Bryostigma lapidicola  

Thallus effuse, usually forming small patches (<5 mm diam.) among other crusts, dull olive-grey, olive- or grey-brown, thin, minutely scurfy-granular; granules when discrete c. 20-50 μm diam. Photobiont chlorococcoid, cells 6-14(-17) μm diam.
Anamorph: conidiomata pycnidia, occasional, ca 40 μm diam., the wall pale brown, K+ olive. Conidia 3-4 × ca 0.5 μm, bacilliform.
Teleomorph: ascomata apothecia, 50-250 (-350) µm diam. and 60-100 µm tall, irregularly convex, glossy black, not pruinose. Epithecium 5-7 μm thick, pale green or red-brown, K+ pale green, composed of 2-3 rows of periclinally arranged dark-walled hyphae 1.5-2 μm diam. Hymenium 25-30 μm thick, hyaline or pale green. Hypothecium 30-70 μm thick, reddish brown, K+ dull olive-brown. Interascal tissue of very scanty pseudoparaphyses 0.5-1 μm diam. Asci 22-35 x 10-14 µm, clavate, short-stalked, the apex broad and rounded, very thick-walled, 8-spored. Ascospores 8-12 (-14) × 2.5-4 μm, 1-septate, ovoid, the upper cell broader and shorter than the lower, often with a slightly pointed apex, hyaline, fairly thick-walled, smooth, without a gelatinous sheath or appendages.
Chemistry: lichen products not detected by TLC.