Fibrillithecis sprucei Mangold, Lücking & Lumbsch  

Mycobank MB 517770

Thallus corticolous, up to 10 cm diam., 200–500 µm thick, continuous; surface uneven to bumpy, light greyish green to olive-green. Thallus in section with 20–30 µm thick prosoplectenchymatous upper cortex, thick, irregular algal layer, and white medulla; calcium oxalate crystals not apparent. Apothecia erumpent, rounded to angular-rounded, 0.7–1.2 mm diam.; disc hidden by a narrow, 0.05–0.1 mm wide pore; proper margin invisible; thalline margin thick, coarsely crenulate to almost lobulate, exposing the white medulla. Excipulum pale yellow, 30–50 µm thick; laterally covered by a thick layer of algiferous, apically with radially elongate, partially free fibrils; hypothecium prosoplectenchymatous, 10–20 µm high, colourless to pale yellowish; hymenium 180–250 µm high, colourless, strongly inspersed; epithecium indistinct. Paraphyses unbranched, glabrous; periphysoids absent; asci fusiform to clavate, 150–200 x 30–40 µm. Ascospores single, oblong, richly muriform, 120–180 x 25–35 µm, 4–5 times as long as wide, with comparatively thin septa and angular lumina, colourless, I+ violet-blue. Secondary chemistry: psoromic acid and satellite substances (P+ yellow).