A crustose species with a grey to brown-grey thallus that is areolate in the centre. The black prothallus is sometimes visible between the areoles. The small, black apothecia are innate and sometimes surrounded by a thalline collar.
Thallus: C-, K+- yellow turning red, UV-
In Scotland, Buellia aethelea is widespread in coastal and lowland regions where it grows on siliceous rocks, including gravestones. BLS distribution map
On gravestones, Buellia aethalea often creates mosaics with Rhizocarpon reductum.
scottishlichens.co.uk 