Integrative taxonomic revision and phylogenomics of Nylanderia Emery (Hymenoptera: Formicidae) in the Neotropics

The ant genus Nylanderia Emery comprises 125 total described species across the world. According to estimates, however, more than a hundred remain unknown to science. The Neotropics are a major center of Nylanderia biodiversity. Challenges in resolving species boundaries include: (1) high species richness and abundance worldwide; (2) ‘globetrotting’ species with widespread distributions, including those that have dispersed via human-mediated transport for hundreds of years; and (3) cryptic morphology and strong overlap in inter- and intraspecific variation in the worker caste. As in most arthropods, study of male genitalia can offer great utility for species delimitation and identification. However, male ants are under-collected and are difficult to associate with workers unless collected as part of a nest series. Therefore, they are known for less than a quarter of all described ant species. By integrating new insights from genome-scale Ultraconserved Elements (UCE) with worker and male morphology, we have identified as many as 27 putative new species in the Neotropics. These species belong to two distantly related American clades that have each dispersed independently from Asia across the Bering Strait within the last 30 million years. At least eight of these species belong to the ‘Nylanderia austroccidua complex’ that is most closely related to all Nearctic species, but ranges from Utah, USA to Corrientes, Argentina. Most other species in the Americas, however, belong to an ‘exclusively Neotropical’ clade that does not extend northward beyond southern Mexico.