Buellia longispora Scheid.

Lichenised.
Substrate: siliceous rocks
Altitudinal range: from the submediterranean/colline belt (potential vegetation: mixed deciduous forests dominated by Quercus and Carpinus) to the montane belt (potential vegetation: deciduous forests dominated by Fagus sylvatica and closed coniferous forests with Picea abies)
Note: a species of the B. dispersa-group with a white thallus reacting K+ yellow, then red, a I+ blue medulla, sessile apothecia, narrowly ellipsoid ascospores with a rugulate ornamentation (to 30 µm long); on steep rock faces of siliceous rocks, from the Alps known from a few localities below the subalpine belt.
Italy: Trentino Alto Adige;