During our studies on the Diptera fauna of the Caspian Hyrcanian mixed forest, Golestan province, Iran, a new species of the genus Clistoabdominalis (Pipunculidae) was identified. In the present paper we name, describe and illustrate Clistoabdominalis hyrcania sp. nov.. An identification key to the males of the Clistoabdominalis ruralis species group from the Western Palaearctic region is provided.
Keywords: Diptera, Caspian Hyrcanian mixed forest, identification key, Shast-Kola, Beech forest.