Thallus: foliose, tightly adnate to weakly appressed and easily removed from the substrate with a knife, up to 8 (-13) cm in diam.; lobate; rarely forming discrete convex mounds lobes: narrow, sublinear, (1-) 2-4 (-7) mm wide, contiguous, plane (occasionally with upturned margins) to wrinkled in older parts and frequently imbricate; sometimes with laciniae upper surface: light mineral gray or bluish gray, becoming buff in the herbarium with age, frequently with a narrow brownish or gray brown margin; smooth, rarely becoming weakly ridged; white maculae present in some specimens pseudocyphellae: white, occasional to abundant, up to 0.4 mm, round or becoming elongate; sometimes associated with ridges asexual propagules: none lower surface: pale, whitish tan to flesh-colored sometimes darkening toward the margin; rhizines: simple to forked, thin, stringy, concolorous with the lower surface Apothecia: occasional (often absent or immature), up to 10 mm in diam., sessile to substipitate; disc: light to dark rusty-brown; exciple: concolorous with the thallus, smooth or becoming "chinky" as the cortex cracks with age asci: Lecanora-type, 8-spored ascospores: simple, hyaline, ovoid to ellipsoid, 7-14 x 6-9 µm Pycnidia: occasional to abundant (rarely absent), black conidia: filiform to rarely unciform, 3-7(-9) x 1 µm (mostly 5-6 µm) Spot tests: upper cortex K+ yellow, C-, medulla K-, C+ red , KC+ red Secondary metabolites: upper cortex with atranorin (minor or more commonly in trace amounts), medulla containing lecanoric acid (major). Substrate and ecology: on rocks (basalt, conglomerate, granite, limestone, rhyolite, sandstone, schist, volcanic) or over mosses on rocks, very rarely on bark (Fouquieria, Cupressus, Quercus) or burned wood, in oak-pine forests in Sonoran region from 400-3000 m (known from various bark and rock substrates in other areas of North America) World Distribution: North America, Mexico and South America Sonoran distribution: Arizona, Baja California, Baja California Sur, Chihuahua, Durango, and Sonora. Notes: This species was previously known as P. semansiana (Egan 2003). Although one can be reasonably certain that saxicolous material is P. graminicola, conidial measurements are preferred for positive separation from P. hypoleucites.