Leiocassis, Bleeker, 1857

Ng, Heok Hee & Hadiaty, Renny K., 2019, Leiocassis rudicula (Teleostei: Siluriformes: Bagridae), a new catfish from eastern Borneo, Zootaxa 4651 (1), pp. 191-200 : 197-198

Key to the species of Leiocassis (modified from Ng & Tan, 2018)

1. Posterior tip of supraoccipital process in contact with nuchal plate; anal fin with broad brown band covering at least middle third................................................................................................ 2

- Posterior tip of supraoccipital process not in contact with nuchal plate; anal fin with irregular narrow brown band covering less than middle third...................................................................................... 3

2. Length of adipose-fin base 16–17% SL; dorsal-spine length 21% SL; pectoral-spine length 18–19% SL [Sumatra: Alas River drainage].................................................................................... L. aculeata

- Length of adipose-fin base 13–15% SL; dorsal-spine length 16–18% SL; pectoral-spine length 15–18% SL [Malay Peninsula: Mae Nam Kolok drainage southwards to Endau River drainage; Sumatra: Wampu River drainage southwards to Musi River drainage; Java: Ciberang River drainage; Borneo: Kapuas River drainage]............................. L. poeciloptera

3. Body uniform medium brown, without cream or yellow irregular bands or patches; pectoral-spine length 9–13% SL [Borneo: Kayan River drainage]........................................................................ L. tenebrica

- Body mottled brown, with cream or yellow irregular bands or horizontally elongate patches; pectoral-spine length 13–21% SL................................................................................................. 4 4. Posterior margin of dorsal spine smooth................................................................... 5

- Posterior margin of dorsal spine with 5–22 serrae............................................................ 6

5. Horizontally elongate cream or yellow patches on sides of body between dorsal and adipose fins; outermost principal caudal-fin rays with short extensions; body depth at anus 11–16% SL; caudal peduncle depth 6–7% SL [Borneo: Mentaya, Sebangau and Kahayan river drainages; Sumatra: Lalang and Batang Hari river drainages]............................... L. bekantan

- Irregular cream or yellow band on sides of body between dorsal and adipose fins; outermost principal caudal-fin rays without extensions; body depth at anus 16–20% SL; caudal peduncle depth 9–11% SL [Borneo: Mahakam River drainage].......................................................................................... L. rudicula new species

6. Length of adipose-fin base 19–22% SL; head length 26–29% SL [Borneo: Kalabakan and Segama river drainages]. L. collina

- Length of adipose-fin base 14–18% SL; head length 29–34% SL [Bangka: Baturusa River drainage; Belitung: Cerucuk River drainage; Borneo: Kapuas River drainage eastwards and northwards to Padas River drainage, Barito River drainage]............................................................................................... L. micropogon