Stromata absent, the ascomatal necks converging strongly but without linking stromatic tissue.
Ascomata perithecia, non-stromatic, formed in dense circinate clusters of 20-40 at 2-3 levels under the bark, frequently deformed by mutual pressure, dark shining brown, venter globose to subglobose, 300–400 μm diam. Peridium leathery, consisting of many layers (in total 60–80 μm thick) of textura angularis, the outer region brown with cells smaller and more rounded than those of the inner layer, hyaline and more flattened towards the centrum, surface glabrous or covered with brown, septate hyphal appendages. Perithecial necks central, black, smooth, to ca 2 mm long, 150-200 μm diam, breaking through the substratum at a single point to expose the convergent ostioles. Ascogenous hyphae discrete, hyaline, smooth, with short branches, 4-5 × 2–3 μm, producing a sympodial sequence of hyaline, ovoid to ellipsoidal cells, derived from croziers, often with mucronate apex, in dense clusters, each giving rise to an ascus, 2.5–6 × 1.5–3 μm. Interascal tissue of paraphyses, persistent, abundant, hyaline, unbranched, septate, cylindrical to clavate, apex round, apically free, much longer than asci, 80–250 μm long, in water 3-5 μm wide and constricted at the septa. Asci 8-spored, clavate with obtuse or rounded apex, tapering towards a long, filiform, stipitate base, more intensely tapering below the sporiferous portion, with a nodule at the base, in fascicles, floating freely within the centrum at maturity, pars sporifera 18–24 x 4.5-6 μm, the stipe 27-40 µm in length, apical region 0.5–2(–3) μm thick, everted apical rings (non-amyloid) often visible after ascospore release, ascospores possibly released with a fissitunicate dehiscence mechanism. Ascospores biseriate to multiseriate, in the upper third of the ascus, aseptate, hyaline, straight to slightly allantoid, smooth, 4.5-7 × ca 1μm.
Anamorph: Conidiophores hardly differentiated from vegetative hyphae, rarely branched, 1- to 2-septate, 14-30 × 2–3 μm, but mainly reduced to conidiogenous cells. Conidiogenous cells enteroblastic, hyaline, though brown in apical part, smooth, single, generally intercalary, necks cylindrical, 2–8 × 1–2 μm, ampulliform to elongate ampulliform, 7-14 × 2–3 μm, pigmented at the apical region, collarettes distinct, cylindrical to funnel-shaped, 15–2 μm long, 1.5–2 μm wide, opening 0.5–1.5 μm wide. Conidia aggregated in slimy heads, hyaline, aseptate, cylindric-ellipsoidal, with the base attenuated, 3.5–6 × 1.5–2 μm.