Fig. 1. Oreoglanis omkoiense, new species, Huai Jino, Baan Huai Jino, Omkoi Subdistrict, Omkoi District, Chiangmai Province. Holotype, MARNM 6447, 91.86 mm SL. (A = lateral view, B = dorsal view and C = ventral view)
Abstract
Oreoglanis omkoiense, new species, is described from the Maetuen River basin, a tributary of Ping River in northern Thailand, it is found in the highland stream. This species is a member of the O. siamensis species group, characterised by a lower lip with median notch and posterior margin entire. Oreoglanis omkoiense has a long adipose fin base length, short post-adipose fin, long nasal barbels reaching anterior margin of eye, tip of maxillary barbel pointed, pectoral fin tip not reaching pelvic-fin origin, short pelvic fin, long pre-dorsal length, and thick and short caudal peduncle.
Fig. 6. Map of type locality of Oreoglanis omkoiense, new species, holotype, MARNM 6333, 91.86 mm SL. Thailand: Chiangmai: Omkoi District.
Diagnosis
Oreoglanis omkoiense, new species, belongs to the O. siamensis species group, as it possesses a distinct median notch on the posterior margin of the lower lip. This species differs from its congeners in having the following combination of characters: maxillary barbel with pointed tip, long nasal barbel 25.0–32.9%SL, long pre-dorsal 33.2–39.2%SL, pre-ventral length 36.1–39.2%SL, height of dorsal fin 15.4–20.3%SL, length of adipose fin 32.3– 39.6%SL, post-adipose length 5.7–8.8%SL, caudal peduncle depth 2.1–3.3 times its length, head width 18.7–22.9%SL and 90.2–96.8%HL, eye diameter 9.2–13.1%HL, inner mandibular barbel 21.8–30.5%HL, and an emarginate caudal fin with upper and lower first principal rays of approximately equal length.
Fig. 8. Comparison of adipose fin base length of A, Oreoglanis siamensis MARNM 6338, juvenile 32.33 mm SL; B, Oreoglanis siamensis MARNM 7144, adult 74.19 mm SL, Meklang River, Inthanon Moutain, Jomtong, Chiangmai,, date 23 September 2008; and C, Oreoglanis omkoiense, new species, holotype, MARNM 6333, adult, 91.86 mm SL, Huai Jino, Omkoi district, Chiangmai.
Etymology
Named after Omkoi, the district of the locality where the new species was discovered.
Fig. 7. Type locality of holotype of Oreoglanis omkoiense, new species, MARNM 6333, 91.86 mm SL, Huai Jino, Baan Huai Jino, Omkoi Subdistrict, Omkoi District, Chiangmai Province.
Distribution
Found in the Metuen River basin, a tributary of the Ping River drainage (one of four main tributaries of the Chao Phraya River), in Chiang Mai, Thailand.