Oreoglanis, Smith, 1933

Suvarnaraksha, Apinun, 2020, Oreoglanis omkoiense: a new torrent catfish from northern Thailand (Pisces: Siluriformes, Sisoridae), Raffles Bulletin of Zoology 68, pp. 779-790 : 780

Key to the species of Oreoglanis

Adapted and modified from Ng & Kottelat, 1999; Ng & Freyhof, 2001; Ng & Rainboth, 2001; Ng, 2004; Chen et al., 2017; Kong et al., 2007; Vidthayanon et al., 2009; Linthoingambi & Vishwanath, 2011; Sinha & Tamang, 2015; Chen et al., 2017. Note: CP = Chao Phraya River basin, MK = Mekong River basin, SW = Salween River basin, ID = Irrawaddy River basin, BP = Brahmaputra River basin, SL = Song Lam River basin.

1. Lower lip notched medially, with entire or weakly laciniate posterior margin; emarginate caudal-fin.................................2

– Lower lip lacking a median notch, with prominent projections along posterior margin; laciniate caudal-fin with principal caudal rays extended.........................................................................16

2. Pectoral-fin not reaching to pelvic-fin origin .........................3

– Pectoral-fin reaching or surpassing pelvic-fin origin .............5

3. Head width 90.2–96.8%HL, post-adipose distance 5.7–8.8%SL and dorsal-fin high 15.4–20.3%SL ................ O. sudarai (CP)

– Head width 79.3–87.4%HL, post-adipose distance 8.4–14.3%SL and dorsal-fin high 11.4–14.4%SL .........................................4

4. Caudal peduncle length and caudal peduncle depth ratio 4.9–8.4, adipose-fin base 29.1–36.7%SL and head 15.3–17.7%SL....... ..................................................................... O. siamensis (CP)

– Caudal peduncle length and caudal peduncle depth ratio 2.1–3.3, adipose-fin base 35.6–39.5%SL and head 18.7–22.9%SL....... ............................................. O. omkoiense , new species (CP)

5. Branched anal-fin rays 2 ...................... O. heteropogon (SW)

– Branched anal-fin rays 3–6. ....................................................6

6. Caudal-fin lunate .....................................................................7

– Caudal-fin emarginate .............................................................8

7. Adipose-fin base length 24.2–29.7%SL, dorsal-fin base length 6.6–9.2%SL, anal-fin base length 2.5–3.6%SL........................ ............................................................. O. jingdongensis (MK)

– Adipose-fin base length 30.7–38.1%SL, dorsal-fin base length 10.9–13.7%SL, anal-fin base length 5.6–7.6%SL.................... .................................................................. O. suraswadii (MK)

8. Caudal-fin rays 5+5.............................. O. hponkangensis (ID)

– Caudal-fin rays 6+6 or 7+8 or 8+7 ........................................9

9. Posterior margin of maxillary barbel with laciniate projections. ..................................................... O. setiger (MK)

– Posterior margin of maxillary barbel without or with lobulated projections .............................................................................10

10. Caudal peduncle depth 8.0–8.7%SL....... O. macropterus (ID)

– Caudal peduncle depth 3.0–6.3%SL.....................................11

11. Small eye 7.7–8.8%HL ................................... O. insignis (ID)

– Larger eye 9.0–13.7%HL......................................................12

12. Branched anal-fin rays 3 .......................................................13

– Branched anal-fin rays 4–6 ...................................................14

13. Post adipose-fin length 6.5–9.0%SL..... O. immaculatus (SW)

– Post adipose-fin length 9.9–10.8%SL....... O. majusculus (BP)

14. Dorsal to adipose-fin distance 21.1%SL .................................. ................................................................. O. pangenensis (BP)

– Dorsal to adipose-fin distance 14.4–16.0%SL ......................... ................................................................... O. laciniosus (SW)

15. Maxillary barbel tip pointed ........................... O. colurus (CP)

– Maxillary barbel tip rounded ................................................16

16. Branched dorsal-fin rays 7 .................... O. macronemus (MK)

– Branched dorsal-fin rays 5–6 ................................................17

17. Post adipose distance short 2.8–7.0%SL..............................18

– Post adipose distance short more than 7.0%SL ...................19

18. Emarginate caudal-fin shape ..................... O. tenuicauda (CP)

– Lunate caudal-fin shape .................................. O. vicinus (CP)

19. Branched caudal-fin rays 7+7 ...............................................20

– Branched caudal-fin rays 5–6+6–7, 7–6...............................22

20. Long pre-dorsal length 36.1–37.1%SL........ O. lepturus (MK)

– Pre-dorsal length short 30.8–36.5%SL .................................21

21. Anal-fin base length 2.7–3.6%SL, caudal peduncle length 18.7–21.7%SL, head width 18.9–22.4 %SL ............................ .................................................................... O. hypsiurus (MK)

– Anal-fin base length 3.6–4.9%SL, caudal peduncle length 21.5–24.0 %SL, head width 16.4–20.8%SL ............................ .................................................................... O. delacouri (MK)

22. Post-adipose distance 9.0–13.8%SL, head depth 9.3–13.5%SL and pre-pelvic length 38.9–44.0%SL .... O. nakasathiani (CP)

– Post-adipose distance 6.8–8.9%SL, head depth 7.3–8.0%SL and pre-pelvic length 33.1–9.4%SL .....................................23

23. Branched dorsal-fin rays 6, small eye 7.5–9.8%HL, adipose-fin base length 36.7–47.8%SL, pectoral-fin length 23.0–24.4%SL and head length 18.8–20.7%SL ................... O. frenatus (MK)

– Branched dorsal-fin rays 5, small eye 10.5–12.1%HL, adipose-fin base length 31.7–36.0%SL, pectoral-fin length 25.3–26.4%SL and head length 21.4–24.7%SL....................... ....................................................................... O. infulatus (SL)