he native North American fire ants (Solenopsis) comprise a difficult group taxonomically that has undergone multiple revisions in the past century yet remains in a state of taxonomic uncertainty. In this study, we utilized a large set of microsatellite markers to conduct the first robust genetic analysis of the valid nominal species. Our approach used a variety of methods to test operational criteria commonly employed in species delimitation, including genotypic clustering, reproductive isolation/cohesion, and monophyly. We conclude from our results that the recognized North American fire ant species represent evolutionarily independent entities and, moreover, we confirm the presumed sister status of the desert fire ants, S. aurea and S. amblychila. However, the presence of at least two genetically divergent populations within the valid nominal species boundaries, including a western form of S. xyloni and a distinct population of S. aurea endemic to the Salton Trough, suggests that the current taxonomy does not fully capture the species-level diversity in this group. Based on morphological analyses, we proposed raising S. maniosa, junior synonym and western counterpart of S. xyloni, to full species status and, moreover, described a new species of desert fire ant, S. arieli, collected from the Salton Trough. Finally, we developed two active learning modules: a narrative-focused approach to teaching the theory of natural selection, and a data-driven activity that uses data collected in our delimitation study to explore species concepts.