Staurothele orbicularis (A. Massal.) Th. Fr.

Syn.: Porphyriospora orbicularis A. Massal., Staurothele nigella (Kremp.) Dalla Torre & Sarnth.; incl. Staurothele viperae Servít
Lichenised.
Substrate: intermediate rocks (such as calciferous schists)
Altitudinal range: from the montane belt (potential vegetation: deciduous forests dominated by Fagus sylvatica and closed coniferous forests with Picea abies) to the alpine belt (potential vegetation: treeless Alpine grasslands and tundras, to the lower limit of perennial snow and the equilibrium line of glaciers)
Note: related to S. guestphalica, but with 2-spored asci; on more or less calciferous rocks in upland areas; apparently more frequent in the Western and Southern Alps.
Germany: Oberbayern; France: Alpes-de-Haute-Provence; Alpes-Maritimes; Drôme; Haute-Savoie; Vaucluse; Var; Italy: Veneto; Trentino Alto Adige;