Ant crickets and their secrets: Myrmecophilus acervorum is not always parthenogenetic (Insecta: Orthoptera: Myrmecophilidae)

Abstract Previously considered as a thelytokous parthenogenetic species, the widespread ant cricket Myrmecophilus acervorum actually turns out to have a mixed reproductive system: our recent surveys in the central part of its distribution area has revealed the presence of both sexes. Detailed morphological and morphometric descriptions of the previously unknown males are here provided. New data on species distribution in south-eastern Europe are presented, including the first records of M. balcanicus in Bulgaria and of M. nonveilleri in Bulgaria and Hungary. Phylogenetic and phylogeographic analyses have revealed several haplotypes of M. acervorum in Europe, with six of them forming a parthenogenetic clade in populations distributed west of the Carpathians. We tested our samples for bacterial infection by Wolbachia and, surprisingly, Wolbachia was identified only in populations with both sexes and no amplification was obtained from parthenogenetic populations. Phylogenetic analyses performed with sequences pertaining to five nominal species related to M. acervorum, yielded topological congruent trees with four well-supported groups: one group with M. acervorum samples, the second group with M. nonveilleri samples, the third group with M. fuscus and M. gallicus samples, and the fourth group with samples of M. balcanicus. We performed species delineation tests on our sequences, which delimited between four to seven putative species.