Distribution: N - Frl (Tretiach & Hafellner 2000), Lomb (Nascimbene & al. 2021), Piem (Isocrono & al. 2004, Isocrono & Piervittori 2008), VA (Piervittori & al. 2004), Emil (Fariselli & al. 2020). C - Tosc (Nascimbene & al. 2021), Sar.
Description: Thallus crustose, invisible or consisting of a few, scattered, yellowish green or yellowish grey, flat, often crenulate areoles. Apothecia lecanorine, 1-2.5 mm across, sessile and constricted at base, with a pale yellowish brown to medium brown, flat to slightly convex disc, and an initially thick and prominent, then thinner, often wavy, greenish yellow to sulphur yellow thalline margin. Amphithecial cortex with an outer layer of granules, strongly gelatinized; epithecium yellowish brown, c. 15 µm thick; hymenium colourless, 55-60 µm high; paraphyses sparingly branched and anastomosing, slightly thickened at apex; 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, 12-16 x 5-7.5 µm. Pycnidia immersed, with a pale yellow-brown ostiole. Conidia acicular to arcuate. Photobiont chlorococcoid. Spot tests: thallus K- or K+ pale yellow, C-, KC+ yellow, P-; margin of apothecia (cortex and especially medulla) P+ orange-red, K+ brownish yellow. Chemistry: usnic acid in cortex, protocetraric and rangiformic acids in the apothecial margins.
Note: a southern European orophyte found on siliceous, often iron-rich rocks, mostly near and above treeline.