Taxonomic revision of the Mediterranean <i>Temnothorax rottenbergii</i> species group via integrated morphological and molecular approaches

Abstract The Temnothorax rottenbergii species group of myrmicine ants is characterized and revised in the current revisionary work. Twenty species belonging to this group—ranging across Anatolia and Levant, the European Mediterranean region, the Maghreb, and the Canary Islands—are described or redefined based on an integrative approach combining exploratory analyses of morphometric data and molecular phylogeny via ultraconserved elements. 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 draw nomenclatural consequences, the final step in taxonomic work. In this species group, we describe two new species (Temnothorax gallei sp. nov., Temnothorax lailae sp. nov.), and elevateTemnothorax balcanicus stat. nov. and ­Temnothorax scabriosus stat. nov. to species level, revive Temnothorax fuentei from synonymy and propose junior synonymy for Temnothorax annibalis numidicus syn. nov. and T. rottenbergii ernesti syn. nov. as junior synonym of Temnothorax bucheti. We describe the worker caste and provide high-quality images and distributional maps for all twenty species. Additionally, we present a decision tree as a numeric identification key that visually gives an overview of this species group.