Description: Thallus crustose, areolate, whitish to pale grey, dull, developing on the thalli of Schaereria fuscocinerea. Medulla white, amyloid, 1+ violet. Apothecia cryptolecanorine to lecideine, 0.25-0.8 mm across, innate to subsessile, with a black, epruinose, flat to convex disc, and a thin proper margin. Proper exciple dark brown to brown-black in outer part, colourless within, N-, aethalea-type; epithecium brown to olive; hymenium colourless, not inspersed with oil droplets, 40-70 µm high; hypothecium medium to dark brown. Asci 8-spored, clavate, Bacidia-type. Ascospores 1-septate, brown, strongly constricted at septum, broadly oblong, 9.5-11.5 x 5-6 µm, Buellia-type, the wall up to 1.5 µm thick, smooth. Pycnidia black, immersed. Conidia bacilliform, 3-5-4 µm long. Photobiont chlorococcoid. Spot tests: thallus and medulla K-, C-, KC-, P-. Chemistry: miriquidic acid.
Note: a mainly arctic-alpine species found on vertical surfaces of hard granitic rocks in upland areas; almost certainly present in the Alps and to be looked for there.