Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Squamules: up to 3 mm wide, elongate, adjacent or partly ascending, weakly concave to plane upper surface: medium brown, dull, becoming densely pruinose, smooth margin: concolorous with upper side, often slightly up-turned, not pruinose, crenulate or lobed upper cortex: up to 140 µm thick, composed of rather thick-walled hyphae with somewhat angular lumina, containing crystals of calcium oxalate but no lichen substances medulla: containing lichen substances but no calcium oxalate lower cortex: poorly developed, composed of mainly periclinally oriented hyphae, not containing calcium oxalate lower surface: pale brown Apothecia: up to 1.5 mm diam., laminal, convex and immarginate even when young, medium brown to reddish brown, epruinose ascospores: ellipsoid, 11-15 x 5.5-7 µm (n=20) Pycnidia: unknown Spot tests: upper cortex K-, C-, KC-, P-, medulla K-, C-, KC-, P+ red Secondary metabolite: pannarin. Substrate and ecology: on soil in open habitats, in Vizcaíno subdivision of Sonoran Desert and in Californian coastal scrub, up to 440 m World and Sonoran distribution: rare in southern California and Baja California. Notes: The species is recognized by the densely pruinose squamules with an up-turned, epruinose margin, and by the presence of pannarin which is unique in Psora.