LAUSR

Simple Summary Myzocallis is a Holarctic genus of monoecious species of aphids mostly hosted by plants belonging to Fagales. To date, extensively morphological studies have been carried out on this group of aphids, but only sporadic molecular studies have been performed to understand the relationships among the different species. With the aim improve knowledges on these aspects, almost all species of the European and Mediterranean Myzocallidini species were investigated. As a consequence of the results obtained, Myzocallis (Agrioaphis) leclanti originally described as a subspecies of M. (A.) castanicola and M. (M.) schreiberi, considered a subspecies of M. (M.) boerneri, should be regarded at a rank of a full species. Moreover, the subgenus Agrioaphis, Lineomyzocallis, Neomyzocallis and Pasekia were elevated to the rank of genus, while Myzocallis remain as such. Abstract The genus Myzocallis Passerini (Hemiptera, Aphididae, Calaphidinae, Myzocallidini) is a rather primitive group of aphids currently comprising 45 species and 3 subspecies, subdivided into ten subgenera, three of them having a West Palaearctic distribution. The majority of the species inhabit Fagales plants and some of them are considered pests. Despite their ecological interest and the presence of some taxonomic controversies, there are only a few molecular studies on the group. Here, the main aims were to develop a DNA barcodes library for the molecular identification of West Palaearctic Myzocallis species, to evaluate the congruence among their morphological, ecological and DNA-based delimitation, and verify the congruence of the subgeneric subdivision presently adopted by comparing the results with those obtained for other Panaphidini species. These study findings indicate that Myzocallis (Agrioaphis) leclanti, originally described as a subspecies of M. (A.) castanicola and M. (M.) schreiberi, considered as a subspecies of M. (M.) boerneri, should be regarded at a rank of full species, and the subgenera Agrioaphis, Lineomyzocallis, Neomyzocallis, Pasekia were elevated to the rank of genus, while Myzocallis remain as such.