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 6 mm wide, elongate, imbricate, weakly concave to weakly convex upper surface: light brown or medium brown, dull, epruinose or partly pruinose, smooth or sparingly fissured margin: concolorous with upper side or white, down-turned or straight, entire or lobed upper cortex: up to 60-120 µm thick, composed of thin-walled hyphae with round lumina, not containing crystals of lichen substances, sometimes containing calcium oxalate medulla: not lichen substances, often containing calcium oxalate lower cortex: of mainly periclinally oriented hyphae, not containing calcium oxalate lower surface: white to medium brown Apothecia: up to 1.5 mm diam., laminal, convex and immarginate even when young, medium brown, epruinose or white or yellow pruinose ascospores: broadly ellipsoid, 8-11 x 6-8 µm Pycnidia: unknown Spot tests: upper cortex and medulla K-, C-, KC-, P- Secondary metabolites: none detected. Substrate and ecology: on soil and rock in open habitats, mainly in pinyon-juniper woodland, conifer forests, and Great Basin desert scrub, from 750 m to 2860 m alt. but rare below 1600 m World distribution: western North America Sonoran distribution: common in northern and central Arizona, scattered to rare in southern Arizona and California. Notes: The specimens from Mexico and most of the specimens from southern California reported by Timdal (1986) are now considered belonging in P. luridella.