Caloplaca sorocarpa (Vain.) Zahlbr.

Syn.: Placodium sorocarpum Vain.
Lichenised.
Substrate: bark
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: a usually sterile lichen with a grey thallus and concolorous, circular, often raised soralia; easily overlooked, it is one of the most common sorediate crusts growing on the branches of Rhododendron; still undercollected in some parts of the Alps.
Austria: Vorarlberg; Tirol; Salzburg; Kärnten; Steiermark; Switzerland: Graubünden; Schwyz; Valais; Italy: Friuli; Trentino Alto Adige;