Evidence of the earliest fossil freshwater decapod of Southeast Asia (Crustacea: Decapoda: Brachyura)

We report the fi rst evidence for Miocene brachyuran freshwater crabs from Southeast Asia, a hotspot of extant freshwater crab biodiversity. This confi rms the presence of potamoid freshwater crabs in Southeast Asia during the Miocene, as suggested by previous molecular clock estimates. The specimen (one claw fragment) originates from the Middle to Late Miocene site of Vieng Phouka, Lao People’s Democratic Republic. Sedimentological and palaeontological data indicate the former existence of alternating swampy and lacustrine environments, inhabited by the crab and a low-diversity gastropod fauna.