Chapsa microspora Kalb  

Mycobank MB 517750

Thallus corticolous, light grey to whitish, smooth, continuous, ca. 20–50 µm thick, dull, ecorticate to endoperidermal. Photobiont layer indistinct, 10–15 µm thick, with numerous photobiont cells and the inclusion of decomposed periderm cells and of a few small calcium oxalate crystals. Medulla endophloeodal. Apothecia erumpent to prominent, roundish, 0.6–1.2 mm in diam., usually 1–3 aggregate. Margin strongly raised, deeply fissured to lobed, upright to usually strongly recurved, with a thin, pale-grey to white-felty and sometimes slightly crystalline inner surface; proper exciple free. Disc pale brown, covered by a thin to rather thick white pruina. Periphysoids distinct, ca. 20 µm long. Hymenium 50–60 µm high, clear. Epihymenium unpigmented or partially greyish, ca. 5–8 µm high. Paraphyses simple, straight, 2–2.5 µm wide; tips indistinctly moniliform to occasionally branched, adspersed with fine greyish granules. Ascospores 6–8/ascus, 2–3 seriate, hyaline, with (2–)3 transverse septae, 7–9 × 4 µm, thick-walled, with rounded ends, I–. Pycnidia not seen. Secondary chemistry (TLC): stictic acid (major), constictic acid (major), hypostictic acid (trace) and hypoconstictic acid (trace).