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

Thallus: crustose areoles: up to 0.5 (-1.0) mm diam., adnate, weakly convex upper surface: light gray or yellowish brown, dull soredia: yellowish brown, diffuse upper cortex: up to 15 µm thick, composed of thin-walled hyphae Apothecia: up to 0.6 (-0.8) mm diam., marginal or laminal, plane; disc: black, epruinose, egyrose; margin: remaining prominent, entire or flexuose; exciple: composed of closely conglutinated hyphae, brown in inner part, brownish black in the rim, not containing crystals, K+ violet, N-; hypothecium: dark brown; epithecium: dark brown, not containing crystals, K+ violet, N-; paraphyses: without swelling or pigment cap in apical cell asci: with a well developed tholus containing an amyloid flank ascospores: broadly to narrowly ellipsoid, simple, 6-9 x 2.5-4.5 µm Pycnidia: sessile, black, attached to the areole or apparently directly to the substrate conidia: ellipsoid to shortly bacilliform, 3.5-5 x 1.5-2.5 µm Spot tests: upper cortex and medulla K+ yellow, C+ red, KC+ red, P+ yellow Secondary metabolite: alectorialic acid. Substrate and ecology: on wood (elsewhere also bark) of conifers, not charred, in conifer forests at 2750-3400 m alt. World distribution: Europe and North America Sonoran distribution: Arizona and Chihuahua, rare. Notes: The species may be regarded as the sorediate counterpart of H. praestabilis.