Ant crickets and their secrets:Myrmecophilus acervorumis 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.

Distribution of Myrmecophilus acervorum (Panzer, 1799) (Orthoptera: Myrmecophilidae) in Poland

“…However, recent studies from Romania show that both sexes occur in a part of its range. A phylogenetic and phylogeographic analysis revealed the existence of few haplotypes (Iorgu et al 2021).…”

“…Males were only historically recorded in the Pomeranian Lakeland (Bazyluk 1957), however this information has to be treated as uncertain, as there is no possibility to check specimens. Recently all males reported from Germany turned out to be female nymphs (Iorgu et al 2021), which indicates the possibility that the supposed Polish males could in fact also be females.…”

“…The genus Myrmecophilus Berthold, 1887 consists of 49 species that can be found in Europe, Asia, Africa, North America, Australia and Oceania (Cigliano et al 2022). Myrmecophilus acervorum (Panzer, 1799) occurs in Armenia, Austria, Belarus, Bulgaria, Czech Republic, Denmark, France, Greece, Netherlands, Spain, Kazakhstan, Lithuania, Luxembourg, North Macedonia, Germany, Poland, Russia (Kaliningrad Oblast), Romania, Slovakia, Sweden, Ukraine, Uzbekistan and Hungary (Zacher 1917, Stach 1926, Stalling 2013, Childebaev et al 2014, Ostrovsky 2016, Bubenko 2017, Lebedeva 2017, Stalling et al 2017, Iorgu et al 2021. It is a myrmecophilous species with a symphilic character, however it can also be found far from ant nests during dispersal (Franc et al 2015).…”