Description: Thallus crustose, endosubstratic to thinly episubstratic, often poorly evident, grey to dark grey brown, thin, smooth to granulose. Apothecia lecanorine, round, sessile, strongly constricted at base, 0.5-1(-1.5) mm across, with a dark brown to blackish brown, initially concave and faintly grey-pruinose, then flat to slightly convex disc, and a thick, smooth, crenulate, often paler thalline margin. Epithecium brown; hymenium colourless, 40-80 μm high, I+ blue; paraphyses simple, distinctly thickened above, conglutinate, the apical cells brown-capped. Asci 8-spored, broadly clavate, with a I+ blue tholus, a broad ocular chamber, and a broadly cylindrical axial mass, Lecanora-type. Ascospores 0(-2-6)-septate (the septation unclear in squash preparations), hyaline, ellipsoid-cylindrical, thick-walled, straight to curved, (18-)24-35(-41) x 5-6.5(-8) μm. Photobiont chlorococcoid. Spot tests: thallus K- or K+ red-brown, C-, KC-, P-, UV-. Chemistry: with variable amounts of norstictic acid.
Note: an arctic-alpine, circumpolar lichen found on bryophytes (e.g. Andreaea, Grimmia) in sites with periodic seepage of water, with optimum above treeline on siliceous substrata.
Growth form: Crustose
Substrata: soil, terricolous mosses, and plant debris