The fly species crassipes de Meijere is transferred from the Sphaeroceridae to the Drosophilidae since Platyborborus de Meijere, a monotypic genus, is a junior synonym of Colocasiomyia de Meijere. Colocasiomyia crassipes is a very highly modified member of the genus due to its flattened body, reduction and loss of many groundplan setae, deep antennal fossae, and crassate hind legs. The holotype and only known specimen, from Java, is redescribed in detail and illustrated. New records of Colocasiomyia stamenicola (Carson & Okada) and C. gigantea (Okada) are reported from Guadalcanal, Solomon Islands, considerably outside their reported ranges. Colocasiomyia nepalensis sp. n. is described from Kathmandu, Nepal. Cladistic relationships in the genus are briefly examined and related to biogeography and aroid host use.