The new genus Wirthiotrema Rivas Plata, Kalb & Frisch. is described for the Thelotrema glaucopallens group, based on molecular and morphological evidence, with W. glaucopallens as the type species. The genus is characterized by myriotremoid thalli and apothecia, in combination with a paraplectenchymatous excipulum, I− ascospores, and stictic acid as a secondary compound. The new combinations W. glaucopallens (Nyl.) Rivas Plata & Kalb comb. nov., W. santessonii (Hale) Rivas Plata & Frisch comb. nov., and W. trypaneoides (Nyl.) Rivas Plata & Lücking comb. nov., are proposed and a key to the three species is presented.
