Altitudinal distribution: alpine belt (potential vegetation: treeless Alpine grasslands and tundras, to the lower limit of perennial snow and the equilibrium line of glaciers)
Note: a species of the B. aethalea-group with a minute grey thallus reacting K+ yellow then red, and an amyloid medulla; on nutrient-rich surfaces of siliceous rocks, lichenicolous on other crustose lichens (e.g., Acarospora fuscata, Sporastatia testudinea); widespread, but rare in the Alps.
