Elachista deriventa sp. n. (Lepidoptera, Elachistidae: Elachistinae), a new species from southern Finland

Elachista (Elachista) deriventa Kaila & Mutanen sp. n. is described on the basis of specimens collected in southern Finland. The new species inhabits shady forests and Calamagrostis arundinacea is recorded as its host plant. The species is closest to E. elegans Frey, but differs from that by details in morphology and life history. Diagnostic characters and illustrations are provided for close relatives