The Leptopilina Förster, 1869 of the Western Palearctic, and an updated list of the world species (Hymenoptera, Figitidae, Eucoilinae)

The genus Leptopilina comprises species of parasitoid wasps that primarily attack early instar larvae of drosophilid species, some of which are well-known agricultural or nuisance pests. To unravel host-parasitoid interactions and to use parasitoids effectively in biological control, the correct taxonomic assignment is of crucial importance. In the course of the German Barcode of Life III: Dark Taxa (GBOL III: Dark Taxa) project, we assembled specimens of all seven species of Leptopilina of the Western Palearctic. Using CO1 barcode sequence analyses and morphological examination allows us to evaluate species limits in an integrative approach, to provide extended species diagnoses as well as an updated key to the species of the Western Palearctic. This work also summarizes current knowledge on Western Palearctic Leptopilina species, including their distribution, population parameters, habitats, flight periods, and hosts. We provide the first country records of three Leptopilina species for Belgium, including the non-native L. japonica , propose two species level synonymies and move one Western Palearctic species out of Leptopilina . Finally, to facilitate taxonomic research on Leptopilina in lesser-known regions, we provide a list of non-Western Palearctic species, including the moving of 13 species into Leptopilina . These changes also result in two new generic synonymies. In conclusion, Western Palearctic Leptopilina can be clearly diagnosed both morphologically and molecularly. Comparable ease of identification and cultivation, as well as the economic interest in potent biological control agents against drosophilid pests make them ideal organisms for basic and applied research.