Distribution: N - TAA (Nascimbene & Caniglia 2000), Lomb. S - Si.
Description: Thallus crustose, episubstratic, rather thick, continuous to rimose-areolate, yellowish to yellowish green when dry, green when wet, sorediate, often delimited by a blue-grey prothallus. Soredia initially developing along the margins of the areoles, but soon becoming diffuse and covering the central parts of thallus. Apothecia rare, lecanorine, more or less immersed to sessile, 0.3-1(-1.5) mm across, with a pink brown, greenish brown to dark grey, sometimes grey-pruinose, at first flat but soon convex disc, and a soon excluded thalline margin. Epithecium green to brown, with granules dissolving in K; hymenium colourless, 45-65 µm high; paraphyses mostly simple,the apical cells only slightly swollen; hypothecium colourless. Asci 8-spored, clavate, very thin-walled, with a K/I+ blue, tall tholus penetrated by a faintly amyloid apical cushion, the wall K/I-, surrounded by a blue outer layer, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid, 8-11(-16) x 3-5(-8) µm. Conidia needle-like, 13-22 µm long. Photobiont chlorococcoid. Spot tests: K+ yellow turning brownish, C-, KC+ yellow to yellow-brownish, P-, UV+ dull orange. Chemistry: usnic acid, skyrin, variable amounts of zeorin.
Note: on vertical or underhanging surfaces of siliceous rocks protected from rain in upland areas; certainly more widespread in the Alps.
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)