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| Oreoglanis omkoiense Suvarnaraksha, 2020 |
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.
Key words. Omkoi, Metuen River, conservation, fish diversity, Southeast Asia
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| 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) |
Oreoglanis omkoiense, new species
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.
Etymology. Named after Omkoi, the district of the locality
where the new species was discovered.
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.
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| Fig. 6. Map of type locality of Oreoglanis omkoiense, new species, holotype, MARNM 6333, 91.86 mm SL. Thailand: Chiangmai: Omkoi District. |
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| 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. |
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| 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. |
Apinun Suvarnaraksha. 2020. Oreoglanis omkoiense: A New Torrent Catfish from northern Thailand (Pisces: Siluriformes, Sisoridae). RAFFLES BULLETIN OF ZOOLOGY. 68: 779–790.
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