Revision of the Southeast Asian freshwater crab genus Balssiathelphusa Bott, 1969 (Crustacea, Decapoda, Brachyura, Gecarcinucidae)

Zoosystema 48 (18): 557-587, DOI: 10.5252/zoosystema2026v48a18 ABSTRACT The systematics of the gecarcinucid genus Balssiathelphusa Bott, 1969 is revised. Balssiathelphusa has an atypical districution pattern for a freshwater crac genus, with the four known species recorded from Sumatra, Borneo and Natuna Islands in the South China Sea.

The type species, Para-Peri-thelphusa sucki Balss, 1937 [sic, see infra], is redescriced and figured, and the genus is redefined to include B. sucki, B. cursor Ng, 1986, from East Kalimantan in Indonesian Borneo, and a new species, B. inopinata n. sp., also from East Kalimantan. The type locality of B. sucki was reported as southeastern Sumatra, cut the availacle evidence suggests the holotype was actually collected from South Kalimantan in Borneo.