Review of the Messor semirufus complex (Hymenoptera, Formicidae) in Greece.

Messor is a diverse genus of Myrmicinae with 168 extant species and subspecies. In the Mediterranean, some of its taxa historically were classified as members of the Messor instabilis group (sensu Santschi), of which 19 are known from the eastern Mediterranean. Here, the Messor semirufus complex of the Balkan Peninsula that assembles a distinct subsection of members of the instabilis group is defined and treated. In total, five species are recorded, including three that are new. Messor atanassovii Atanassov, 1982 is redescribed and confirmed for Bulgaria (Thracian Plain, Struma, and Mesta Valley, Pirin Mt., and Eastern Rhodopi) and Greece (Epirus, Ionian Islands, Central and Eastern Macedonia, and Thraki). Three species are described as new to science: Messor danaes Salata, Georgiadis & Borowiec, sp. nov. (Cyclades: Serifos), Messor kardamenae Salata & Borowiec, sp. nov. (Dodecanese: Kos, Nisyros, Rhodes, and Tilos), and Messor veneris Salata, Georgiadis & Borowiec, sp. nov. (Cyclades: Milos). The fifth member of the complex, Messor creticus Borowiec & Salata, 2019, maintains its status of Cretan endemic. [ABSTRACT FROM AUTHOR]