Description: Thallus crustose, episubstratic, rimose to verrucose-areolate, yellowish green, often delimited by a white, more or less arachnoid prothallus, sometimes subplacodioid. Areoles flat to strongly convex, thick, ecorticate. Apothecia lecanorine, constricted at base to almost stalked, 0.3-1.5 mm across, with a brown or grey-brown, but heavily white- or bluish grey-pruinose, flat to convex disc, and a thin, even, smooth thalline margin, without an inner parathecial ring. Thalilne exciple with an algal-free, strongly conglutinate eucortex and a more or less loose medullar plectenchyma in inner parts; proper exciple colourless, containing crystals soluble in K; epithecium brown to dark brown, with crystals, the pigment and the crystals dissolving in K; hymenium colourless; paraphyses slightly thickened at tips; 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, 9-14 x 6-7.5 µm. Photobiont chlorococcoid. Spot tests: thallus K+ yellow, C+ yellow, KC+ yellow, P+ pale yellow; apothecial disc (pruina) C+ yellow-orange, KC+ orange; apothecial margin C+ orange. Chemistry: thallus with atranorin (major); apothecial margin with thiophanic acid and sordidone.
Note: a chemotype distinguished by the presence of sordidone in the thallus, and thiophanic acid in the apothecial margin, known from the high Mediterranean mountains, on steeply inclined to underhanging surfaces of siliceous rocks, with optimum near and above treeline.