The identities of two poorly known species of Indo-West Pacific sesarmid crabs, which have been referred to the genus Chiromantes Gistel, 1848, are clarified. Sesarma obesum Dana, 1851, is shown to be a senior synonym of Metasesarma rousseauxi H. Milne Edwards, 1853. A neotype from northern Borneo is designated to fix the identity of the species. Sesarma eydouxi H. Milne Edwards, 1853, a species supposedly described from Vietnam and not reported there or in the region since its description, is shown to be a junior synonym of the Atlantic species Sesarma rectum Randall, 1840; its original provenance almost certainly being incorrect.
Crustacea, Decapoda, Brachyura, Sesarmidae, Sesarma obesum, Sesarma eydouxi.