Fruit flies in Bactrocera tau complex are important pests, but their morphological taxonomy is still unsettled. In this paper, specimens from gac fruits (Momordica cochinchinensis) are attempted to classify by geometric morphometric and genetic analyses. Geometric morphometric study of wing venation and aculeus shape among samples suggested a new species in this taxon. Sequences in the cytochrome oxidase I region were compared with reference material in this complex, as well as other taxa within the same subgenus. Phylogenetic analysis based on COI revealed a new species of the B. tau complex, B. tau form J. Therefore, the criteria of body color patterns proved to be taxonomically valid for species classification and identification in this species complex.