Thallus: adnate, foliose, 2-7 cm in diam.; lobate; lobes: narrow, sublinear, elongate, contiguous to imbricate, plane, 1-3 mm wide; apices: subrotund, ciliate; cilia: simple, up to 0.7 mm long; upper surface: whitish to pale greenish gray, smooth, shiny, epruinose, emaculate, isidiate; isidia: cylindrical to branched, eciliate; soredia and isidia absent; medulla: white; lower surface: black, densely rhizinate, rhizines black, simple to sparingly furcate; Apothecia: very rare, laminal, sessile, 1-4 mm diam.; margin: crenate, isidiate; disc: brown; ascospores: simple, broadly ellipsoid, 12-17 x 8-10 µm; Pycnidia: rare, laminal, immersed; conidia: cylindrical, 3-5 x 0.5 µm; Spot tests: cortex K+ yellow, C-, KC-, P+ yellow; medulla K-, C+ rose, KC+ red, P-; Secondary metabolites: upper cortex with atranorin and chloroatranorin; medulla with gyrophoric acid (major), 5-O-methylhiascic, lecanoric and umbilicaric acids (all minor), 4,5-di-O-methylhiascic and 2,4,5-tri-O-methylhiascic acids (both trace).; Substrate and ecology: frequent on bark in woodlands, rare on rock; World distribution: pantemperate in North Ameica, Europe; Asia and Australasia; Sonoran distribution: SE Arizona and in the Sierra Madre Occidental region of Chihuahua and Sinaloa.