Stroma 1-5 x 0.2-0.5 µm, oblong to linear, formed between vascular bundles of the host tissue, at first immersed beneath the epidermis but becoming widely erumpent through splits in the substratum, often aggregated and sometimes coalescing, matt black, 1- to 5-loculate, the ostioles usually conspicuous but hardly papillate, the outer part composed of several layers of dark brown thick-walled textura angularis with cells 4-6 µm diam, often completely occluded by melanized material, the inner part of cells varying from textura angularis to porrecta, often vertically elongated and hyaline to pale brown, ranging from 6-12 x 2-3 µm in size.
Ascomata 120-200 µm diam, globose to shortly pyriform, often slightly flattened at the base, thin-walled, the ostiole periphysate. Peridium 15-25 µm wide, composed of compressed and sometimes vertically elongated textura angularis. Interascal tissue composed of thin-walled filamentous paraphyses to 5 µm diam. Asci 72-100 x 10-17 µm, cylindrical to cylindric-clavate, short-stalked, the walls thin at all stages of development, the apex rounded without clear apical structures, 8-spored. Ascospores arranged biseriately, 19-30 x 6-11 µm, clavate-ellipsoidal, often slightly curved near the base, hyaline, smooth- and fairly thin-walled, with a single septum near the base of the spore, lacking gelatinous appendages or sheath.
Anamorph: Conidiomata absent. Conidiophores 4-50 µm in length, ca 0.5 µm diam, usually not strongly differentiated form vegetative hyphae, not synnematous, straight or flexuous, unbranched, ± hyaline to pale brown or olivaceous, smooth, remotely septate, the septa thickened and highly refractive, formed from subglobose to doliiform mother cells 5-7 x 3-5 µm in size. Conidia formed terminally or from short side branches of the conidiophores which do not proliferate, 5.5-8 x 3-4.5 µm, lenticular, pale to mid brown, bilaterally flattened with a hyaline band at the junction of the two sides.