Bryostigma lapidicola (Taylor) S.Y. Kondr. & HurThallus crustose, endosubstratic or thinly episubstratic, olive-grey to olive-brown, thin, filmy or minutely granular, usually forming <5 mm wide patches, sometimes poorly evident. Apothecia arthonioid, black, epruinose, glossy, 0.1-0.3 mm across, slightly constricted at base, with a strongly and irregularly convex disc, without a distinct proper margin. Epithecium pale green-brown or red-brown, K+ greenish; hymenium colourless or pale green, 25-30 μm high; paraphysoids very scanty, 0.5-1 μm thick, brown-capped, especially towards apices distinctly oriented horizontally; hypothecium red-brown, 30-70 μm high, K+ olive-brown. Asci 8-spored, clavate, semi-fissitunicate, the apex broad and rounded, very thick-walled. Ascospores 1-septate, hyaline, ovoid to clavate, 8-12(-14) x 2.5-4(-5) μm, often with a slightly pointed end, thick-walled. Pycnidia rare, with a pale brown, K+ olive wall. Conidia bacilliform, 3-4 x c. 0.5 μm. Photobiont chlorococcoid, the cells 6-14(-17) μm wide. Spot tests: thallus K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.