Review of the Palaearctic Acomopterella Zaitzev (Diptera, Sciaroidea, Mycetophilidae)

Abstract. The distribution of Acomopterella species in the Palaearctic region has been re-examined in this study, using recently collected material. The European species was found to be distributed in the eastern Palaearctic as well. A second Palaearctic species from Honshu (Japan) is herein described. The morphology of adult specimens was studied by light microscopy and scanning electron microscopy. The shape of functional specialized setae on mid tibiae in Acomopterella and seven further fungus gnat genera is described and the suitability of this character for systematic studies is discussed. Details of a “hind tibial organ” are described. The position of Acomopterella in the tribe Gnoristini is briefly discussed. Acomopterella is found to be more closely related to Speolepta Edwards, 1925, than to any other recent genus.