Description contributed by Graham Kinsey, CABI, based on Wehmeyer (1933).
Anamorph: Phomopsis pustulata (Sacc.) Died. (1911). Conidiogenous cells ca 14 µm long. Alpha-conidia 10-13 x 3.5 µm.
Teleomorph: stromata on host surface as truncate-conical or angular pustules with a central blackened disc through which a small cluster of ostioles is erumpent, often each pustule is surrounded by a slightly raised or blackened ridge caused by the abutting of the ventral zone. Ascomata 250-640 µm, in definite clusters, collectively erumpent, ostioles stout-cylindrical. Asci 67-80 x 6-8 µm, clavate, with a refractive apical ring. Ascospores 12-15(-16) x 3-4(-5) µm.