Stromata 0.5-2.5 (-5) mm long, 0.5-2 (-5) mm broad and 600-900 µm thick, erumpent from bark, applanate, orbicular to elliptical to irregular in outline, initially with a pale brown dehiscent surface layer, later black and very carbonaceous, applanate to convex, with finely papillate ostioles which become punctate with age. Internal tissue woody, greyish to dark brown, hardly present between the ascomata.
Anamorph: Nodulisporium-like (Periconiella-like according to Ju & Rogers, 1996).
Teleomorph: ascomata perithecia, 300-500 µm diam. and 400-700 µm tall, ovoid to globosecylindrical. Interascal tissue of copious fairly thin-walled unbranched paraphyses. Asci cylindrical, sporing part 70-90 x 8-10 µm with stipe 20-30 µm long, apical apparatus blue in iodine, 3-4 µm diam. and 1.5-2.5 µm tall, visible as a broad disc in optical section. Ascospores arranged uniseriately, 11-13 (-15) x 6.5-8.5 µm, fusiform-ellipsoidal to broadly ellipsoidal with obtuse ends, not or hardly inaequilateral, dark brown, smooth, with a straight germ slit running the full length of the spore, without a gelatinous sheath or appendages.
Not formally assessed, but would certainly be considered as of Least Concern. Noted by Dennis (1978) as rare, but there are numerous post-1980 records and the species can now be easily found over much of its host's range.
Found on recently fallen, dead branches of Fagus sylvatica. Reported rarely from other hardwood trees, mostly Betula, Corylus and Fraxinus. These records need confirmation.
Frequent throughout southern Britain, becoming scattered in northern England and quite rare in Scotland.
Known to live as an endophyte in bark. In GB&I it is not usually considered to be a pathogen and stromata only appear after death of host tissues. However, it has been associated with bark cankers, especially after periods of drought, and the species has been reported as causing disease of beech in southern Italy - possibly linked to environmental stress. It may be that increasing periods of drought in southern England over the past thirty years has contributed to spread of the species.