Taxonomic revision of the Mediterranean Temnothorax rottenbergii species group via integrated morphological and molecular approaches

The Temnothorax rottenbergii species group of myrmicine ants is characterized and revised in the current revisionary work. Twelve species belonging to this group in the Asia Minor, the European Mediterranean region, and Nort-West Africa are described or redefined based on an integrative approach combining exploratory analyses of morphometric data and molecular phylogeny via ultraconserved elements (UCEs). This workflow allows us to recognize monophyletic lineages, better understand certain traits' intra- and interspecific variability, and help avoid ill-defined species delimitations. Finally, we aimed to draw nomenclatural consequences, the final step in taxonomic work. In this species group, we describe two new species (T. gallei sp. n., T. lailae sp. n.), raise T. balcanicus (Santschi, 1909) stat. nov. and T. scabriosus (Santschi, 1909) stat. nov. to species level, T. fuentei (Santschi, 1919) revived from synonymy and proposed new junior synonymy for T. annibalis numidicus (Santschi, 1929) syn. nov. and T. rottenbergi ernesti (Santschi, 1909c) syn. nov. as junior synonym of T. bucheti (Santschi, 1909). We describe the worker caste and provide high-quality images and distributional maps for all eighteen species. Furthermore, we provide a decision tree as a numeric identification key that visually gives an overview of this species group.