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Among Meloidae, a beetle family of about 3000 species, Hycleus (Tribe: Mylabrini) is the most speciose genus with ~430 species described, widely distributed in the Old World. Relationships among those species have never been investigated, but morphological studies divided Hycleus in three main sections (Mesogorbatus, Mesoscutatus and Mesotaeniatus) and in several species groups. Recent molecular studies about the family and the Mylabrini tribe highlighted a possible paraphyly of Hcyleus with respect to the genera Ceroctis and Paractenodia. In the first part of this work, we built a time-calibrated phylogenetic tree based on five genes (nuDNA: CAD, Arginin Chinasi, 28S e Wingless; mtDNA: COI) in order to: (a) explore the phylogenetic relationships among the species of Hycleus; (b) define the relationships among Hycleus, Ceroctis and Paractenodia; (c) understand if the three sections may have a taxonomic value; (d) delineate a plausible scenario describing the biogeographic history of the genus. According to our results, four main clades were identified one of which included the species belonging to Ceroctis and Paractenodia: both taxa are now referred to Hycleus as new synonyms. The three sections resulted polyphyletic and do not have taxonomic value, whereas several species groups were confirmed. Biogeographic results indicated a Miocene origin (20 Mya) of Hycleus in the African paleo-continent. Subsequently, several dispersal events determined the spread of the genus in the Palaearctic, Saharo Sindian and Oriental Regions in different times. In the second part of the thesis, we have dealt more closely with the …