Wirthiotrema: a new genus for the Thelotrema glaucopallens group (Ascomycota: Ostropales: thelotremoid Graphidaceae)

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 santessonn (Hale) Rivas Plata & Frisch comb nov, and W trypaneoides (Nyl) Rivas Plata & Lucking comb nov, are proposed and a key to the three species is presented.