Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Thallus: crustose, continuous or rimose areolate to verrucose; prothallus: not visible, or white areoles: flat, thin or thick, opaque or glossy, ecorticate surface: whitish gray to gray or pale green to greenish white, smooth, epruinose, with an indistinct margin, esorediate Apothecia: subimmersed when young, sessile when mature or sessile, 0.5-1.5 mm in diam., lecanorine disc: brown or gray brown, plane, heavily whitish or bluish gray pruinose margin: concolorous with thallus, thin, persistent, even or prominent, not flexuose, smooth, entire or verrucose or verruculose, without a parathecial ring amphithecium: present, with numerous algal cells, with small crystals, soluble in K, ecorticate but with a pseudocortex; pseudocortex: indistinct, basally not thickened, opaque, hyaline, (20-)2530(-35) µm thick parathecium: hyaline, lacking crystals epihymenium: brown to dark brown, with pigment dissolving in K, with crystals dissolving in K hymenium: hyaline, clear; paraphyses: slightly thickened apically, not pigmented; subhymenium: hyaline, 15-20 µm thick; hypothecium: hyaline, without oil droplets asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid, 9.5-14.5 x (5-)6.5-7.5(-8) µm; wall: less than 1 µm thick Pycnidia: not seen Spot tests: thallus and apothecial margin K+ yellow, C- or +orange to orange-red or yellow, P+ pale yellow; apothecial disc: C+ orange Secondary metabolites: containing atranorin (major), chloroatranorin (minor), eugenitol (minor), roccellic acid (major), sordidone (major) and thiophanic acid (submajor or absent). Substrate and ecology: on exposed siliceous rocks and overhangs World distribution: bipolar to sub-cosmopolitan Sonoran distribution: Arizona and southern California. Notes: Lecanora rupicola is characterized by the heavily pruinose apothecial disc lacking a parathecial ring and a whitish to yellowish gray thallus. The species is easily confused with L. bicincta; the differences between these two species are discussed under that taxon.