Opegrapha sawyeriana  

Thallus absent (lichenicolous).
Anamorph: pycnidia not known.
Teleomorph: ascomata developing just below the bark surface, but soon bursting through this and the host thallus and becoming superficial; single or in small groups of 2–4. Individual ascomata lirellate, (0.14–) 0.16–0.64 × 0.1–0.16 mm, to 0.11mm tall, unbranched and straight or curved, or occasionally 1-furcate, black, not pruinose; disc slit-like or sometimes a few eventually gaping. Exciple well developed laterally, ±spreading outwards below, (12–) 20–27 (–39) μm thick, dark brown to blackish brown, K± faint olivaceous tinge; basal exciple brown (slightly less intensely pigmented than the lateral exciple), 9–15 μm thick. Hymenium colourless or with the upper part dilute brownish, 50–60 μm tall, I+ blue, K/I+ blue; epithecium indistinct. Subhymenium indistinctly yellowish, K−, 5–10 μm tall. Paraphysoids sparingly branched, 1.3–1.7 μm diam. (in KOH), slightly widening above to c. 2.3 μm and sometimes with a few external minute brown granules. Asci shortly cylindrical-clavate, 30–39 × 11–12 μm, with a minute K/I+ blue ring around the top of the ocular chamber, 8-spored. Ascospores long remaining colourless, 3-septate, the upper two cells usually broader than the lower cells, 13–14.5(–16) × 3.5–4 μm; perispore thin, often indistinct; old spores sometimes becoming brown owing to presence of brown granules from the degenerating perispore.

Description adapted from Coppins et al. (2021).