Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Thallus: crustose, stratified, irregular, indeterminate to determinate, sometimes with obscure marginal lobes, soft, thick, not becoming loose from the substrate, up to several cm in diam. upper surface: leprose, whitish gray, often with a greenish tinge soredia: mostly coarse, up to 0.2(-0.4) mm in diam., often with short projecting hyphae medulla: distinct, white lower surface: not evident, without a tomentum Spot tests: K+ yellow, C+ red, KC-, P+ yellow to orange Secondary metabolites: alectorialic and protocetraric acids. Substrate and ecology: over mosses on rocks World distribution: Europe and North America Sonoran distribution: southern California at 1650 m. Notes: Three chemotypes are reported from Europe: I: alectorialic and protocetraric acids; II: alectorialic, psoromic, and 2'-O-demethylpsoromic acids; III: alectorialic acid alone (see Orange 1977). Only chemotype I is known from the Sonoran region.