Thallus: foliose, orbicular to irregularly spreading, loosely attached, with free and subascendent apices, 4-8(-10) cm in diam., coriaceous, lobate lobes: irregularly laciniate, 512(-20) mm wide, 5-20(-40) mm long, discrete, contiguous to overlapping at margins, complex-folded-overlapping centrally, with sinuous, flat or ascending margins; apices: broadly rounded, notched or incised, slightly thickened below into a narrow, continuous or discontinuous darkened rim upper surface: dark blue-black or glaucous gray-blue when moist, pale glaucous-blue, gray or fawn-colored centrally the margins suffused dull charcoal gray to blue-gray, or becoming uniformly dark olive-brown to red-brown when dry, smooth, dull, undulate to slightly wrinkled or ridged, with minute, white, scattered, marginal maculae imparting a marbled appearance to the upper surface (x10 lens when moist), without phyllidia or soredia but isidiate isidia: minute (x10 lens), styliform-coralloid, up to 0.2 (-0.4) mm tall, brown-black, glossy, very delicate and friable, clustered along margins, and cracks or tears in upper surface, occasionally in minute clumps on upper surface medulla: white, K- photobiont: cyanobacterial lower surface: narrowly pale-buff marginally, reddish brown, to chocolate brown to brown-black centrally, tomentose from margins to center, with short and uniformly tufted (velvety) tomentum at margins that becomes slightly longer and woolly or felted centrally, the tips spreading, brush-like, without small, lateral knobs (in microscope sections), with bundles of ropy rhizines centrally; rhizines: 2-6 mm long, concolorous with tomentum, paler to whitish at tips cyphellae: concolorous with lower cortex, moderately common at margins, more widely scattered to infrequent centrally, prominent, rather small, round to irregular, 0.1-0.5 (-1.2) mm in diam., with narrow, rather flat to somewhat raised margins, free of tomentum, basal membrane white, sometimes granular-crystalline (x10 lens) Apothecia: not seen Pycnidia: occasional to rare, developed towards margins, immersed but apparent as a distinct, pale buff or brownish swelling, 0.2-0.5(-0.8) mm on diam., with a central, depressed red-brown to brown-black ostiole conidia: hyaline, bacilliform, straight, 4-5 x 1 µm Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: in pine-fir and pine-oak forest, on Alnus, Pinus ponderosa, Pseudotsuga menziesii, Quercus crassifolia, and Q.rugosa, on rhyolite, basalt, and soil, on mossy boulders, and cliff faces, 1900-3000 m World distribution: a North American endemic with a known range from southern Canada south along the Appalachian Mountains and west to Arkansas, and the Southwest (Harris 1987) Sonoran distribution: mountains in Arizona, Chihuahua, and Sinaloa. Notes: Sticta beauvoisii was typified from original material in Delise's herbarium (Galloway 1995: 171). It is characterized by having a white medulla, a cyanobacterial photobiont, rosette-forming thalli with robust, coriaceous rather thick lobes and sinuous, rather ragged, crisped, densely isidiate margins. Its isidia are dark-brown, very delicate, styliform, clustered-coralloid up to 0.4 mm tall. The lower surface is pale to dark brown, uniformly velvety-tomentose near margins to ragged or woolly tomentose centrally. Its cyphellae are prominent, round to irregular, 0.1-0.5 mm in diam., deeply urceolate with margins not noticeably raised and ±plane with surface of tomentum and with a white basal membrane. Arizona and Mexican material appears to be within the range of variation shown by specimens from the eastern USA (Harris 1987, McDonald et al. 2003).