Thelidium pyrenophorellum (Servít) Hafellner

Syn.: Involucrothele pyrenophorella Servít
Lichenised. Poorly known taxon.
Substrate: calciferous rocks
Altitudinal distribution: montane belt (potential vegetation: deciduous forests dominated by Fagus sylvatica and closed coniferous forests with Picea abies)
Note: a calcicolous species with a very thin, epilithic, whitish-greyish thallus with darker dots, black, hemispherically protruding ascomata (to c. 0.25 mm in diam.), an involucrellum reaching down about half of the perithecium, adpressed above and slightly spreading further down, and 1-septate, more or less oblong ascospores, the upper cell somewhat wider and the lower cell slightly attenuated (to c. 32 µm long); only known from the type locality the Eastern Alps (Austria).
Austria: Oberösterreich;