Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.
Thallus: crustose areolate to granulose, spreading areoles: irregularly shaped, 0.25-1 mm wide, c. 0.2-0.25 mm thick, contiguous upper surface: black, dull, rough to usually distinctly granulose isidia: absent but occasionally with ascending, elongated granules lower surface: attached by rhizohyphae Apothecia: semi-immersed to rarely sessile, 1(-2) per areole, small, 0.25-0.5 mm wide disc: at first punctiform, later open, somewhat depressed or plane, dark red, with persisting, smooth or granulose thalline margin proper exciple: thin, 7.5-10(-15) µm wide, IKI-, usually visible as a thin pale ring between the thalline margin and the apothecial disc epihymenium: reddish brown, K- hymenium: hyaline, (75-)90-110 µm tall, IKI+ blue asci: subclavate, subbiseriate, 8-spored ascospores: simple, hyaline, ellipsoid to broad ellipsoid, (10-)12.5-15(-20) x 5-7.5(-10) µm Pycnidia: immersed, broadly pyriform, hyaline, (0.05-)0.1-0.125 mm wide, simple or wall finally slightly convoluted conidia: broad ellipsoid, (2-)2.5-3.5 x 1.5-2 µm Spot tests: all negative Secondary products: none detected. Substrate and ecology: on various, often mossy rocks World distribution: across the Northern Hemisphere Sonoran distribution: Arizona, California, and Baja California Sur. Notes: For separation of Psorotichia schaereri from P. murorum see the notes under former species.