Anamorph: conidiomata immersed in pale necrotic areas of the thallus or apothecial margin surrounded by a black line, 105–135 μm diam., ± spherical, black in surface view. Conidiomatal wall 7–10 μm thick, brown, dark brown around the ostiole, composed of 2–4 (–5) layers of cells 8–10 × 3–4.5 μm in size, inner cells hyaline. Conidiogenous cells 6–7.5 × 4–5.5 μm, short-ampulliform to subglobose, proliferating percurrently. Conidia 5–7 × 3–4 μm, ellipsoidal, with a small guttule near each apex.
Teleomorph: ascostromata perithecia, dispersed, immersed in the apothecial margins, the hymenium and the gradually bleaching branches of the host thallus, visible as black dots, often with paler apical dots indicating the ostioles, more rarely on the apothecial disk and then almost sessile. Ascomata 200–300 μm diam., ± spherical with a shortly conical neck. Peridium 10-20 µm thick, composed of of 3–4 layers of dark brown fairly thick-walled angular cells, with flattened branched hyphae extending over the surface. Interascal tissue of thick-walled pseudoparaphyses 1–1.5 μm diam. Asci 90–110 × 9–12 μm, cylindrical, fairly long-stalked, the apex rounded and strongly thickened, thick-walled and fissitunicate with a small ocular chamber, 8-spored. Ascospores ± uniseriate to half-overlapping, (13–) 14–20 × 5–6.5 (–7) μm, dark brown, 3-septate, a few only with 1 or 2 septa, the cell above the primary septum slightly wider than the others, slightly to strongly constricted at the septa, with a distinct verruculose ornamentation, without an epispore or gelatinous sheath.
Not eavulated by Woods & Coppins, but listed as Nationally Rare.
On thalli and apothecia of Ramalina species, most frequently found on R. fastigiata; causing necrosis of the infected area.
Quite frequently encountered in the northern parts of the Scottish Highlands, also in Devon. BLS map here.