Description contributed by Graham Kinsey, CABI, based on Wehmeyer (1933).
Anamorph: not known.
Teleomorph: stromata mainly on decorticated areas of host as widely effuse and heavily blackened areas of the wood, often with small papillate swellings caused by the perithecia, visible through the bark only as scattered exposed areas of this blackening or as isolated ostioles. Ascomata 400-750 µm diam, scattered singly in the wood and erumpent separately, ostioles conical to short-cylindrical or elongate-sinuous. Asci 50-60 x 6-8 µm, clavate, with a refractive apical ring. Ascospores 10-12.5 x 3.5-5 µm, broad fusiform-ellipsoidal, constricted at the septum at maturity, 2-guttulate.