Beschreibung:
<jats:title>Abstract</jats:title><jats:p><jats:italic>Calligrapha</jats:italic> is a New World leaf beetle genus that includes several unisexual species in northeastern North America. Each unisexual species had an independent hybrid origin involving different combinations of bisexual species. However, surprisingly, they all cluster in a single mtDNA clade and with some individuals of their parental species, which are in turn deeply polyphyletic for mtDNA. This pattern is suggestive of a selective sweep which, together with mtDNA taxonomic incongruence and occurrence of unisexuality in <jats:italic>Calligrapha</jats:italic>, led to hypothesize that <jats:italic>Wolbachia</jats:italic> might be responsible. I tested this hypothesis studying the correlation between diversity of <jats:italic>Wolbachia</jats:italic> and well‐established mtDNA lineages in >500 specimens of two bisexual species of <jats:italic>Calligrapha</jats:italic> and their derived unisexual species. <jats:italic>Wolbachia</jats:italic> appears highly prevalent (83.4%), and fifteen new supergroup‐A strains of the bacteria are characterized, belonging to three main classes: <jats:italic>wCallA</jats:italic>, occupying the whole species ranges, and <jats:italic>wCallB</jats:italic> and <jats:italic>wCallC</jats:italic>, narrowly parapatric, infecting beetles with highly divergent mtDNAs where they coexist. Most beetles (71.6%) carried double infections of <jats:italic>wCallA</jats:italic> with another sequence class. Bayesian inference of ancestral character states and association tests between bacterial diversity and the mtDNA genealogy show that each mtDNA lineage of <jats:italic>Calligrapha</jats:italic> has specific types of infection. Moreover, shifts can be explained by horizontal or vertical transfer from local populations to an expanding lineage and cytoplasmic incompatibility between <jats:italic>wCallB</jats:italic> and <jats:italic>wCallC</jats:italic> types, suggesting that the symbionts hitchhike with the host and are not responsible for selective mtDNA sweeps. Lack of evidence for sweeps and the fact that individuals in the unisexual clade are uninfected or infected by the widespread <jats:italic>wCallA</jats:italic> type indicate that <jats:italic>Wolbachia</jats:italic> does not induce unisexuality in <jats:italic>Calligrapha</jats:italic>, although they may manipulate host reproduction through cytoplasmic incompatibility.</jats:p>