On the identities of the highland vampire crabs, Geosesarma foxi (Kemp, 1918) and G. serenei Ng, 1986, with description of a new phytotelmic species from Penang, Peninsular Malaysia (Crustacea: Decapoda: Brachyura: Sesarmidae)

The identities of two poorly known semiterrestrial sesarmid crabs Geosesarma foxi (Kemp, 1918) and G. serenei Ng, 1986, from northern Peninsular Malaysia are clarified with the study of additional material. A new species associated with phytotelms in Penang, G. faustum n. sp., is described and distinguished from the two known species by various carapace, male pleon and gonopod characters. The taxonomy of the three speciesis discussed. All three are highland species, occurring only at altitudes higher than 700 m; and are characterisedby their quadrate carapace, long and slender ambulatory legs, absence of a flagellum on the exopod of their third maxilliped, and relatively slender male first gonopod.