Systematics of coccophagine aphelinids

The family Aphelinidae is a diverse group of minute chalcidoid wasps, most of which are parasitoids of whiteflies and scale insects. Convergence in body form due to shared parasitoid life histories presents many challenges to taxonomy and phylogeny of the group. Previous studies have indicated that Aphelinidae is highly polyphyletic. Analyzing 18S and 28S ribosomal DNA under a variety of optimality criteria (likelihood, bayesian analysis and parsimony) confirms the polyphyly of the family, though we find strong support for the monophyly of the subfamily Aphelininae. The main focus of this study is molecular phylogenetics of the subfamily Coccophaginae. Earlier analyses have suggested that Coccophaginae is monophyletic if the enigmatic genus Coccobius is excluded. However, Coccobius shares heteronomous hyperparasitic development with other members of the Coccophaginae; females develop as primary endoparasitoids of their hosts whereas males develop as hyperparasitoids on their own or different parasitoid species. If Coccobius is not a member of the Coccophaginae, then this unusual life history has evolved twice in the Hymenoptera. With improved taxon sampling, Coccobius appears to be a coccophagine, with weak support for the monophyly of the subfamily if Coccobius is included. This study is the first molecular phylogeny to include the coccophagine genera Pteroptrix and Dirphys. Pteroptrix is often thought closely related to Encarsia, and possibly nested within it, though this assertion is not supported by our results. The genus Dirphys, however, is consistently nested within Encarsia. Improved sampling of both genes and taxa should further elucidate the relationships among coccophagine genera.