Thallus: crustose, continuous or verrucose-areolate, flat or verruculose; prothallus: not visible areoles: thin or thick, opaque, ecorticate surface: yellowish white to yellowish gray or whitish gray to gray, smooth or rough, epruinose, with an indistinct margin, sorediate soredia: granulose, 40-60 µm in diam., in well defined or confluent, white to whitish gray or pale yellow to yellowish gray or greenish white to yellowish green soralia 0.3-1 mm in diam. Apothecia: sessile or adnate, lecanorine disc: red-brown, plane, epruinose margin: concolorous with thallus, thin, persistent, even, entire or flexuose, smooth, entire or sorediate, without a parathecial ring amphithecium: present, with numerous algal cells, with numerous small crystals which dissolve in K, corticate; cortex: hyaline, indistinct, basally thickened, opaque or interspersed, 20-25 µm thick laterally, (30-)60-85(-90) µm thick basally parathecium: hyaline, lacking crystals epihymenium: red-brown to orange-brown, with pigment not dissolving in K, without crystals hymenium: hyaline, clear or inspersed with small oil droplets; paraphyses: red-brown to orange-brown, slightly thickened apically; subhymenium: hyaline, 15-20 µm thick; hypothecium: hyaline, without oil droplets asci: clavate, 8-spored ascospores: hyaline, simple, broadly ellipsoid, (10-)12-14.5(-15) x (6-)8-9.5(-10) µm; wall: less than 1 µm thick Pycnidia: not seen Spot tests: K+ yellow, C-, KC-, P- or P+ pale yellow Secondary metabolites: atranorin (major), chloroatranorin (minor). Substrate and ecology: on bark of deciduous trees World distribution: Europe and North America Sonoran distribution: Arizona. Notes: Lecanora impudens is characterized by the presence of well-defined or confluent soralia and granular soredia. This species is common in North America. It is closely related to the sorediate morphotype of L. allophana that differs in the soralium type, and the size of ascospores and apothecia.