A case-based course teaching integrative taxonomy delimits three new ant species in the <i>Pheidole sexspinosa</i> complex (Hymenoptera, Formicidae) from Vanuatu

There is a dwindling number of trained taxonomists across the globe, which is part of the "taxonomic impediment" to biodiversity discovery and conservation. Therefore, there is a need to train students in taxonomy and simultaneously make the taxonomic process more robust, thus reducing the misidentification of species that leads to flawed conclusions about biogeographic, ecological, and evolutionary processes. This is where an interdisciplinary approach to taxonomy, <i>i.e</i>., "integrative taxonomy," is useful because it combines traditional comparative morphology approaches with molecular phylogenetics as well as ecological and biogeographic information to resolve species boundaries more accurately. Here, we present a study that involved teaching integrative taxonomic methods in higher education utilizing a collaborative and case-based learning approach. Specifically, we provided students with a real taxonomic case study that focused on ants in the <i>Pheidole sexspinosa</i> complex from the Vanuatuan archipelago in the southwestern Pacific region. Based on a population-level phylogeny using ultraconserved elements (UCEs) as well as quantitative morphometrics and biogeography, we delimited three new species in the <i>Pheidole sexspinosa</i> complex from Vanuatu that we describe here as <i>P. epaoensis</i> <b>sp. nov.</b>, <i>P. nivanuatu</i> <b>sp. nov.</b>, and <i>P. tanakarensis</i> <b>sp. nov.</b> We also inferred a Cytochrome C Oxidase Subunit I (COI) phylogeny that includes additional populations of the <i>P. sexspinosa</i> complex from outside of Vanuatu, which supports the hypothesis that the Vanuatuan species diversified <i>in situ</i> within the archipelago. In addition, we discuss the need for an integrative taxonomic evaluation of the broader <i>Pheidole sexspinosa</i> complex as well as the utility of a collaborative and case-based learning approach in higher education to teach integrative taxonomy and biodiversity science.