Revision of the Highly Specialized Ant Genus Discothyrea (Hymenoptera: Formicidae) in the Afrotropics with X-Ray Microtomography and 3D Cybertaxonomy

Discothyrea Roger, 1863 is a small genus of proceratiine ants with remarkable morphology and biology. However, due to cryptic lifestyle, Discothyrea are poorly represented in museum collections and their taxonomy has been severely neglected. We perform the first comprehensive revision of Discothyrea in the Afrotropical region through a combination of traditional and three-dimensional (3D) cybertaxonomy based on microtomography (micro-CT). Species diagnostics and morphological character evaluations are based on examinations of all physical specimens and virtual analyses of 3D surface models generated from micro-CT data. Additionally, we applied virtual dissections for detailed examinations of cephalic structures to establish terminology based on homology for the first time in Discothyrea. The complete datasets comprising micro-CT data, 3D surface models and videos, still images of volume renderings, and colored stacked images are available online as cybertype datasets (Hita Garcia et al. 2019, http://doi.org/10.5061/dryad.3qm4183). We define two species complexes (D. oculata and D. traegaordhi complexes) and revise the taxonomy of all species through detailed illustrated diagnostic character plates, a newly developed identification key, species descriptions, and distribution maps. In total, we recognize 20 species; of which, 15 are described as new. We also propose D. hewitti Arnold, 1916 as junior synonym of D. traegaordhi Santschi, 1914 and D. sculptior Santschi, 1913 as junior synonym of D. oculata Emery, 1901. Also, we designate a neotype for D. traegaordhi to stabilize its status and identity, and we designate a lectotype for D. oculata. The observed diversity and endemism are discussed within the context of Afrotropical biogeography and the oophagous lifestyle.