Ants, an ecologically successful and numerically dominant group of animals, play key ecological roles as soil engineers, predators, nutrient recyclers, and regulators of plant growth and reproduction in most terrestrial ecosystems. Further, ants are widely used as bioindicators of the ecological impact of land use. We gathered information of ant species in the Atlantic Forest of South America. The ATLANTIC ANTS data set, which is part of the ATLANTIC SERIES data papers, is a compilation of ant records from collections (18,713 records), unpublished data (29,651 records), and published sources (106,910 records; 1,059 references), including papers, theses, dissertations, and book chapters published from 1886 to 2020. In total, the data set contains 153,818 ant records from 7,636 study locations in the Atlantic Forest, representing 10 subfamilies, 99 genera, 1,114 ant species identified with updated taxonomic certainty, and 2,235 morphospecies codes. Our data set reflects the heterogeneity in ant records, which include ants sampled at the beginning of the taxonomic history of myrmecology (the 19th and 20th centuries) and more recent ant surveys designed to address specific questions in ecology and biology. The data set can be used by researchers to develop strategies to deal with different macroecological and region‐wide questions, focusing on assemblages, species occurrences, and distribution patterns. Furthermore, the data can be used to assess the consequences of changes in land use in the Atlantic Forest on different ecological processes. No copyright restrictions apply to the use of this data set, but we request that authors cite this data paper when using these data in publications or teaching events.

The ant genus Basiceros is an exclusively Neotropical group known for its cryptic habits. Based on a recent molecular phylogenetic framework, a comprehensive revisionary study of the genus is presented. Nine species are recognized, two of which are described as new (Basiceros browni sp. nov. and Basiceros tumucumaquensis sp. nov.). Basiceros redux (Donisthorpe 1939) is transferred to the genus Octostruma (O. reducta comb. nov.). As part of this revisionary work, taxonomic keys and images to all species and castes are provided. Castes and sexes (including larvae, males, and intercastes) are described for the first time for several Basiceros species. New records considerably expand the distributional range for most species. Natural history data and comments on character plasticity and convergence are also included.

The classification of ants (Hymenoptera: Formicidae) has progressed in waves since the first 17 species were described by Linnaeus in the 1758 edition of Systema Naturae. Since then, over 18,000 species-rank names have accumulated for the global myrmecofauna, of which ~14,260 living and ~810 fossil species are valid. Here, we provide a synopsis of ant biodiversity and review the history and classification of the family, while highlighting the massive growth of the field in the new millennium. We observe that major transformation has occurred for ant classification due to advances in DNA sequencing technologies, model-based hypothesis testing, and imaging technologies. We therefore provide a revised and illustrated list of diagnostic character states for the higher clades of Formicidae, recognizing that vastly more work is to be done. To facilitate discussion and the systematic accumulation of evolutionary knowledge for the early evolution of the ants, we suggest an informal nomenclatural system for the higher clades of ants, based on names currently in use and a set of names that have been democratically selected by the authors. To guide future work on ant systematics, we summarize currently available databases and present perspectives on regions in need of biodiversity exploration, challenges facing the field, and the future of ant taxonomy.

Mollusk-hunting (molluscivorous) cone snails belong to a monophyletic group in Conus, a genus of venomous marine snails. The molluscivorous lineage evolved from ancestral worm-hunting (vermivorous) snails ∼18 million years ago. To enable the shift to a molluscivorous lifestyle, molluscivorous cone snails must solve biological problems encountered when hunting other gastropods, namely: 1) preventing prey escape and 2) overcoming the formidable defense of the prey in the form of the molluscan shell, a problem unique to molluscivorous Conus. Here we show that χ-conotoxins, peptides exclusively expressed in the venoms of molluscivorous Conus, provide solutions to the above problems. Injecting χ-conotoxins into the gastropod mollusk Aplysia californica results in impaired locomotion and uncoordinated hyperactivity. Impaired locomotion impedes escape and a hyperactive snail will likely emerge from its shell, negating the protection the shell provides. Thus, χ-conotoxins are an evolutionary innovation that accompanied the emergence of molluscivory in Conus and provide solutions to problems posed by hunting other snails.

Ants of the genus Basiceros Schulz, 1906 are elusive species known only from Neotropical rainforests. Little information is available regarding their natural history, and nothing is known about the phylogenetic relationships among species within the genus. The genus has been the subject of some controversy regarding generic delimitation but is currently a member of the ‘Basiceros-genus group’ following recent classification changes. For mouthparts, labral and mandibular morphologies present considerable variation in the Basiceros-genus group, likely a result of adaptive evolution. In Basiceros, those differences can be observed in the labrum shape and the various degrees of development of the labral cleft and the clypeomandibular space. Here, in an attempt to illuminate the evolution of the group, species boundaries are tested for Basiceros. The evolutionary relationships of its species are investigated using molecular and morphological data. Bayesian inference and maximum likelihood analyses of a molecular dataset consisting of up to nine genes (three mitochondrial, six nuclear) and including samples from multiple populations of all known Basiceros taxa recovered the monophyly of the genus and of its species, with two well-resolved internal clades: the singularis clade and the disciger clade. Focusing on the female castes of Basiceros, an ancestral state reconstruction is presented for mandibles and labrum morphology. The results suggest that the labrum and clypeomandibular morphologies are highly labile, although phylogenetically important characters in the genus. Mouthpart traits indicate a strong correlated evolutionary history potentially associated with specialized feeding habits.