Anamorph: not known.
Teleomorph: stromata absent. Ascomata perithecia, oblate, 250-400 µm diam. and 250-330 µm tall, with a short ± papillate neck; scattered or in groups, immersed in the mesophyll and sometimes below a common clypeus. Clypeus dense, 400-700 µm diam., composed of ± occluded epidermal and subepiderma cells completely filled with dark thick-walled hyphae. Ascomatal wall black, leathery, composed of an outer layer of strongly pigmented thick-walled angular cells to ca 15 µm diam., and an internal layer of almost hyaline flattened tissue. Interascal tissue rather sparse, of thin-walled unbranched paraphyses 2-3 µm in diam, evanescent at maturity. Asci 110-150 x 9-10 µm, cylindrical, the apex rounded and the basal region short and tapered, rather thin-walled; apical ring hardly visible in lactic acid but staining blue in Lugol's iodine, truncate-conical with the upper part 2.5-3 µm and the lower part 2-2.5 µm diam., 3-3.5 µm in height; 8-spored. Ascospores arranged uniseriately, often partially or entirely obliquely, fusiform-ellipsoidal, hardly inaequilateral, the upper cell 14.5-16.5 (-18.5) x 5-6.5 (-8.5) µm, dark chocolate brown when mature, smooth-walled, germ slit inconspicuous, longitudinal, straight; the subsidiary cell 1.5-2 µm diam. and ca 2 µm in length, rounded, hyaline; sometimes with a broad gelatinous sheath.
Assessed on a global level as of Least Concern. Not formally assessed in the UK, but it would almost certainly be assessed in the same category. It is a common and wodespread species from a broad range of associated organisms.
Found on dead stems of a broad range of plants, in GB&I including species of Aster, Carex, Epilobium, Eupatorium, Juncus, Phragmites and Rubus.
Widely distributed, from Cornwall and the Channel Is to NW Scotland.