Geosesarma wongi sp. nov., a distinctive new species of semiterrestrial crab from Tapah Hills in Perak, Peninsular Malaysia; with notes on G. peraccae (Nobili, 1903) and G. cataracta Ng, 1986 (Crustacea, Brachyura, Sesarmidae)

A new species of semiterrestrial freshwater crab is described from Tapah Hills in Peninsular Malaysia. Geosesarma wongi sp. nov. is the 13(th) member of the genus reported from the country and is most similar to G. peraccae (Nobili, 1903) and G. cataracta Ng, 1986, but easily separated by its distinct carapace features and structures of the adult male chela and male first gonopod. The types of G. peraccae are figured for the first time. Geosesarma cataracta is also figured in detail, and the type series is shown to be mixed.