Comprehensive analysis of male-free reproduction in Monomorium triviale (Formicidae: Myrmicinae)

Parthenogenetic Reproduction in Strumigenys Ants: An Update

Parthenogenetic reproduction is a common feature for social Hymenoptera, as males typically develop from unfertilized eggs (arrhenotoky). Production of female offspring without the involvement of sperm (thelytoky) also exists but is rather exceptional as it has been reported for only 16 ant species so far. Three of these belong to the genus Strumigenys: S. hexamera, S. membranifera and S. rogeri. Our observations on the reproductive biology in various Oriental Strumigenys species extends this list of thelytokous ants with three more species: S. emmae, S. liukueiensis and S. solifontis. Of these six thelotykous species, S. emmae, S. membranifera and S. rogeri are known as tramp species. Reproduction without the need to fertilize eggs no doubt offers these species a considerable advantage when establishing colonies in new environments. Published histological data on S. hexamera and S. membranifera already showed that the queens possess a functional spermatheca. We now provide evidence that this is also the case for the four other thelytokous Strumigenys species. Retaining a functional spermatheca and reproductive system may keep the queens ready for the exceptional event of mating and hence increase genetic variability, as males do occur very rarely.

The complete mitochondrial genome of a parthenogenetic ant Monomorium triviale (Hymenoptera: Formicidae)

Monomorium is one of the most species-rich yet taxonomically problematic ant genus. An East Asian species, M. triviale Wheeler, W.M., 1906, is reproduced by obligate thelytokous parthenogenesis and performs strict reproductive division of labor. We sequenced the M. triviale mitogenome using next-generation sequencing methods. The circular mitogenome of M. triviale was 16,290 bp in length, consisting of 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNAs, and a single non-coding region of 568 bp. The base composition was AT-biased (82%). Gene order rearrangements were detected and likely to be unique to the genus Monomorium. We announce the M. triviale mitogenome as additional genomic resources for elucidating phylogenetic and taxonomic problems of Monomorium and comparative genomics of parthenogenetic ant species.