Delineation of species of the Tetramorium caespitum complex (Hymenoptera, Formicidae) in Anatolia with a diagnosis of related species-complexes

The high level of morphological crypsis of the hyper-diverse Palearctic <i>Tetramoriumcaespitum</i> group have challenged taxonomists for decades. Within this group, Wagner et al. (2017) offered a multidisciplinary solution for the delimitation of ten European species of the <i>Tetramoriumcaespitum</i> complex. Anatolia, harboring a high level of endemism in ants, has never been subject of focus research within this genus. In this study, the <i>Tetramoriumcaespitum</i> complex diversity in Anatolia and the Caucasus region was investigated by examining 191 nest-samples using an in-depth integrative-taxonomic approach. Quantitative morphometric and microsatellite data of 505 and 133 workers, respectively, and genital-morphology data of 33 nests were collected. Unsupervised analyses provided independent species-hypotheses based on the morphological and molecular disciplines. Based on the final species-hypotheses, we confirm <i>T.caespitum</i> (Linnaeus, 1758), <i>T.hungaricum</i> Röszler, 1935, <i>T.indocile</i> Santschi, 1927, <i>T.caucasicum</i>Wagner et al., 2017, <i>T.impurum</i> (Foerster, 1850), <i>T.immigrans</i> Santschi, 1927, and <i>T.flavidulum</i> Santschi, 1910 as valid species of the <i>T.caespitum</i> complex occurring in Anatolia. A lectotype of <i>T.flavidulum</i> was designated. The host of the temporary social-parasitic species <i>Tetramoriumaspina</i> Wagner et al., 2018 is <i>T.caucasicum</i> instead of <i>T.immigrans</i> - as it was suggested before. An identification key to species complexes of the <i>T.caespitum</i> group and to workers of the species of the <i>T.caespitum</i> complex in Anatolia is provided. Every cluster we identified could be linked to described species and the region's species-composition is similar to those of the Balkans and Central Europe.