Thallus: foliose, loosely adnate, free at edges, up to 6-20 (-40) cm wide lobes: mostly 6-14 (-30) mm broad, little branched, lobules absent upper surface: pale or dark brown or gray-brown (sometimes with conspicuous roundish black areas caused by a parasite), plane or with a network of ± strong ridges but with the interspaces not deeply pitted soredia: white, gray or blue-gray to gray-black, in roundish to irregular, verruciform soralia that are mainly on ridges and along the margins medulla: white photobiont: cyanobacterial lower surface: wrinkled to smooth, pale brown, with short tomentum; pseudocyphellae: numerous, scattered, white, irregular in outline, often elongated, scarcely verruciform Apothecia: rare, 1.5-2 mm diam.; disc: dark brown Pycnidia: unknown Spot tests: cortex K-, C-, KC-, P-; medulla K+ yellow, C-, KC-, P+ orange, UV- Secondary metabolites: stictic and constictic acids and unidentified terpenes in California material (Hale and Cole 1988); earlier reports, from more northern areas, listed norstictic, stictic, and salazinic acids as accessory substances in addition to the unknown mentioned by Krog (1968). Substrate and ecology: on bark and wood, most often branches and trunks of deciduous trees and shrubs, occasional on conifers and logs, rarely on rock; c. 150-1350 m in California World distribution: western North America in the Pacific region Sonoran distribution: very rare in southern California, the southernmost collection being a Bratt specimen from Santa Barbara Co. Notes: The specimen cited above was not seen by the authors. The species was reported under the cited names in numerous articles before the name P. anomala was validly published in the paper by Ahti et al. (1987). See below under P. anthraspis for differences between the two species.