Stromata superficial, effused-pulvinate, orbicular to irregularly lobed, frequently fused together and spreading over the substrate surface, 10-50 mm diam x 2-3 mm thick, loosely attached to the substrate through narrow connections and thus easily separated, with sloping to less frequently abrupt margins; when young initially pure white, the central part becoming pale to lead grey or grey-brown due to conidial production; later brown to black, with reticulate cracks, the outer layer black, carbonaceous, 200-250 µm thick. Internal stromatal tissue soft, at first white, becoming grey to grey brown with age and finally disintegrating; the tissue below the perithecial layer blackish, woody, to 1.5 mm thick.
Anamorph: conidiophores not clearly distinguished, the conidiogenous cells formed from a thick layer of intertwined hyphae 2-3 µm diam., pigmented below and ± hyaline above. Conidiogenous cells 14-18 x 3-3.5 µm, cylindrical, thin-walled, proliferating sympodially with two to three denticles often visible at the apex. Conidia 5.5-7 x 2.5-3.5 µm, ovoid to fusiform-ellipsoidal, aseptate, hyaline, thin- and smooth-walled, without an epispore, gelatinous sheath or appendages.
Teleomorph: ascomata perithecia, 0.6-1.3 mm diam. x 0.9-1.5 mm high, spherical to ovoid, arranged in one layer. Ostioles conical, shiny black, coarsely papillate. Asci long-stipitate, with apical apparatus amyloid, urn-shaped, 4-7 (-9) µm high x 3.5-4 µm broad in the broadest part. Ascospores 25-31 x 7-10 µm, fusoid-inequilateral, frequently with pinched ends, dark brown, with a straight germ slit half the spore-length on the flattened side.: ascomata perithecia, 0.6-1.3 mm diam. x 0.9-1.5 mm high, spherical to ovoid, arranged in one layer. Ostioles conical, shiny black, coarsely papillate. Asci long-stipitate, with apical apparatus amyloid, urn-shaped, 4-7 (-9) µm high x 3.5-4 µm broad in the broadest part. Ascospores 25-31 x 7-10 µm, fusoid-inequilateral, frequently with pinched ends, dark brown, with a straight germ slit half the spore-length on the flattened side.
Not formally assessed, but the species is common and widespread, and unlikely to be threatened.
On rotten wood of various broadleaved trees, especially common on Fagus sylvatica.
Throughout Great Britain and Ireland. NBN Atlas page here.