Merodon chalybeus subgroup: an additional piece of the M. aureus group (Diptera, Syrphidae) puzzle

In this study, we examined the morphology, genetics and distribution of the members of the Merodon chalybeus subgroup (M. aureus species group): M. chalybeus Wiedemann in Meigen, 1822, M. minutus Strobl, 1893 and M. robustus Veselić, Vujić & Radenković, 2017. Two of the species, M. chalybeus and M. minutus, are morphologically very similar and often misidentified in the literature. Here, by employing an integrative taxonomic approach we provide strong evidence for the separation of M. chalybeus and M. minutus. Our results show their clear allopatric distribution: M. minutus on the Balkan Peninsula, Sicily, Sardinia and Corsica, while M. chalybeus is a western Mediterranean species distributed on the Iberian Peninsula and northwest Africa. Data on the distribution of M. robustus were updated, with new records from Cyprus, Israel and Turkey, besides its type locality (Samos in Greece). We provide evidence for M. chalybeus and M. minutus representing a species complex, named the M. chalybeus complex, which together with M. robustus constitute the M. chalybeus subgroup.