Diamesa tonsa (Haliday in Walker, 1856)

The illustrations of male genitalia of this species are by Pagast (1947) (as D. thienemanni) and Serra-Tosio (1971b). The species is the most common and widespread Diamesa species in the Alps, and is also common in the Apennines (Rossaro & Lencioni 2015a, b).