Distribution: N - TAA (Etayo & van den Boom 1995), Lomb (Valcuvia 2002, 2002b), Piem, Lig (Valcuvia & al. 2000). C - Sar.
Description: Thallus crustose, episubstratic, rimose to areolate, yellowish white to reddish brown, rarely dark brown in very exposed sites; areoles of different sizes on the same thallus, usually convex. Apothecia lecanorine, 0.5-1.2 mm across, with a flat to finally convex, orange-brown to brown-black, sometimes grey-pruinose disc, a more or less concolorous, at first rather thick, finally sometimes excluded thalline margin, and often a darker pigmented proper margin visible between disc and thalline margin. Thalline exciple corticate, the cortex pseudoparenchymatous, of isodiametric cells; proper exciple of dark-pigmented, elongated hyphae; epithecium orange brown to dark brown, the pigment extending into the upper parts of hymenium, with a thin epipsamma; hymenium colourless or brownish, 45-65 μm high; paraphyses capitate, the apical cells 8-10 μm wide; hypothecium colourless. Asci 8-spored, narrowly clavate, Bacidia-type. Ascospores 3-septate, hyaline, ellipsoid, (13-)16-20(-22) x (3-)4-4.5 μm. Photobiont chlorococcoid. Spot tests: thallus and medulla K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: on steeply inclined to underhanging surfaces of calcareous rocks, often near small cracks, but also on walls of mortar, usually below the montane belt; much overlooked and confused with other species in Italy, and probably more common.