Revision of the Merodon aurifer group (Diptera: Syrphidae) with new synonyms of M. testaceus Sack, 1913

The hoverfly genus Merodon Meigen, 1803 (Diptera, Syrphidae), which comprises more than 200 species is distributed in the Palaearctic and Afrotropical Region, but one species, Merodon equestris, is a pest of flower bulbs and has been invasive into New Zealand and North America. In this work, the Merodon aurifer species group, a member of the M. avidus-nigritarsis lineage, is revised. The diagnostic characters of the M. aurifer species group, and the morphological differences between M. aurifer Loew, 1862 and M. nudicorpus sp. n. are explained and illustrated, as well as their distribution map. A detailed study of the type material resulted in three new synonyms: M. distinctus Palma, 1863 is a junior synonym of M. aurifer; M. manicatus (Sack, 1938) and M. testacoides Hurkmans, 1993 are junior synonyms of M. testaceus.Lectotypes are designated for two taxa M. aurifer and M. manicatus instead of the erroneously designated types for these species in Hurkmans (1993).