-fin origin and posterior orbital margin; 14 circumpeduncular scales; and a brightly coloured caudal fin in life. Rasbora dusonensis differs from R. tornieri in having a bright yellow caudal fin with a broad black posterior margin (vs. carmine red without or with a very narrow black posterior margin), and a more slender caudal peduncle (8.5 – 9.6 times in SL vs. 7.9 – 8.8; 10.4 – 11.7 % SL vs. 11.4 – 12.7).

The identity of the cyprinid fishes Rasbora dusonensis and R. tornieri (Teleostei: Cyprinidae)