Distribution: N - Ven, TAA, Lomb, Piem (Isocrono & al. 2004), Lig. C - Tosc, Abr (Nimis & Tretiach 1999), Sar (Scheidegger 1993, Rizzi & al. 2011). S - Si (Scheidegger 1993, Grillo 1998, Grillo & Caniglia 2004).
Description: Thallus crustose, episubstratic, areolate, pale green grey to yellowish grey, epruinose, sometimes delimited by a black prothallus, forming 1-2(-5) cm wide patches, the areoles rather small, 0.2-1(-1.3) mm wide, flat to convex; medulla white, I-. Apothecia lecideine, 0.2-0.5 mm across, immersed, with a black, flat, epruinose disc and a thin, externally poorly visible proper margin, sometimes surrounded by a thalline collar. Proper exciple poorly developed, aethalea-type, the inner hyphae hyaline, prosoplectenchymatous, the outer hyphae parallel and usually strongly brown-pigmented; epithecium, brown to olive, N+ red; hymenium colourless to pale brown, greenish in lower part, not inspersed with oil droplets, 80-100(-120) μm high; paraphyses simple; hypothecium pale brown to brown, greenish in upper part. Asci 8-spored, clavate to cylindrical-clavate, the apical dome K/I+ dark blue with a pale, conical-pointed apical cushion (axial mass), the wall I-, but the thin outer gel I+ blue, Bacidia-type. Ascospores 1-septate, brown, ellipsoid, thin-walled throughout, (11-)13-17(-21) x 6.5-9(-11.5) μm, Buellia-type, uniformly thin-walled, the wall microrugulate. Pycnidia black, immersed. Conidia 4-5.5(-6) x 0.8-1 µm. Photobiont chlorococcoid. Spot tests: thallus K-, C+ persistently orange, P-, UV-. Chemistry: xanthones, especially arthothelin.
Note: a temperate, perhaps holarctic species found on small siliceous pebbles, but also on steeply inclined faces near the ground, below the subalpine belt.