Stromata 1.5-5 mm diam., the smaller stromata ± circular in outline, the larger ones more irregular and somewhat elongated, 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, very densely crowded, uniseriate, situated in the upper part of the stroma, 200-350 µm diam. and ca 450 µm high, pyriform; ostiolar neck 70-85 µm diam. beneath the surface crust, 130-150 µm diam. in the very low, pulvinate free part, with minute but distinct radiating furrows. Peridium very thin and soft, 10-14 µm thick, brown, of an indistinct small-celled structure, black and almost opaque in the ostiolar region. Interascal tissue of sparse very thin-walled paraphyses to 4 µm diam. at the base, longer than the asci; periphyses numerous. Asci 25-30 x 3-5 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 1-1.5 µm, allantoid and almost cylindrical, the ends rounded, aseptate, pale brown, thin-walled, smooth, without a gelatinous sheath or appendages.