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 tightly adnate, 4-8 cm in diam., irregularly lobate lobes: subirregular to sublinear, elongate, plane to subconvex, separate, contiguous to somewhat imbricate, 1-2 mm wide, not lobulate; apices: subrotund, smooth to crenate, eciliate upper surface: yellow-green, smooth, shiny, epruinose and faintly white maculate, moderately to densely isidiate isidia: cylindrical, simple to slightly branched, 0.04-0.08 mm in diam., 0.1-0.8 mm tall; tips: syncorticate, brown; soralia and pustulae absent medulla: white, with continuous algal layer lower surface: black, plane, sparsely to moderately rhizinate; rhizines: black, simple, 0.2-0.8 mm long Apothecia: rare, substipitate, 2-6 mm wide, laminal on thallus; disc: cinnamon-brown to dark brown; margin: smooth, pruina absent asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid, 7-9 x 4-5 µm Pycnidia: rare, immersed conidia: bifusiform, 4-6 x 1 µm Spot tests: upper cortex K-, C-, KC-, P-; medulla K+ yellow to dark red, C-, KC-, P+ orange Secondary metabolites: upper cortex with usnic acid (major); medulla with salazinic acid (major) and consalazinic acid (minor), and usually norstictic and protocetraric acids (both trace). Substrate and ecology: on acidic rocks, rarely on wood, often in open, arid to woodland habitats World distribution: Australasia, southern Africa, and southwestern North America Sonoran distribution: occasionally at lower elevations in Arizona, Chihuahua, Sonora, Sinaloa, and Baja California Sur. Notes: Xanthoparmelia isidiigera is close to X. australasica but has much thinner isidia and a more adnate thallus (see notes under X. australasica).