Platystomatidae are considered monophyletic from a morphological (McAlpine 1989 and Korneyev 1999) and molecular (Han and Ro 2005) perspective, but the lineage is weakly supported by the Minimum Evolution tree, and there are indications that Platystomatidae may be a paraphyletic group basal to the Ulidiidae.
The diagnostic characters (synapomorphies) common to all Platystomatidae, that separate them from these families are listed below (the most significant in bold typeface).
Adult Platystomatidae are frequently confused with other higher Tephritoidea: Tephritidae (or fruit flies), the Ulidiidae (picture-winged flies), the Pyrgotidae (waved light flies) and the Richardiidae. They can be sorted from these families using the key characters described below.
The presence of setae along the entire length of wing vein R1, frequently vein R4+5 and sometimes the basal portion of vein M4, where it is adjacent to cells bm and cua