Abstract
Tmethypocoelis Koelbel, 1897, is a central Indo-West Pacific genus of small intertidal, soft sediment dotillid crabs that includes five recognised species. Two new species, Tmethypocoelissimplexsp. nov. and T.celebensissp. nov., are here described from Sulawesi, Indonesia. Tmethypocoelissimplexsp. nov. is found on the west coast of Central Sulawesi, while T.celebensissp. nov. occurs in the north-eastern part of Sulawesi. Both new species differ from each other and known congeners by the male cheliped, male pleon, and male first gonopod characters. The differences in gastric mill morphology further confirm the two species as new. The distinct water current patterns in the Makassar Strait and the Maluku Channel might have contributed to the evolution of these two sibling species.