Thallus immersed, sometimes slightly bleaching the bark, non-lichenized. Anamorph: conidiomata pycnidia, 80-120 μm diam., with either macro- or microconidia. Conidiogenous cells irregular, usually ± cylindrical or somewhat tapering, proliferating percurrently. Macroconidia 11-13 × 2-2.5 μm, cylindrical to cylindric-ellipsoidal, 3-septate, the septa quite thick-walled, hyaline, smooth, without an epispore or gelatinous sheath. Microconidia 9-14 × ca 0.8 μm, filiform, often curved. Teleomorph: ascomata perithecia, 300-500 × 250-350 µm and up to 400 µm tall, often elliptical in outline. Involucrellum 40-50 µm thick, extending ca 50 µm beyond the ascoma edge, dark brown to black, the cells completely occluded with melanized material, the part beyond the ascoma blueish green, K+ greenish. Peridium not well differentiated from the involucrellum, the lower wall ± absent with a subhymenial layer of ± hyaline hyphal tissue 5-10 µm thick. Ostiole usually prominent and sometimes crateriform. Interascal tissue of quite thick-walled pseudoparaphyses 1.5-2 µm diam., the cells mostly 10-15 µm in length, frequently anastomosing in the upper part, covered in a narrow mucous coating. Asci 59-85 x 16-20 µm, cylindrical to cylindric-clavate at all stages of development, almost sessile, the apex rounded, very thick-walled with a distinct ocular chamber, not staining in iodine, 8-spored. Ascospores arranged biseriately, 15-21 (-22) x 5.5-6.5 µm, clavate with rounded apices, 3-septate, constricted at septa, especially the median one, the upper part noticeably broader than the lower, hyaline, thick-walled, smooth, with a well-developed gelatinous sheath ca 2 µm thick.