Decoding the phylogeny of the genus <i>Merodon</i> Meigen (Diptera, Syrphidae): a synergistic approach with molecular and morphological data

The genus Merodon (Diptera: Syrphidae) is the most species-rich hoverfly genus in Europe. Recent studies have focused on resolving species-level taxonomy, species delimitation, or phenotypic traits analyses, but only a few authors have dealt with its intra-generic phylogenetic relationships. In this study, we compiled a dataset of adult morphological characters capturing the phylogenetically informative characters for the genus Merodon, as well as the most closely related co-tribal taxa. We also generated molecular data for a set of genes frequently used for molecular systematic studies of insects. Molecular and morphological datasets were analysed together to establish the formal subgeneric classification of Merodon using parsimony and maximum likelihood approaches. For the molecular dataset, the mitochondrial COI and nuclear 28S rRNA and 18S rRNA gene sequences were used, a total of 2947 bp. For the morphological dataset, 204 characters were analysed. The combined analysis involved 3151 characters and 80 taxa. Our analyses supported five subgenera within the genus Merodon described and diagnosed here: Albimerodon subgen. nov., Auremerodon subgen. nov., Avidumerodon subgen. nov., Desutumerodon subgen. nov., and Natamerodon subgen. nov.