Distribution: N - Frl, Ven (Nimis 1994), Piem (Clerc & al. 1999), VA (TSB 29456). C - Abr (Nimis & Tretiach 1999).
Description: Thallus (which might belong to a host lichen) crustose to subsquamulose, grey to almost black in sun-forms, to 1 mm thick, firmly attached with a constricted basis. Marginal squamules to 1 mm long and wide, more or less deeply divided, usually weakly convex; inner squamules smaller, some of them ascending and sometimes forming isidia-like outgrowths. Cortex of hyphae running parallel to the surface, overlain with a thick epinecral layer and underlain by a paraplectenchymatous tissue. Apothecia lecanorine, immersed in the thallus, 0.5-1(-1.5) mm across, round to usually undulate, with a flat to weakly convex, yellow to ochre-yellow disc, and a thick, yellow to grey, wavy margin. Exciple paraplectenchymatous, in upper part inspersed with minute brownish yellow crystals; epithecium yellow, granular; hymenium colourless, c. 60 µm high; paraphyses 2-3 µm thick at the base, the terminal cells swollen and up to 5 µm thick. Asci 8-spored, clavate, with an apical dome which is I+ blue only in the internal, lower part, interrupted in the centre by a I+ paler blue strip, Candelaria-type. Ascospores 1-celled, ellipsoid, hyaline, straight ot slightly curved, 14-18(-20) x 4.5-6 µm. Photobiont chlorococcoid. Spot tests: thallus K-, C-, KC-, P-; apothecia K- or K+ reddish-orange, C-, KC-, P-. Chemistry: apothecia with pulvinic acid derivatives. .
Note: a probably circumpolar lichen found on more or less calcareous dolomitic rocks wetted by rain in exposed habitats, often developing along small cracks, mostly near or above treeline, probably more widespread in the Alps; frequently confused, in the past, with C. aurella.