A Taxonomic Revision of the East Mediterranean Species of the Crematogaster scutellaris Complex (Hymenoptera: Formicidae)

The taxonomy of the East Mediterranean species of the Crematogaster scutellaris complex, Crematogaster schmidti (Mayr, 1853) and C. ionia Forel, 1911 sensu lato, has not yet been investigated via modern approaches like morphometric analyses. We collected morphometric data of 201 workers from 68 nests of Crematogaster schmidti and C. ionia s. l. from Slovenia, Croatia, Montenegro, North Macedonia, the Greek mainland, Crete, Bulgaria, Samos, Karpathos, Rhodes, Turkish Thrace, and Anatolia. Nest-centroid clustering suggested four distinct entities with different geographic distributions: C. schmidti from Slovenia southwards to Greece and Turkish Thrace, and three species which have been so far summarized under C. ionia: one from the Greek mainland and North Macedonia, one from Crete, and one from Samos, Karpathos, Rhodes, and Anatolia. We describe two new species: the Cretan entity as Crematogaster ariadnae sp. n. and the Balkan mainland entity as Crematogaster graeca sp. n. A key and (re)descriptions for the East Mediterranean members of the Crematogaster scutellaris complex are provided. The four species show different geographic distribution patterns, do not occur together at the same localities, and most likely speciated through long-term geographic isolation.