Two Palaearctic species of Orthonevra (Diptera: Syrphidae) under the name O. brevicornis

Abstract: During studying European material of Orthonevra Macquart, 1829 the presence of two widespread species so far interpreted as Orthonevra brevicornis (Loew, 1843) has been discovered. One species occurs from Central Europe into Transcaucasia and agrees with the taxon O. brevicornis of Loew (1843). The second species, O. atlantica Żóralski & Van de Meutter sp. nov., has its main distribution range in the Atlantic parts of Europe and is described here. We provide a redescription of O. brevicornis and designate a neotype from the type locality (Poland, Posen [= Poznań] vicinity). The most important characters for distinguishing males of these two closely related species are in the structures of the terminalia. A diagnosis and identification key to European black-legged Orthonevra species is given as well as new sequences of the cytochrome c oxidase subunit I (COI) of mitochondrial DNA (mtDNA), also known as DNA barcodes, for most of the species of this group. Some new information and changes to the known ranges of Orthonevra species are provided as a result of this revisionary work: O. frontalis (Loew, 1843) is removed from the list of species occurring in Poland; O. gemmula Violovitsh, 1979 is confirmed from Hungary; O. incisa (Loew, 1843) is confirmed from its locus typicus (Poland, Posen vicinity); and O. montana Vujić, 1999 is reported from Poland and Austria for the first time and confirmed for Germany. An explanation for some previous records published as O. plumbago (Loew, 1840) is also given.

Key words: Diptera, Syrphidae, flower flies, hoverflies, COI, distribution, DNA barcode, identification key, new species, Europe, Palaearctic Region