Unraveling cryptic species diversity in an aposematic sap beetle genus (Coleoptera: Nitidulidae: Cryptarchinae) from northern Europe

The saproxylic sap beetle Glischrochilus (Glischrochilus) quadripunctatus (Linnaeus, 1758), is associated with subcortical habitats of coniferous trees. This species is widely distributed across Europe and Siberia, and is the best known and largest European nitidulid species. A closely related cryptic species, G. (G.) tremulae sp. nov. has been discovered in a xerothermic area of SE Finland in association with old aspens. The two species exhibit a sympatric occurrence in SE Finland, on their respective host trees. We analyze the COI barcode region to compare G. (G.) quadripunctatus, G. (G.) tremulae sp. nov., and G. (Librodor) hortensis (Fourcroy, 1785). Morphological, ecological, and molecular data confirm the presence in SE Finland of two Glischrochilus s.str. species. We provide a description of the new species. The new Glischrochilus apparently represents a relictual taxon associated with old hollow aspens, and should be considered a species with inherent conservation value within European saproxylic beetle communities.