Description: Thallus crustose, endosubstratic to very thinly episubstratic, poorly evident, the hyphae strongly amyloid, I+ blue. Apothecia lecideine, 0.15-0.6 mm across, sessile, constricted at base, with a flat to slightly convex disc, and a thick, persistent proper margin. Proper exciple vilis-type, radially composed of textura oblita, up to 60 µm wide, the outer part brown-red to black, K-, N+ intensifying purple, the inner part colourless and strongly I+ blue; epithecium brown; hymenium colourless, without oil droplets, c. 80 µm high; hypothecium colourless, strongly amyloid. Asci 8-spored, Bacidia-type. Ascospores 1-septate, brown, broadly ellipsoid, slightly constricted at septum, 12-15 x 7.5-9 µm, Buellia-type, with a psilate to microrugulate ornamentation. Pycnidia black, sessile. Conidia bacilliform, 2.5-4 µm long. Photobiont chlorococcoid. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: a mainly arctic-alpine, probably circumpolar early coloniser of siliceous pebbles in windy situations and of recently eroded granitic boulders, with optimum near and above treeline; more widespread in the Alps but probably overlooked.