Gall things considered: The taxonomy of gall wasp parasitoids in genus Ormyrus

Oak gall wasps are a species-rich insect group that induce the formation of galls on widespread oak species. Galls provide putative protection to the young gall wasp but also recruit myriad other parasites and inquilines, thus becoming ecosystems unto themselves. The closed system offered by galls, and the associated arthropod diversity within and between galls, can be applied to address broader evolutionary and ecological questions. However, the continued exploration of gall wasp biology and ecology can be complicated by the presence of cryptic species among their natural enemies. The objective of this research is to contribute to a comprehensive taxonomic revision of the gall wasp parasitoid genus Ormyrus. Across 1,789 gall collecting events between 2015-2019 in the continental United States and British Columbia, we accumulated over 525,000 galls representing 201 different oak gall types from 32 oak tree species. From these, we reared over 151,000 gall wasps. We extracted DNA from a subset of these wasps, and amplified and aligned a short segment of the mtCOI gene to generate preliminary species hypotheses. We then validated these species hypotheses using morphological taxonomic work. This study clarifies species concepts for oak gall-associated Ormyrus and informs future taxonomic study of the genus, including new species descriptions and the development of morphological identification keys.