Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.
Thallus: squamulose, up to 2 cm diam., sometimes with radiating peripheral lobes, usually not occurring on a hypothallus upper surface: blue-gray, pruinose to scabrid, especially on the marginal lobes, sorediate soredia: coarsely granular, in marginal soralia upper cortex: paraplectenchymatous with irregularly thickened cell walls, 40-50 µm thick Apothecia: rare, up to 1 mm in diam.; thalline margin: bluish, sorediate; disc: brown; exciple: subparaplectenchymatous, 50-60 µm thick; hymenium: I+ blue-green and turning red-brown, 100-120 µm high asci: clavate with apical amyloid sheets, 8-spored ascospores: simple, colorless, ellipsoid, not known fully developed Spot tests: K+ yellow, C-, KC- and P- Secondary metabolites: atranorin and terpenoids. Substrate and ecology: mainly occurring on coarse-barked trees World distribution: southern to northern California Sonoran distribution: only known from one collection in the San Gabriel Mountains of southern California. Notes: It is characterized by a bluish, pruinose and sorediate thallus and the occurrence of atranorin. It may be the sorediate counterpart of F. leucostictoides. It is only known from a very old collection from southern California and may now be extinct there. Although it is chemically different from F. mediterranea, it is morphologically quite similar. However, F. pulveracea is distinctly pruinose and it lacks the olivaceous tinge found in F. mediterranea.