Distribution: N - Frl, Ven (TSB 7812), TAA (Nascimbene & al. 2014, Nascimbene 2014, Nascimbene & Marini 2015, Trindade & al. 2021), Lomb (Valcuvia & Truzzi 2007b), Piem (Isocrono & al. 2004), VA (Valcuvia 2000), Emil (van den Boom & Brand 2008, Fariselli & al. 2020), Lig. C - Tosc, Abr (Nimis & Tretiach 1999). S - Cal (Puntillo 1996, van den Boom & Brand 2008), Si (Falco Scampatelli 2005).
Description: Thallus crustose, endosubstratic or episubstratic, continuous or warted-areolate, pale grey, yellowish green to ochre or greyish beige. Areoles rounded or irregularly incised, 0.1-0.2 mm in diam., slightly to strongly convex, ecorticate. Apothecia lecanorine, usually crowded, round, sessile and constricted at base, 0.2-0.7 mm across, with a pale pink, pale ochre, orange-brown, finally lead-grey to rarely dirty black, finely white- or bluish-pruinose, flat to convex disc, and a weakly prominent to level, smooth to crenulate, persistent to often finally excluded thalline margin. Thalline exciple of short-celled hyphae, laterally 20-35 µm wide at base, corticate; proper exciple up to 35 µm wide, brownish in outer part, colourless within; epithecium colourless or spotted greyish brown, with fine granules soluble in K, N+ reddish violet; hymenium colourless, 35-55 µm high; paraphyses simple or sparingly branched and anastomosing, 1-2(-2.5) µm thick, the apical cells only slightly thicker, to 3.5(-5) µm wide; hypothecium colourless or pale yellow, to 120 µm high. 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, 8-13 x 3-4.5 µm. Pycnidia semi-immersed, brown to colourless in upper part. Conidia of four types: a) 1(-3)-septate and slightly curved, 7-10.5 x 1.8-2.2 µm macroconidia (not rare); b) 1-celled and curved, 5.5-10 µm long microconidia (not rare); c) 1-celled and straight-bacilliform, 3-5 µm long mesoconidia (rare), d) 1-celled and curved, 10-15 µm long leptoconidia. Photobiont chlorococcoid. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: isousnic acid (major), 7-O-methylnorascomatic acid (major).
Note: a probably circumboreal-montane species of hard lignum and acid bark, usually in upland areas, with a mainly western distribution in Europe; certainly widespread throughout the Alps, and becoming rarer southwards.