Euura histrio ZMUO.

215 Euura histrio group We recognize 16 species of the histrio group in the West Palaearctic, only one of which (E. elbrus, if it is a valid species) may be absent in Fennoscandia. Based on our sequencing data, there could be one or two additional species in the West Palaearctic, but also one or two additional synonyms. The few potentially additional species cannot be morphologically clearly distinguished from E. striata, E. tenuis and / or E. septentrionalis. Neither are they genetically so distinct that separate species status is unambiguously indicated. If the one or two additional lineages are not distinct species, it is unclear under which species these should be classified. One of the lineages is perhaps not E. septentrionalis (which is on Betula), because many of the specimens have been reared from Salix. Euura amicula, E. hartigi, E. histrio, E. nigrina, E. nuorbinjargi, E. propinquator, E. rufa, E. schlueteri, E. stenogaster, and E. histriato Prous, Liston & Mutanen sp. nov. can be relatively well defined based on colouration, valvula 3 and / or lancets. These species are also well supported or at least not contradicted by nuclear data (no genetic data for E. nigrina) and often also based on host plants. Males of most species are more difficult to recognize than females, and we have largely relied on nuclear data to associate them.