Abstract
Clarias serniosus, a new Southeast Asian walking-catfish species, is described from the Bolavens Plateau in southern Laos. The new species is a member of the C. batrachus species complex, and can be distinguished from congeners in the complex in having a combination of: occipital process length 15–17 % HL, head length 28.2–28.6% SL, head width 18.5–19.2% SL, head depth 13.0–13.7% SL, distance between the occipital process and the base of the first dorsal-fin ray 8.5% SL, smooth anterior edge of pectoral spine, 67 dorsal-fin rays, body depth at anus 16.2–16.5% SL, and 57 total vertebrae.