Anamorph: not known in nature. In culture: on malt agar, colonies ~40mm diam after 3 wk, aerial mycelium white, dense and cottonly in the centre, more felty near the margin, reverse without pigmentation. Conidiomata developing as ill-defined black stromatal structures 0.5-1 mm diam, with an opening from which conidia ooze in pinkish masses. Conidiophores melanized, dichotomously branched, to 5 µm diam. Conidiogenous cells 8-35 x 1.5-2 µm, hardly differentiated from vegetative hyphae, irregular in shape and often appearing distorted towards the apex, proliferating sympodially, scars fairly prominent. Conidia 16-30 x 1.5-2 µm, falcate, aseptate, hyaline, the apex usually acute and the base truncate, rarely branched or nodose, thin-walled, without a gelatinous sheath or appendages. [Description derived from Rappaz, 1995].
Teleomorph: stromata developing in dead wood, more rarely in bark, effuse, the extent partly dictated by dimensions of the substratum, the host surface melanized, dark grey to black, ostioles scattered, ± conical, slightly protruding from the stroma surface. Internal stromatal tissue poorly differentiated, composed of hyphae interspersed with degraded plant cells, sometimes delimited by a brown to black zone line. Ascomata perithecia, 500-800 µm diam, 500-600 µm tall, ± globose, single or in small clusters within the stroma, sometimes compressed by the development of surrounding fruit-bodies. Peridium 10-15 µm thick, strongly melanized when mature, composed of intertwined hyphal tissue. Interascal tissue of simple paraphyses ca 3 µm diam, gradually tapering, rather thin-walled, not branched or anastomosed. Asci 73-110 x 10-11.5 µm (90-140 x 5-8 µm fide Rappaz, 1995), cylindrical, stipe 11-30 µm in length, the apex obtuse to truncate with an inconspicuous J- ring, 8-spored. Ascospores arranged obliquely uniseriately, 11.5-14.5 [mean=12.7, sd=0.65, n=71; range 11-17 fide Rappaz, 1995) x 4.5-7.2 [mean=5.9, sd=0.67, n=71] µm, ellipsoidal to fusiform-ellipsoidal, ± round in transverse section, the ends obtuse, chestnut brown when mature, with a longitudinal germ plit extending ± the whole of the length of the spore, epispore thin, without a gelatinous sheath or appendages.