[Imbricaria mougeotii (Schaer.) Flot., more, Parmelia mougeotii Schaer. ex D. Dietr., Parmelia mougeotii f. deminuta Servít, Parmelia mougeotii f. discreta Nyl., Parmelia mougeotii f. incurvoides Servít, Parmelia mougeotii f. leptophylla A. Massal., Parmelia mougeotii f. mougeotiana (Nyl.) Gyeln., Parmelia mougeotii f. mougeotii Schaer., Parmelia mougeotii f. platyphylla A. Massal., Parmelia mougeotii f. reagens Hillmann, Parmelia mougeotii f. sorediantha (Müll. Arg.) Gyeln., Parmelia mougeotii var. dealbata A. Massal., Parmelia mougeotii var. mougeotii Schaer., Parmelia mougeotii var. obscurata Müll. Arg., Parmelia mougeotii var. reagens (Hillmann) Erichsen]
Thallus: foliose but appearing areolate centrally, very tightly adnate to tightly adnate, 2-4 cm in diam., irregularly lobate lobes: sublinear, short, plane to subconvex, separate and contiguous to subimbricate, 0.2-0.5 mm wide, not lobulate; apices: subtruncate, brown rimmed, smooth to crenate, eciliate upper surface: dark yellow-green to at least partially brown, smooth to rugulose and becoming transversely cracked with age, shiny, epruinose and emaculate, moderately sorediate soredia: farinose, in orbicular, capitate soralia (0.5-1 mm in diam.); isidia and pustulae absent medulla: white, with continuous algal layer lower surface: black, plane, shiny, sparsely to moderately rhizinate; rhizines: dark brown to black, simple, 0.1-0.2 mm long Apothecia: very rare (not seen in Sonoran material), adnate, 1-1.5 mm wide, laminal on thallus; disc: cinnamon-brown to dark brown; margin: smooth, pruina absent asci: clavate, 8-spored ascospores: hyaline, simple, broadly ellipsoid, 8-10 x 5-6 µm Pycnidia: rare, sunken conidia: bifusiform, 5-6 x 1 µm Spot tests: upper cortex K+yellow to orange, C-, KC-, P+ orange; medulla K+ yellow becoming dark red, C-, KC-, P+ orange Secondary metabolites: upper cortex with usnic acid (major); medulla with stictic acid (major), constictic and norstictic acids (both minor), and cryptostictic and peristictic acids (both trace). Substrate and ecology: usually on acidic rocks and rarely on tree bases, often in open habitats World distribution: pantemperate to subarctic in Europe, Asia, southern Africa and western North America Sonoran distribution: occasionally at intermediate elevations in southern California in the coastal mountains. Notes: The rare X. mougeotii is the only sorediate Xanthoparmelia in the Sonoran region and appears to be restricted to habitats with maritime influence, although it is a temperate to arctic/alpine species elsewhere. Sorediate species are more common in southern South America (Nash et al. 1995) and secondarily in Australasia (Elix et al. 1986).