Exostoma, Blyth, 1860

Luo, Zhaojun & Chen, Xiaoyong, 2020, Exostoma dulongensis a new glyptosternine catfish from the Irrawaddy basin Yunnan, China (Siluriformes: Sisoridae), Zootaxa 4802 (1), pp. 99-110 : 107-108

Key to Exostoma species

1 Adipose fin confluent with caudal fin..................................................................... 2 – Adipose fin separated from caudal fin..................................................................... 9 2 Pelvic fin reaching anus................................................................................ 3 – Pelvic fin not reaching anus............................................................................. 8 3 Parallel or rounded striae on anterolateral surface of lips...................................................... 4 – Parallel and rounded striae on anterolateral surface of lips........................................ E. gaoligongense 4 Parallel striae on anterolateral surface of lips................................................................ 5 – Rounded striae on anterolateral surface of lips............................................................... 6 5 Total vertebrae 42–43, caudal fin weakly forked..................................................... E. ericinum – Total vertebrae 39–41, caudal fin weakly emarginate................................................ E. chaudhurii 6 Outer mandibular barbel reaching or surpassing first pectoral fin base................................. E. vinciguerrae – Outer mandibular barbel reaching 2/3 of distance between its base of first pectoral fin ray............................ 7 7 Caudal fin weakly forked, caudal peduncle 9.2%–9.7% SL........................................... E. berdmorei – Caudal fin lunate, caudal peduncle 6.2%–8.5% SL................................................ E. peregrinator 8 Total vertebrae 40–43, caudal fin weakly forked, dorsal fin base length 6.4%–10.6% SL........... E. dulongensis sp. nov. – Total vertebrae 38–39, caudal fin lunate, dorsal fin base length 12.4%–13.5% SL.......................... E. sawmteai 9 Posterior tip of adipose without incision.................................................................. 10 – Posterior tip of adipose with incision..................................................................... 16 10 Pelvic fin reaching anus............................................................................... 11

– Pelvic fin not reaching anus............................................................................ 14

11 Parallel or rounded striae on anterolateral surface of lips......................................................12

– Parallel and rounded striae on anterolateral surface of lips............................................... E. kottelati

12 Rounded striae on anterolateral surface of lips.............................................................. 13

– Parallel striae on anterolateral surface of lips.................................................... E. tenuicaudata

13 11 branched pectoral fin rays, head length 22.6%–24.9% SL, head width 79.7%–88.2% HL........... E. mangdechhuensis

– 12–13 branched pectoral fin rays, head length 21.4% SL, head width 97.9% HL............................ E. labiatum

14 Dorsal profile slightly arched, post-dorsal profile gently sloping............................................... 15

– Dorsal profile greatly arched, post-dorsal profile severely sloping......................................... E. stuarti

15 Caudal fin lunate, depth at anus 10.4%–12.3% SL, caudal peduncle depth 6.7%–8.6% SL, caudal peduncle length 9.5%–11.1% SL.......................................................................................... E. tibetana

– Caudal fin emarginate, depth at anus 14.0%–16.5% SL, caudal peduncle depth 33.0%–43.0% SL, caudal peduncle length 44.0%–57.0% SL.......................................................................... .. E. barakensis

16 Nasal barbel reaching beyond posterior orbital margin, 19.0%–31.0% HL, caudal peduncle length 17.0%–20.5% SL..................................................................................................... E. sectile

– Nasal barbel not reaching posterior orbital margin, 34.0%–43.0% HL, caudal peduncle length 26.3%–28.0% SL....................................................................................................... E. effrenum