Two tribes hidden in one genus: the case of Agaedioxenis Villeneuve (Diptera: Tachinidae: Exoristinae)

The Afrotropical tachinid “genus” Agaedioxenis Villeneuve is taken here as an example of the challenges faced by dipterists in classifying one of the most diverse and species rich families of organisms on Earth. Our study has revealed “two tribes hidden in one genus”, with one lineage representing a genus belonging to the tribe Goniini (Agaedioxenis) and the other representing a genus belonging to Eryciini (Eugaedioxenis gen. nov.). The two genera have been revised through an integrative approach of morphology and genetics (COI barcode sequences). The genus name Agaedioxenis replaces that of Gaedioxenis Townsend as a valid genus name. Agaedioxenis is recognized from five species consisting of two previously described species (Agaedioxenis setifrons (Villeneuve) and Agaedioxenis brevicornis (Villeneuve) both comb. nov.) and three new species (Agaedioxenis kirkspriggsi sp. nov., Agaedioxenis succulentus sp. nov., and Agaedioxenis timidus sp. nov.). Agaedioxenis propinqua (Villeneuve) is recognized as a subjective synonym of A. brevicornis (Villeneuve), syn. nov., and by First Reviser action, the latter is chosen as the senior of the two names. Eugaedioxenis gen. nov. is recognized based on two species, Eugaedioxenis haematodes (Villeneuve), type species and comb. nov., and Eugaedioxenis horridus sp. nov. All new species of both genera are described from South Africa. We further discuss how genetics, morphology, and natural history have contributed to revise the generic circumscription of Agaedioxenis, bringing about both the description of Eugaedioxenis and the revision of the suprageneric classification for these two taxa.