Taxonomic revision of the Merodon tarsatus species group (Diptera, Syrphidae)

The phytophagous hoverfly genus Merodon Meigen, 1803 (Diptera, Syrphidae) presently comprises 205 described species distributed in the Palaearctic and Afrotropical regions, and it is differentiated into multiple species groups. In this work, we revise the Merodon tarsatus species group, providing an illustrated key to species, a detailed discussion on relevant taxonomic characters, and a morphological diagnosis. We summarize morphological characteristics of the 12 species in the M. tarsatus group, together with available distributional data. Moreover, we provide descriptions for five new species, namely Merodon angustitarsis Vujić & Gilasian sp. nov., M. dumosus Vujić, Likov & Radenković sp. nov., M. latiantennatus Vujić, Popov & Prokhorov sp. nov., M. namaghijamii Vujić, Likov & Radenković sp. nov. and M. pakistanicus Vujić, Likov & Radenković sp. nov. Additionally, we describe one more species, Merodon nigroalatus Vujić, Likov & Radenković sp. nov., that belongs to the same lineage and is related to the Merodon tarsatus group based on molecular markers and structure of male genitalia, but lacks modifications of the metatarsus and sternum 4 that are the main diagnostic features of the group. Furthermore, we redefine and redescribe seven taxa of the M. tarsatus group. Following detailed analyses of type material, we revise the status of all available taxa related to M. tarsatus and we propose the following new synonyms: M. ankylogaster Hurkmans, 1993 syn. nov. (junior synonym of M. hypochrysos Hurkmans, 1993); M. persicus Hurkmans, 1993 syn. nov. (junior synonym of M. oidipous Hurkmans, 1993); and M. xanthipous Hurkmans, 1993 syn. nov. (junior synonym of M. marginicornis Hurkmans, 1993). We apply Maximum Parsimony and Maximum Likelihood analyses of the 5′ end of the mitochondrial COI gene sequences to genetically characterize species in the M. tarsatus group and the related species, M. nigroalatus Vujić, Likov & Radenković sp. nov