Thallus: crustose, continuous or rimose-areolate to verrucose-areolate, verrucose or verruculose; prothallus: not visible or whitish gray areoles: thin or thick, opaque or glossy , ecorticate; surface: whitish yellow to yellowish gray or orange gray, smooth, epruinose, with an indistinct margin, esorediate; Apothecia: subimmersed when young, sessile when mature or sessile or constricted at the base to almost subpedicilate, 0.4-1.2 mm in diam., lecanorine disc: dark brown to blackish brown, plane, epruinose margin: concolorous with thallus, thick, persistent, even or prominent, entire or flexuose, smooth, entire or verruculose or crenulate, without a parathecial ring amphithecium: present, hyaline, with numerous algal cells, with small and large crystals, large crystals insoluble in K, corticate; cortex: indistinct, uniform, interspersed, 15-40 µm thick parathecium: hyaline, containing crystals insoluble in K epihymenium: blackish brown to greenish black (turning green in K), color of pigmentation altering in K, without crystals hymenium: hyaline, clear; paraphyses: not thickened or slightly thickened (up to 3 µm wide) apically, olivaceous; subhymenium: hyaline, 15-20 µm thick; hypothecium: hyaline, without oil droplets asci: clavate, 8-spored ascospores: hyaline, simple, broadly ellipsoid, 8.5-12.5 x 5-6.5 µm; wall: less than 1 µm thick Pycnidia: not seen Spot tests: thallus and apothecial margin K+ yellow, C+ orange, P+ pale orange Secondary metabolites: arthothelin (major), atranorin (major), chloroatranorin (minor), 2,4-dichloronorlichexanthone (trace), 2,5-dichloronorlichexanthone (trace), 4,5-dichloronorlichexanthone (minor), and thiophanic acid (major). Substrate and ecology: on exposed siliceous rocks in the Sonoran Desert Sonoran distribution: endemic to southwestern North America, so far known only from Isla Margarita along the Pacific coast of Baja California Sur. Notes: Lecanora ryanii is characterized by the presence of xanthones, the dark apothecial discs and the yellow thallus. It is somewhat similar to L. gangaleoides and L. pseudogangaleoides, but readily distinguished from these by the different chemistry. Lecanora gangaleoides lacks xanthones, while the Southern Hemispherean L. pseudogangaleoides contains usnic acid.