Thallus: crustose, continuous or rimose-areolate or verrucose-areolate; prothallus: white; areoles: flat or verruculose, thin, opaque, ecorticate; surface: yellowish white to yellowish gray or whitish gray to gray, smooth, epruinose, with an indistinct margin, esorediate; Apothecia: sessile, 0.4-1.5 mm in diam., lecanorine; disc: red-brown, plane, epruinose; margin: concolorous with thallus, thin or thick, persistent, even, entire or flexuose, smooth, entire or verruculose or granulose, without a parathecial ring; amphithecium: present, with numerous algal cells, with large crystals insoluble in K, corticate; cortex: hyaline, distinct, basally thickened, gelatinous, 15-25 µm thick laterally, (15-)20-45(-50) µm thick basally; parathecium: hyaline, containing crystals insoluble in K; epihymenium: red-brown to orange-brown, with pigment not dissolving in K, without crystals; hymenium: hyaline, clear; paraphyses: slightly thickened or capitate (up to 4 µm wide) apically, red-brown to orange-brown; subhymenium: hyaline, 15-20 µm thick, hypothecium: hyaline, without oil droplets; asci: clavate, 8-spored; ascospores: hyaline, simple, ellipsoid, (10-)10.5-15.5(-16) x (5.5-)7.5-8.5(-9) µm; wall less than 1 µm thick; Pycnidia: immersed, cerebriform; conidiophores: type II sensu Vobis; conidia: filiform, 1722 µm long; Spot tests: K+ pale yellow, C-, KC-, P- or P+ pale yellow; Secondary metabolites: atranorin (major), chloroatranorin (minor), 4-dichlorogangaleoidin (minor), gangaleoidin (major) and norgangaleoidin (minor).; Substrate and ecology: on bark or wood; World distribution: cosmopolitan, known from Africa, Asia, Australasia, Europe, North America, and South America; Sonoran distribution: Arizona and Chihuahua.; Notes: Lecanora argentata is recognized by the presence of the gangaleoidin chemosyndrome and apothecia with an amphithecium containing large crystals and a clear, egranulose epihymenium. Morphologically and chemically similar is L. chlarotera that differs in having crystals in the epihymenium and a pigment that dissolves in Lecanora subrugosa sensu Brodo is also quite similar, but lacks the gangaleoidin chemosyndrome and has a more coarsely verrucose thallus and the spore walls are thicker.