Known unknowns at our doorstep: Description of 14 Western Palaearctic species within the newly defined Aphanogmus fumipennis species group (Hymenoptera, Ceraphronoidea, Ceraphronidae)

Aphanogmus fumipennis Thomson, 1858 is one of the most frequently recorded ceraphronid parasitoid wasp species, considered to have a wide geographic distribution, numerous synonyms, and a broad host spectrum. 257 specimens with a posterior mesosomal comb, a character traditionally associated with A. fumipennis, from eight Western Palaearctic countries were examined using an integrative taxonomic approach, combining morphological study with focus on male genitalia and analyses of DNA barcode sequences.

Among those specimens, we detected 14 new species, which are all classified in a newly diagnosed A. fumipennis species group and made accessible through an identification key: Aphanogmus bispinatus Salden, Mikó & Peters, sp. nov., A. crispy Salden, Mikó & Peters, sp. nov., A. digitangulus Salden, Staverløkk, Mikó & Peters, sp. nov., A. hafti Salden, Mikó & Peters, sp. nov., A. hamatogonus Salden, Staverløkk, Mikó & Peters, sp. nov., A. harpagodalis Salden, Mikó & Peters, sp. nov., A. karlazani Salden, Mikó & Peters, sp. nov., A. kintrishi Salden, Mikó & Peters, sp. nov., A. latiharpus Salden & Peters, sp. ... mehrnov., A. tkheliharpus Salden, Mikó & Peters, sp. nov., A. trigoharpus Salden, Mikó & Peters, sp. nov., A. vashlovani Salden, Mikó & Peters, sp. nov., A. ventricoharpus Salden, Staverløkk, Mikó & Peters, sp. nov., A. zefranki Salden, Mikó & Peters, sp. nov. At least nine additional species were delimited by sequence data only, but not formally described, indicating a minimum of 23 species in the A. fumipennis species group in the Western Palaearctic. Finally, we provide a detailed genus diagnosis for Aphanogmus and discuss the status of the nominal species A. fumipennis Thomson, 1858 as a species of uncertain identity.

This study represents the first taxonomic treatment in 66 years to describe more than a single Palaearctic Aphanogmus species. It also provides the first Ceraphronoidea species descriptions from Georgia, where species richness has almost increased fivefold, and nearly doubles the number of ceraphronid species known from Germany. This demonstrates that even in historically well studied regions such as the Western Palaearctic, many parasitoid wasp groups, and Ceraphronoidea in particular, are extremely understudied. Discovering these known unknowns paves the way for further research on ecology, evolution, application and conservation of Ceraphronoidea.