Biogeography and evolution of social parasitism in Australian Myrmecia bulldog ants revealed by phylogenomics.

Studying the historical biogeography and life history transitions from eusocial colony life to social parasitism contributes to our understanding of the evolutionary mechanisms generating biodiversity in eusocial insects. The ants in the genus Myrmecia are a well-suited system for testing evolutionary hypotheses about how their species diversity was assembled through time because the genus is endemic to Australia with the single exception of the species M. apicalis inhabiting the Pacific Island of New Caledonia, and because at least one social parasite species exists in the genus. However, the evolutionary mechanisms underlying the disjunct biogeographic distribution of M. apicalis and the life history transition(s) to social parasitism remain unexplored. To study the biogeographic origin of the isolated, oceanic species M. apicalis and to reveal the origin and evolution of social parasitism in the genus, we reconstructed a comprehensive phylogeny of the ant subfamily Myrmeciinae. We utilized Ultra Conserved Elements (UCEs) as molecular markers to generate a molecular genetic dataset consisting of 2,287 loci per taxon on average for 66 out of the 93 known Myrmecia species as well as for the sister lineage Nothomyrmecia macrops and selected outgroups. Our time-calibrated phylogeny inferred that: (i) stem Myrmeciinae originated during the Paleocene âˆ¼ 58 Ma ago; (ii) the current disjunct biogeographic distribution of M. apicalis was driven by long-distance dispersal from Australia to New Caledonia during the Miocene âˆ¼ 14 Ma ago; (iii) the single social parasite species, M. inquilina, evolved directly from one of the two known host species, M. nigriceps, in sympatry via the intraspecific route of social parasite evolution; and (iv) 5 of the 9 previously established taxonomic species groups are non-monophyletic. We suggest minor changes to reconcile the molecular phylogenetic results with the taxonomic classification. Our study enhances our understanding of the evolution and biogeography of Australian bulldog ants, contributes to our knowledge about the evolution of social parasitism in ants, and provides a solid phylogenetic foundation for future inquiries into the biology, taxonomy, and classification of Myrmeciinae.

Integrative taxonomy reveals cryptic diversity in North American Lasius ants, and an overlooked introduced species.

Biological invasions are a grave threat to ecosystems. The black garden ant (Lasius niger) is a pest species in Europe. Current literature states that L. niger occupies a disjunct native distribution in the Holarctic, however, based on recent work, we re-evaluate this distribution. The native range of L. niger is reconsidered based on phylogenetic relationships (nine mitochondrial and nuclear markers, 5670 bp), DNA-barcoding (98 Holarctic specimens), morphometry (88 Holarctic specimens, 19 different measurements) and subjective assessment of phenotype. The potential spread of this species is estimated using ecological niche modeling. Lasius niger is more closely related to other Palearctic species than to the Nearctic ants known under this name. The latter are described as a distinct species, L. ponderosae sp. nov. However, DNA-barcoding discovered established populations of L. niger in metropolitan areas in Canada (Vancouver and Halifax). We describe a morphometrical method to delineate L. ponderosae sp. nov. and L. niger. MtDNA diversity and divergence is high within L. ponderosae sp. nov., but low within L. niger. More than 1,000,000 km2 are suitable as a habitat for L. niger in North America. This case emphasizes the critical role of integrative taxonomy to detect cryptic species and identify potential biological invasions in their nascent stages.

Australian species of the ant genus Dolichoderus (Hymenoptera: Formicidae).

The Australian species of the ant genus Dolichoderus are revised. The fauna contains 27 species belonging to four species goups, the australis group (5 species, 2 newly described), the doriae group (6 species, 2 newly described), the scabridus poup (6 species, 1 newly described) and the scrobiculatus group (10 species, 4 newly described). The former subspecies niger Crawley and rufotibialis Clark are raised to species-level. The following nine new species are described: albamaculus sp. n., canopus sp. n., etus sp. n., gordoni sp. n., inferus sp. n., kathae sp. n., omicron sp. n., rutilus sp. n. and semiorbis sp. n. Four new synonyms are proposed: armstrongi McAreavey with reflexus Clark, glauerti Wheeler with parvus Clark, occidentalis Clark withformosus Clark and ruficornis Santschi with scabridus Roger. A neotype is designated for D. clusor Forel. The majority of species are found in southern forested areas with only a few species known from arid and tropical regions.