Diatrype disciformis  

Stromata 1.5-3 mm diam. and ca 1 mm high, ± circular in outline, densely scattered and rarely confluent, flat-topped, the disc blackish brown, interior pale brownish, lighter than the bark; immersed part of the stroma delimited by a black zone.
Anamorph: Libertella-like; described in culture by Rappaz (1987).
Teleomorph: Ascomata perithecia, densely crowded, uniseriate, situated in the upper part of the stroma, 300-400 µm diam. and ca 450 µm high, globose to pyriform; ostiolar neck ca 100 µm diam. beneath the surface crust, 140-150 µm diam. in the very low, pulvinate free part, with minute but distinct radiating furrows. Peridium very thin and soft, 15-20 µm thick, brown, of an indistinct small-celled structure, black and almost opaque in the ostiolar region. Interascal tissue not clearly developed, but periphyses numerous. Asci 25-35 x 4-5 µm (spore-bearing part), very narrowly clavate with a long tapering stalk, with a minute apical ring that does not blue in iodine. Ascospores irregularly biseriate, 5-8 x 1.5-2 µm, allantoid and almost cylindrical, the ends rounded, aseptate, pale brown, thin-walled, smooth, without a gelatinous sheath or appendages.

Description adapted from Munk (1957).