Anamorph; conidiomata sporodochial, pulvinate to spreading, to 15 mm diam, black or nearly so. Basal stroma conspicuous, erumpent, the outer part brown and the inner part ± hyaline. Conidiophores arising from the stroma surface, to 50 µm long x 2-5 µm diam, ± hyaline near the base, pale brown above, smooth to verrucose. Conidiogenous cells not differentiated from the upper cells of the conidiophore, meristematic, ± cylindrical, fragmenting to form the conidia. Conidia formed in long chains, 13-38 x 7-17 µm, cylindrical and rounded at the ends or cylindric-ellipsoidal, with usually three transverse septa that form early in the maturation process, the cells often dividing later with ± vertical or oblique longitudinal septa, brown to dark brown, verrucose, without a gelatinous sheath or appendages.
Teleomorph: ascostromata 250-2500 x 200-500 µm, solitary or in small groups, often lying parallel in line with the grain of the wood but not confluent, erumpent, black, becoming longitudinally striate. Peridium 50-80 µm thick. Interascal tissue of cellular pseudoparaphyses 1-2 µm diam, the walls thickened at the apices, with a mucilaginous epithecium that is often encrusted with dark pigmented crystals. Asci 100-120 x 10-18 µm, cylindrical, short-stalked, with a prominent ocular chamber, 8-spored. Ascospores Arranged biseriately, 20-38 x 6-12 µm, with (4-) 6-6 (-11) transverse septa, constricted at the median septum, the supramedian cell swollen, initally pale yellow and becoming brown at maturity, smooth, without a gelatinous sheath or appendages.