Colonies developing from a variably developed flattened or rarely oblate basal stroma 110-180 µm diam., composed of very thick-walled strongly melanized and occluded ± globose cells, the surface appearing minutely verrucose. Anamorph: conidiophores mononematous, developing directly from the stroma and also apparently from internal vegetative hyphae, 70-150 (-200) µm long and 8-9.5 µm diam., cylindrical, often curved or kinked, dark brown to black and opaque. Conidiogenous cells formed in a compact terminal cluster of 5-20, 7.8-10.3 (-11.0) x 4.5-6.7 µm, irregularly shaped but usually ovoid to ampulliform, with a mid to dark brown outer wall and perhaps an inner hyaline layer, the conidiogenous locus broad (1.6-3.1 µm diam.), without an obvious collarette but with extensive periclinal thickening, proliferating percurrently. Conidia 11.2-15.2 (-18.6) x 1.2-1.5 µm, the base sometimes swollen to ca 1.8 µm diam., falcate, tapering towards the ± acute apex, often with a single submedian septum, hyaline, thin- and smooth-walled, with a slightly thickened basal scar ca 0.7 µm diam. Teleomorph: ascomata 400-700 µm diam., globose, black, slightly verrucose, very thick-walled, the peridium two-layered, the outer composed of dark thick-walled ± globose cells, largely obscured by melanized deposits. Interascal tissue of filiform thin-walled paraphyses. Asci cylindrical, thin-walled, not fissitunicate, the apex rounded, no apical structures seen, not blueing in iodine, 8-spored. Ascospores uniseriately arranged but commonly fusing in groups of two or three (rarely up to five), 10-12 x 8-9.5 µm, ovoid, dark brown at maturity, sometimes developing a narrow septum towards one end, without germ pores, smooth.
Teleomorph description adapted from Hughes (1951) and Matzer (1993).