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Abstract The order Hymenoptera (wasps, ants, sawflies, and bees) represents one of the most diverse animal lineages, but whether specific key innovations have contributed to its diversification is still unknown. We assembled the largest time-calibrated phylogeny of Hymenoptera to date and investigated the origin and possible correlation of particular morphological and behavioral innovations with diversification in the order: the wasp waist of Apocrita; the stinger of Aculeata; parasitoidism, a specialized form of carnivory; and secondary phytophagy, a reversal to plant-feeding. Here, we show that parasitoidism has been the dominant strategy since the Late Triassic in Hymenoptera, but was not an immediate driver of diversification. Instead, transitions to secondary phytophagy (from parasitoidism) had a major influence on diversification rate in Hymenoptera. Support for the stinger and the wasp waist as key innovations remains equivocal, but these traits may have laid the anatomical and behavioral foundations for adaptations more directly associated with diversification. 

Abstract We investigate the species-level taxonomy and evolutionary history of Nearctic ants in the Crematogaster scutellaris group (Hymenoptera: Formicidae), drawing on evidence from morphology and UCE (ultraconserved element) phylogenomics. The New World species in this group form a well-supported clade that originated in the Late Miocene (~7.3 Mya) and subsequently diverged into three major lineages: the C. coarctata clade (south-western Nearctic), the C. opaca clade (south-western Nearctic and northern Neotropics) and the C. lineolata clade (eastern Nearctic and Caribbean, with four isolated south-west endemics). We hypothesize trans-Beringian dispersal into the New World, west-to-east movement within North America and restriction of mesophilic species to the east with increasing aridification of the west. The ancestral nesting behaviour of these ants is inferred to be ground-dwelling, and this is still the predominant condition in the arid west, whereas most species in the eastern United States are arboreal. We resurrect from synonymy nine species and describe three new species: C. detecta sp. nov. (from Nevada), C. parapilosa sp. nov. (Florida) and C. vetusta sp. nov. (Arizona). We provide a worker-based key to the 34 species of Crematogaster occurring in America north of Mexico, but emphasize that there are still ongoing taxonomic issues that need to be resolved. 

Abstract Uncovering the evolutionary history of the subfamilies Ectatomminae and Heteroponerinae, or ectaheteromorphs, is key to understanding a major branch of the ant tree of life. Despite their diversity and ecological importance, phylogenetic relationships in the group have not been well explored. One particularly suitable tool for resolving phylogeny is the use of ultraconserved elements (UCEs), which have been shown to be ideal markers at a variety of evolutionary time scales. In the present study, we enriched and sequenced 2,127 UCEs from 135 specimens of ectaheteromorph ants and investigated phylogeny using a variety of model-based phylogenomic methods. Trees recovered from partitioned maximum-likelihood and species-tree analyses were well resolved and largely congruent. The results are consistent with an expanded concept of Ectatomminae that now includes the subfamily Heteroponerinae new synonym and its single tribe Heteroponerini new combination. Eleven monophyletic groups are recognized as genera: Acanthoponera, Alfariastatus revived, Boltonia Camacho and Feitosa new genus, Ectatomma, Gnamptogenys, Heteroponera, Holcoponerastatus revived, Poneracanthastatus revived, Rhytidoponera, Stictoponerastatus revived, and Typhlomyrmex. The new phylogenetic framework and classification proposed here will shed light on the study of Ectatomminae taxonomy and systematics, as well as on the morphological evolution of the groups that it comprises. 

Messoris a diverse genus of Myrmicinae with 168 extant species and subspecies. In the Mediterranean, some of its taxa historically were classified as members of theMessor instabilisgroup (sensu Santschi), of which 19 are known from the eastern Mediterranean. Here, theMessor semirufuscomplex of the Balkan Peninsula that assembles a distinct subsection of members of theinstabilisgroup is defined and treated. In total, five species are recorded, including three that are new.Messor atanassoviiAtanassov, 1982 is redescribed and confirmed for Bulgaria (Thracian Plain, Struma, and Mesta Valley, Pirin Mt., and Eastern Rhodopi) and Greece (Epirus, Ionian Islands, Central and Eastern Macedonia, and Thraki). Three species are described as new to science:Messor danaesSalata, Georgiadis & Borowiec,sp. nov.(Cyclades: Serifos),Messor kardamenaeSalata & Borowiec,sp. nov.(Dodecanese: Kos, Nisyros, Rhodes, and Tilos), andMessor venerisSalata, Georgiadis & Borowiec,sp. nov.(Cyclades: Milos). The fifth member of the complex,Messor creticusBorowiec & Salata, 2019, maintains its status of Cretan endemic.