Parasitoid wasps with enlarged mandibles associated with aculeate Hymenoptera: An integrative taxonomy of Chaenotetrastichus Graham and Styotrichia LaSalle (Hymenoptera: Eulophidae)

Abstract The two genera, Chaenotetrastichus Graham and Styotrichia LaSalle (Chalcidoidea: Eulophidae: Tetrastichinae), are newly recorded from the Oriental region, based on material reared from the pupae of Auplopus carbonarius (Scopoli) (Hymenoptera: Pompilidae) and a Pisoxylon species (Hymenoptera: Crabronidae), respectively, collected using trap-nests. Styotrichia pisoxylona Cao & Zhu sp. nov. is described and illustrated as a gregarious endo-parasitoid of Pisoxylon sp. The generic diagnosis, biology, and distribution of Chaenotetrastichus and Styotrichia are updated. All described species of the two genera are reviewed and a key to them is provided. Based on morphology and available sequences of the D2 expansion region of 28S ribosomal DNA (28S D2), the relationships between the two genera and other members of the subfamily Tetrastichinae are tentatively discussed. The phylogenetic analysis of 28S D2 confirms that the two genera with enlarged mandibles, which are associated with aculeate Hymenoptera, are not closely related. DNA barcodes (mitochondrial cytochrome c oxidase I, COI) of the newly described species and C. semiflavus (Girault) are provided and analyzed alongside publicly available COI sequences of related taxa. The result suggests that the genetic or species diversity of Chaenotetrastichus is underestimated.