Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Thallus: foliose, adnate to loosely adnate, 4-8 cm in diam., irregularly lobate lobes: subirregular, elongate, plane to subconvex, separate, contiguous to somewhat imbricate, 12 mm wide, not lobulate; apices: subrotund, smooth to crenate, eciliate upper surface: yellow-green but darkening centrally, smooth, shiny, epruinose and emaculate, moderately to densely isidiate isidia: initially globose, soon becoming subcylindrical and irregularly inflated, unbranched or sparsely branched, 0.07-0.12 mm in diam., 0.1-0.3 mm tall; tips: weakly epicorticate, brown, + erumpent; soralia and pustulae absent medulla: white, with continuous algal layer lower surface: pale to medium brown, plane, moderately to densely rhizinate; rhizines: pale brown, simple, 0.1-0.5 mm long Apothecia: rare, substipitate, 1-3 mm wide, laminal on thallus; disc: cinnamon-brown to dark brown; margin:smooth, pruina absent asci: clavate, 8spored ascospores: hyaline, simple, ellipsoid, 9-10 x 4-5 µm Pycnidia: not observed Spot tests: upper cortex K-, C-, KC-, P-; medulla K+ yellow becoming red, C-, KC-, P+ yellow Secondary metabolites: upper cortex with usnic acid (major); medulla with norstictic acid (major) connorstictic acid (minor). Substrate and ecology: on acidic rocks, often in open, arid to woodland habitats World distribution: predominately in central North America Sonoran distribution: occasional at intermediate elevations in Arizona, southern California, Baja California, Baja California Sur, and Chihuahua. Note: In comparison with X. dierythra, the much more common, desert species X. maricopensis has much smaller, more convex lobes and the constant occurrence of hyposalazinc acid in addition to norstictic and and connorstictic acids that are present in both species.