Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.

Thallus: squamulose, usually small, up to 3 cm diam., on a well developed hypothallus that extends beyond the margin squamules: up to 1 mm broad, with crenulate to effigurate margins upper surface: gray to grayish blue, smooth to slightly roughened, pruinose, esorediate upper cortex: paraplectenchymatous with irregularly thickened cell walls, 40-50 µm thick Apothecia: common, up to 1.5 mm diam., with a grayish, squamulose thalline margin; disc: brown; exciple: subparaplectenchymatous, 60-80 µm thick; hymenium: I+ blue-green and turning red-brown, 110-140 µm high asci: clavate with apical amyloid ring structure, 8-spored ascospores: simple, colorless, ellipsoid, 14-18 (-20) x 7-10 µm, smooth with thin epispore Spot tests: K+ yellow, C-, KC- and P- Secondary metabolites: with atranorin and two triterpenes. Substrate and ecology: usually on bark of conifers, rarely found on alders and rocks World distribution: Pacific North America from California to British Columbia Sonoran distribution: Santa Catalina Island in the Channel Islands of southern California. Notes: Due to its bluish gray, pruinose thallus, it may be confused with small specimens of Pannaria malmei, a species found locally in central California as well as Central and South America. However, that Pannaria does not contain atranorin, its hymenium does not turn red-brown with I, and it lacks an apical ring structure in its asci.