Review of the genus Cheilosia Meigen, 1822 (Diptera: Syrphidae) from the Caucasus, with the description of 14 new species

A checklist and an identification key to the species of the hover fly genus Cheilosia (Diptera: Syrphidae: Rhingiini) from the Caucasus Region is presented, based on literature research and new field expeditions. The field expeditions and barcoding analysis resulted in 14 species new to science: Cheilosia (Cheilosia) aurantia sp. nov., C. (C.) borjomi sp. nov., C. (C.) caucasi sp. nov., C. (C.) confusa sp. nov., C. (C.) gemmula sp. nov., C. (C) inarmata sp. nov., C. (C.) megaclama sp. nov., C. (C.) pogonias sp. nov., C. (C.) ushguliensis sp. nov., C. (C.) vansteenisi sp. nov., C. (Montanocheila) contrasta sp. nov., C. (M.) rufa sp. nov., C. (Taeniochilosia) ouwehandae Bot sp. nov. and C. (T.) longifacies sp. nov. Further, Cheilosia circassica Ståhls & Barkalov, 2017 syn. nov. is herewith considered junior synonym of Cheilosia armeniaca Stackelberg, 1960, and we recognize Cheilosia aenigmatosa Barkalov, 1993 stat. rev. as a distinct species and not a junior synonym of Cheilosia pollinifacies Stackelberg, 1968. After our survey, we consider Cheilosia caucasogenita Kuznetzov, 1997 to be a doubtful species. Our extensive genetic analysis based on DNA barcodes including other European Cheilosia taxa clusters all members of the subgenus Taeniochilosia Oldenberg, 1916 in a well-supported group. A short discussion on the Cheilosia fauna of the Caucasus Region is provided, detailing the presence of the different subgenera and the high intraspecific morphological variability within Cheilosia in the Caucasus.