Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Thallus: squamulose, indeterminate, heteromerous, in irregular patches up to a dm or more in diam. but usually smaller squamules: plane to concave, rounded and shell-like, with sharply raised margins, undivided or with distinct marginal lobes, 1-2 mm wide, 30-70 µm thick, sometimes becoming leprose, scattered or partly becoming contiguous forming dense colonies upper surface: pale gray to green, with greenish soredia on the surface and along the margin soredia: farinose to granular, 20-50 µm in diam. upper cortex: pseudoparenchymatous and up to 10 µm thick, or hardly evident medulla: hardly evident; photobiont layer: distinct, 35-60 µm thick, composed of hyphae with mostly globose or ellipsoid cells arranged in a net-like structure surrounding groups of algal cells lower surface: white-tomentose Spot tests: all negative Secondary metabolite: zeorin. Substrate and ecology: usually on other lichens and over mosses, also on naked bark and on stone, in areas or in microhabitats with high air humidity World distribution: cosmopolitan on all continents except Antarctica Sonoran distribution: Arizona, southern California and Chihuahua from 320 to 2570 m.