Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.
Thallus: endolithic Apothecia: black, usually dispersed, convex and round, corrugate with carbonized plectenchyma, rough, (0.2-)0.5-2 mm in diam., 0.2-0.5 mm thick disc: initially red and visible but eventually obscured through buildup of carbonized plectenchyma above margin: splitting and becoming obscured or excluded true exciple: parathecium: overall c. 70 µm thick, outer layer black c. 30 µm wide, inner layer dark to pale brown epihymenium: reddish yellow, c. 15 thick, often carbonized above hymenium: reddish orange in thick section but hyaline to golden yellow in thin section, 60-110 µm tall; paraphyses: 1.6.-2 µm wide subhymenium: pale yellow, indistinct, c. 40 µm thick hypothecium: indistinct from medullary hyphae of attachment asci: clavate, 50-70 x 20-23 µm, 100+-spored ascospores: hyaline, simple, broadly ellipsoid, 3.8-6 x (1.5-)2-2.5(-2.8) µm Pycnidia: not observed Secondary metabolites: none detected. Substrate and ecology: on sandstone, gneiss, and carbonaceous rock World distribution: Europe, Asia, North America (Southwest) Sonoran distribution: Arizona. Notes: The mature apothecia of P. cyclocarpa are convex and gyrose, and can only be confused with P. lapponica whose apothecia are generally smaller. The species probably prefers water-flushed surfaces more than a strict carbonaceous substrate. This is first report of the species occurring in North America.