The phytophagous hoverfly genusMerodonMeigen, 1803 (Diptera, Syrphidae), which comprises more than 160 species distributed in Palaearctic and Afrotropical regions, can be differentiated into multiple groups of species that harbor high levels of hidden diversity. In this work, theserrulatusspecies group ofMerodonis revised, providing an illustrated key to species, a detailed discussion on the taxonomic characters and a morphological diagnosis, including also the first data about the preimaginal morphology of this species group. The study includes characteristics of the 13 species of theM. serrulatusgroup, along with the available distributional data. Moreover, descriptions are provided for seven new species, namelyM. defectusVujić, Likov & Radenkovićsp. nov.,M. disjunctusVujić, Likov & Radenkovićsp. nov.,M. mediumVujić, Likov & Radenkovićsp. nov.,M. nigrocapillatusVujić, Likov & Radenkovićsp. nov.,M. nigropunctumVujić, Likov & Radenkovićsp. nov.,M. opacusVujić, Likov & Radenkovićsp. nov., andM. trianguloculusVujić, Likov & Radenkovićsp. nov.In addition, the taxaM. serrulatus(Wiedemann in Meigen, 1822),M. bequaertiHurkmans, 1993,M. hirsutusSack, 1913,M. kawamuraeMatsumura, 1916,M. sacki(Paramonov, 1936) andM. sophronHurkmans, 1993 are redefined and redescribed. Following a detailed study of the type material sourced from different entomological collections, the status of all available taxa related toM. serrulatusis revised and a new synonymy is proposed:M. tenerSack, 1913syn. nov.(junior synonym ofM. serrulatus). The identity ofM. trizonus(Szilády, 1940) could not be assessed as the type specimens are lost. Thus, the nameM. trizonusis considered asnomen dubium. The monophyly and composition of this species group are assessed through Maximum Parsimony and Maximum Likelihood analyses of the mitochondrial COI and nuclear 28S rRNA gene sequences.