The monophyly of this distinctive family has never been questioned, however it is here further established by the following suite of apomorphic characters (plesiomorphic states in parentheses): (1) frontal-orbital bristle absent (present); (2) inner vertical bristle absent (present); (3) arista bipectinate (short-pubescent); (4) ocellar triangle differentiated (absent); (5) postpronotum not delimited from mesoscutum posteromedially (delimited by suture); (6) precoxal bridge present (absent); (7) posterior notopleural bristle small and hair-like (large and bristle-like); (8) supra-alar bristle absent (present); (9) subscutellum transverse, virtually absent (moderately developed); (10) prespiracular processes present (absent); (11) laterotergite flat (convex); (12) metasternum fused posteromedially with postcoxal bridge (metasternum separate from postcoxal bridge posteromedially); (13) alula absent (present); (14) spiracle of first abdominal segment in tergite (in membrane); (15) tergites 2 and 3 fused (separate); (16) hypandrial arms with large, setulose ventral lobe (lobe very small (Centrioncus) or absent); (17) proximal opening of basiphallus greatly enlarged, its dorsal margin articulated with hypandrial bridge (proximal opening small, dorsal margin not articulated with hypandrium); (18) four spermathecae (three or two).

Characters 5, 12, 16 and 17 were not previously recognised as synapomorphies of the family. Some characters appear convergently in other Diopsoidea as follows: (1): Diopsidae excluding Centrioncus, Megamerina, Gobryidae, some Psilidae; (2): Centrioncus; (3): Gobryidae, Nothybidae; (4): Psilidae; (6): many Diopsidae excluding Centrioncus, Gobryidae, Nothybidae; (8): most Diopsidae excluding Centrioncus; (9): most Psilidae; (13): Diopsinae, Gobryidae, Nothybidae; (15): some Diopsinae; (18): Cladodiopsis (Diopsidae).