The fiddler crab, Uca splendida (Stimpson, 1858) has been synonymized under Uca crassipes (White, 1847) since Crane (1975). Studies of specimens from the Hong Kong type locality and adjacent areas of China, Taiwan and Vietnam show that U. splendida is a valid species, with a characteristic suite of carapace and gonopod features as well as a distinct cytochrome oxidase I (COI) signature. Genetic work shows that U. splendida belongs to a well-supported clade and is the sister species of U. crassipes. The distribution of U. splendida is restricted to continental East and continental Southeast Asia, in contrast to the oceanic distribution of U. crassipes. Both species, however, are sympatric in Penghu Islands, western Taiwan and Dongsha Island (=Pratas Island).