Anamorph: often associated with Phoma juniperi (Desm.) Sacc. but the connection has not been proved. Teleomorph: ascostromata perithecia, 100-150 µm diam., developing through stomata in linear rows on the undersurface of host leaves, erumpent through a greyish mass of disrupted epidermal cells, the ostiole papillate. Peridium composed of dark brown thin-walled globose to angular cells to ca 15 µm diam., more strongly pigmented in the vicinity of the ostiole. Interascal tissue absent, the asci developing in a fascicle from a cushion of hyaline ± globose cells. Asci 58-70 x 8.5-10.5 µm, ± cylindrical, short-stalked, thick-walled and fissitunicate, the apex rounded with a distinct ostiolar chamber, 8-spored. Ascospores 16-16.5 x 3.5-4 µm (only immature spores seen), cylindric-ellipsoidal, with a ± median septum, thin-walled, hyaline, smooth, apparently without an epispore, gelatinous sheath or appendages.
Holm & Holm (1977) observed that they had never seen collections with fully mature ascospores.