R e s e a r c h m o n o g r a p hAbstract. The diagnosis of the Formicidae is revised, including five new, unreversed apomorphies, of which one is a unique synapomorphy. The first global male-based key to all subfamilies is provided and illustrated, and all ant subfamilies are diagnosed for males on a global scale for the first time. three lineages of "basal ants" are assessed in detail: the Amblyoponinae, Leptanillinae, and Martialinae. the males of Martialis heureka (Martialinae) and Apomyrma (Amblyoponinae) are described. the Martialinae and Leptanillinae are diagnosed based on males, and additional diagnostic traits for the male of Amblyoponinae and worker of Martialis are provided. the placement of Scyphodon and Noonilla in the Formicidae and Leptanillinae is confirmed. Morphological characters of the Amblyoponinae, the Leptanillinae, and the Martialinae are contrasted, and potentially homologous apomorphies are signaled.

The Coleoptera provides an excellent example of the value of fossils for understanding the evolutionary patterns of recent lineages. We reevaluate the morphology of the Early Permian †Tshekardocoleidae to test alternative phylogenetic hypotheses relating to the Palaeozoic evolution of the order. We discuss prior interpretations and revise an earlier data matrix. Both Bayesian and parsimony analyses support the monophyly of Coleoptera excluding †Tshekardocoleidae (= Mesocoleoptera), and of Coleoptera excluding †Tshekardocoleidae and †Permocupedidae (= Metacoleoptera). Plesiomorphies preserved in †Tshekardocoleidae are elytra, which rest over the body in a loose tent-like manner, with flat lateral flanges, projecting beyond the abdominal apex, and abdomens that are flexible and nearly cylindrical. Apomorphies of Mesocoleoptera include shortening of the elytra and a closer fit with the flattened and probably more rigid abdomen. A crucial synapomorphy of Metacoleoptera is the tightly sealed subelytral space, which may have been advantageous during the Permian aridification. Taxon exclusion experiments show that †Tshekardocoleidae is crucial for understanding the early evolution of Coleoptera and that its omission strongly affects ancestral state polarities as well as topology, including crown-group taxa.By constraining the relationships of extant taxa to match those supported by phylogenomic analysis, we demonstrate that features shared by Archostemata with Permian stem groups are most reasonably supported as plesiomorphic and that the smooth and simplified body forms of Polyphaga, Adephaga, Myxophaga, and Micromalthidae were derived in parallel.Our study highlights the reciprocal illumination of molecular, morphological, and paleontological data, and paves the way for tip-dating analysis across the order.

No consensus exists for the homology and terminology of the male genitalia of the Hexapoda despite over a century of debate. Based on dissections and the literature, genital skeletomusculature was compared across the Hexapoda and contrasted with the Remipedia, the closest pancrustacean outgroup. The pattern of origin and insertion for extrinsic and intrinsic genitalic musculature was found to be consistent among the Ectognatha, Protura, and the Remipedia, allowing for the inference of homologies given recent phylogenomic studies. The penis of the Hexapoda is inferred to be derived from mediallyfused primary gonopods (gonopore-bearing limbs), while the genitalia of the Ectognatha are inferred to include both the tenth-segmental penis and the ninth-segmental secondary gonopods, similar to the genitalia of female insects which comprise gonopods of the eighth and ninth segments. A new nomenclatural system for hexapodan genitalic musculature is presented and applied, and a general list of anatomical concepts is provided. Novel and refined homologies are proposed for all hexapodan orders, and a series of groundplans are postulated. Emphasis is placed on the Endopterygota, for which finegrained transition series are hypothesized given observed skeletomuscular correspondences.

Fossils not only provide unique opportunity to understand the "tempo and mode" of evolution but are essential for modeling lineage-contingent diversification histories. Here, we interrogate the Mesozoic fossil record of the Aculeata, with emphasis on the ants (Formicidae), and conduct an extended series of ancestral state estimation exercises on distributions of tip-dated combined-evidence phylogenies. We developed and illustrated from ground-up a set of 576 morphological characters which we scored for 144 extant and 431 fossil taxa; we used average posterior probability support to filter this to a target matrix of 303 taxa, for which we integrated strongly filtered ultraconserved element (UCE) data for 115 living species. We also implemented reversible jump MCMC (rjMCMC) and hidden state methods to model complex behavioral characters to test hypotheses about the pathway to obligate eusociality. In addition to revising the higher classification of all sampled groups to family or subfamily level using estimated character polarities to diagnose nodes across the phylogeny, we find that the mid-Cretaceous genera †Camelomecia and †Camelosphecia form a clade which is robustly supported as sister to the total clade Formicidae. For this reason, we name this extinct clade as †@@@idae fam. nov. and provide a definition for the expanded Formicoidea. Based on our results, we recognize three major phases in the early evolution of the ants: (1) origin of ants as running-adapted huntresses during the Late Jurassic in the "stinging aggressor" guild (Aculeata) among various lineages of "sneaking parasitoids" (non-aculeate Vespina); (2) the first formicoid radiation during the Early Cretaceous, by the end of which all major extant ant linages had originated; and (3) turnover of the Formicoidea at the end-Cretaceous leading to the second formicoid radiation, i.e., the Cenozoic formicid diversification. We conclude with a concentrated series of considerations for future directions of study with this dataset and beyond.