What UCE phylogenomics reveals about generic monophyly and the evolutionary history of an obscure ichneumonid tribe (Ichneumoninae, Phaeogenini)

With an estimated 120,000 total species and a wide range of morphological diversity and host species, ichneumonid parasitoid wasps represent one of the most spectacular and successful radiations of insects. However, the high diversity and strong tendency towards parallelisms and character reversals have presented serious challenges to understanding their evolutionary history and developing a robust classification. Recently, significant progress has been made in elucidating relationships at the subfamily and tribal levels although non-monophyletic taxa are common. It is unknown if the same level of non-monophyly is also present at the generic level.

Here, we present preliminary results of the first major test of generic monophyly of an ichneumonid tribe based on phylogenomic data. Phaeogenini is a moderately diverse tribe (~ 500 described species) comprised of small wasps that are endoparasitoids of microlepidoptera. Due to a lack of taxonomic attention, Phaeogenini is a particularly poorly-known group, even within Ichneumonidae, resulting in poorly-defined generic limits. To resolve the phylogenetic history of phaeogenine genera, an UCE phylogenomic approach was used, which allows for more comprehensive sampling via the generation of genomic-scale data from historical museum specimens. The results from a maximum likelihood analysis of 105 species in 29 genera with 66 outgroup taxa show that only a small minority of genera are reciprocally monophyletic. Massive taxonomic changes are thus required to render the genera monophyletic. Indeed, the necessary changes strain the balance between monophyly and diagnosability. Furthermore, these results also suggest that paraphyletic and polyphyletic genera are likely pervasive in Ichneumonidae.