Anamorph: only known in culture. Conidiomata pycnidial, 100-150 µm diam, depressed globose, black, the wall composed of fused interwoven hyphae. Conidia 3-4 x 1-1.5 µm in size, cylindrical with rounded ends to narrowly ellipsoidal or allantoid, hyaline, smooth, aseptate.
Teleomorph: Ascostromata 500-2000 x 300-500(-700) µm, 200-300 µm tall, erumpent through bark or appearing superficial on wood where the bark is lost, elongate, narrowly elliptical to fusiform in outline, straight or irregularly curved, ovate to ± doliiform in vertical section, constricted at the base, scattered or gregarious, superficial or nearly so, dull black, with a conspicuous longitudinal cleft and often with inconspicuous parallel striations, the cleft gradually widening to expose the hymenium, which is coloured dark brown by the ascospores and encrusted paraphysoids. Peridium with lateral walls 50-90 µm thick, composed of very dark, near opaque, thick-walled brown-black cells, basal region similar, with a layer of hyaline thin-walled cells 40-50 µm thick forming the cavity floor. Interascal tissue of paraphysoids ca 1.5 µm diam, filiform with rounded ends, hyaline, smooth, sparsely septate, branched and sometimes anastomosed, exceeding the asci and plugging the ascomatal slit when dry, occasionally with slight apical encrustation where exposed. Asci (75-)100-120 x 17-24 µm, cylindrical-clavate, stalked, tapering to a rounded or irregular base, thick-walled, fissitunicate, apex rounded, I-, 8-spored, arising in parallel from the cavity floor. Ascospores 26-37 x 7-12 µm, 3-septate (very rarely 4-septate), end cells much paler (near-hyaline), narrowly ellipsoidal-ovoid to cylindrical with rounded ends, often with one side straight, reddish brown, slightly constricted at the septa, the end cells concolorous or slightly paler than median cells.