Description of a new genus and new species of freshwater crab (Brachyura: Potamoidea) from southern Vietnam

Abstract

A new genus and new species of potamid freshwater crab, Xestomon tacu, is described from Ta Kou mountain in southern Vietnam. The new genus is characterised by its transversely ovate and smooth carapace surface, the very low to undiscernible epigastric and postorbital cristae, complete absence of a flagellum on the third maxilliped, relatively short ambulatory legs, a male telson which is acutely triangular with the lateral margins distinctly concave, and a short stout male first gonopod which has the terminal segment gently curved upwards.