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which is part of the ATLANTIC SERIES data papers, is a compilation of ant records from collections (18,713 records), unpublished data (29,651 records), and published sources (106,910 records; 1,059 references), including papers, theses, dissertations, and book chapters published from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.

Forelius damiani sp. nov. is described from the dry forest of the Sierra Nevada de Santa Marta, Colombia, and additional collections from Costa Rica and Texas (USA). This new species is separated from the other rounded spiracles Forelius by the number of erect pronotal hairs, size and coloration. Comments and hypotheses about the biogeography of the genus are provided. Forelius pruinosus is recorded for the first time for Colombia.

Ants are a conspicuous biotic component within the tropical dry forest, due to their great diversity both at the species and functional level. Of all the ants, those of the genus Pheidole (Formicidae: Myrmicinae) stand out, which have been categorized as a hyperdiverse group due to the high number of species. The latter has made this group a taxonomic challenge during the development of diversity and ecology studies, therefore, local studies that offer information on the identity of the Pheidole species of a given area becomes an important resource for the decision making. The ants of the genus Pheidole in different formations of tropical dry forest in Santa Marta were studied. Thirteen species are registered, of which Pheidole guajirana extends its distributional range to the department of Magdalena, while P. impressa and P. leptina are registered for the first time in the country. The diagnosis and description of the new species P. urbana is also offered and its morphological features are compared with similar species of the “ flavens ” informal group. The species richness of the genus in the different sampling sites is evaluated and discussed. Distinctive morphological characteristics are offered for each of the species. Moreover, morphological variability is discussed, and multifocal color images are included for the soldiers (major worker) and workers (= minor worker) of each of the registered species.

The spider subfamily Schismatothelinae from Colombia is revised. One new species of Euthycaelus Simon 1889 and three new species of Schismatothele Karsch 1879 are named, as well as new geographical records provided. E. guane sp. nov. from Santander, S. hacaritama sp. nov. from Norte de Santander, S. olsoni sp. nov. from Norte de Santander and Táchira (Venezuela), and S. weinmanni sp. nov. from Cundinamarca are herein described, diagnosed and illustrated. Schismatothele is newly recorded from Colombia. Morphological aspects and diversity of the Ischnocolinae and Schismatothelinae from Colombia are discussed. An identification key to species of these subfamilies from Colombia is provided.

Spatial and temporal variation in the diversity of ants in four urban fragments of the tropical dry forest in the city of Santa Marta was evaluated. The fragments were sampled four times in the dry and rainy season, from October 2019 to January 2020, using pitfall traps, mini-Winkler bags, baits, and manual collection. Both alpha and beta taxonomic diversity and their components were quantified. The functional groups were established based on proposals for Neotropical ant species. A total of 7 subfamilies, 37 genera, and 84 species were collected. Richness varied spatially from 33 to 61 species, but between the two seasons it was 72 and 76 species. Sites N01 and N02 had greater diversity than N03 and N04. In all the fragments, soil ants were dominated by Ectatomma ruidum, but litter ants showed a structure with less dominant species. The dissimilarity between fragments was 60–80%, attributable mainly to turnover (50–70%) but not to nestedness (10%). Seventeen functional groups were identified. Taxonomic diversity of ants in urban fragments in Santa Marta showed marked spatial variation, without influence from the seasons. Despite taxonomic turnover, there was broad similarity in functional groups between the fragments, indicating ecological equivalence of species between the ant assemblages.

Colombia is a country with a high diversity of ants; however, several new taxa are still being reported for the country. Forty seven new records for the country are registered here, all in the subfamily Myrmicinae: one new species record for the genera Adelomyrmex , Allomerus , Kempfidris , Megalomyrmex , Octostruma and Tranopelta ; two for Rogeria ; five for Myrmicocrypta ; six for Procryptocerus ; seven for Cephalotes ; ten for Pheidole and eleven for Strumigenys . Three of these new records are invasive or tramp species, Pheidole indica , Strumigenys emmae , and Strumigenys membranifera . Three species are also recorded for the first time in South America: Pheidole sicaria , Procryptocerus tortuguero , and Strumigenys manis . The ant genus Kempfidris is recorded for the first time for Colombia. All species are commented. Currently, the diversity of ants in Colombia approaches 1,200 known species in 105 genera.