The Polia nimbosa–imbrifera species-group

Taxonomic notes. The four Nearctic species are closely allied to the Palaearctic members of the nebulosa group according to their external and genital morphological characters but also according to the sequences of the CO1 gene. The nearly parapatric sister species P. discalis and P. piniae occur mostly in the region of the Rocky Mountains while the other two species are widely distributed in the boreo-nemoral forest zone.