Key to species of Trathala in Madagascar

1 Tergite II twice longer than tergite I, propodeal carination strongly reduced, ovipositor tip strongly sinuate (Fig. 12 e).................................................................... T. lachaisae Rousse, Villemant et Seyrig sp. nov.

- Tergite II less than twice longer than tergite I, propodeal carination distinct........................................ 2

2(1) Flagellum with a median pale ring (Fig. 12 c)........................................... T. annulicornis (Tosquinet)

- Flagellum without median pale ring....................................................................... 3

3(2) Clypeus narrow (Ci <1.6) and strongly convex, face flat (Fig. 12b)........ T. agnielae Rousse, Villemant et Seyrig sp. nov.

- Clypeus wider and flatter............................................................................... 4

4(3) Face and clypeus black with orbits yellow (Fig. 12 d).................... T. mimouna Rousse, Villemant et Seyrig sp. nov.

- Face and clypeus yellow to light reddish taestaceous without any black marking................................... 5

5(3) Postpectal carina ventrally swollen in front of middle coxae and medially fainter, scutellum reddish, metasoma black............................................................... T. orchestotrichias Rousse, Villemant et Seyrig sp. nov.

- Postpectal carina not swollen, scutellum yellow, metasoma yellow with tergites I–II black....... T. flavoorbitalis (Cameron)