Description: Thallus crustose-subplacodioid, episubstratic, up to 300 µm thick, areolate-warted, pale to dark brown, often white-pruinose, especially in sun-forms. Areoles contiguous, usually convex, (0.5-)1-2 mm across, the marginal ones subsquamulose, elongated and more or less clearly radiating. Cortex paraplectenchymatous, brown in upper part, sometimes with an epinecral layer; medulla white, thick, I-. Apothecia lecanorine, 0.7-1.8 mm across, with a brown to brown-black, usually white-pruinose, flat to slightly convex disc, and a usually paler, sometimes finally excluded thalline margin. Thalline exciple rich in algal cells; proper exciple thin, colourless to pale brown; epithecium orange-brown to reddish brown, with a colourless epipsamma, K- or K+ purple-red; hymenium colourless to patchily orange-brown, (40-)50-80 µm high, K/I+ blue; paraphyses simple or sparingly branched, 1.5-2 µm thick at mid-level, the apical cells only slightly swollen, some of them with a brown cap; hypothecium colourless to pale brown. Asci 8-spored, cylindrical to narrowly clavate, with a K/I+ blue tholus and a central non-amyloid area, Bacidia-type. Ascospores 1(-2)-septate, hyaline, ellipsoid, straight or slightly curved, thin-walled, (8-)10-14(-16) x (3-)4-6 µm. Pycnidia black, immersed. Conidia filiform, straight ot slightly curved, up to 20 µm long. Photobiont chlorococcoid. Spot tests: thallus K-, P-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a mainly Mediterranean lichen found on inclined surfaces of compact calciferous rocks at relatively low elevations, especially common on walls in villages; mainly Tyrrhenian in Italy.