Distribution: N - TAA, Piem (TSB 34606), VA (Piervittori & Isocrono 1999).
Description: Thallus minutely squamulose, episubstratic, growing in very fine cracks of calciferous rocks. Squamules adpressed, scattered, 1-5 mm wide, finally deeply lobed, c. 500 μm thick, smooth, epruinose, pale to medium brown, paler at margins, the lower surface dirty white, attached by bundles of rhizines. Cortex overlain by a epinecral layer; medulla white, I-. Apothecia almost always present, lecideine, reddish brown to almost black, often crowded, sessile, to 1.5 mm across, at first with a flat disc and a prominent margin, finally convex, epruinose. Proper exciple and hypothecium thick, medium to dark brown, of conglutinated hyphae; epithecium brown; hymenium colourless, c. 65 μm high; paraphyses conglutinated, 2-2.5 μm thick, slightly swollen and brown at apex; hypothecium and lower part of hymenium with blue-black granules reacting K+ green. Asci 8-spored, clavate, with a I+ blue tholus and an internal, darker I+ tubular structure, the external gel I+ faintly blue, Porpidia-type. Ascospores 1-celled to sometimes finally 1-septate, hyaline, ellipsoid to narrowly ellipsoid, 10-15.5(-18) x 4-4.5 μm. Photobiont chlorococcoid. Spot tests; thallus and medulla K-, C-, KC-, P-, UV-. Chemistry: thallus apparently without lichen substances.
Note: a probably circumpolar, arctic-alpine lichen found in thin fissures of calciferous rocks (calcareous schist, dolomite, much more rarely pure limestone) near and especially above treeline; certainly more widespread in the Alps.