Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.

Thallus: crustose, often very thick (up to 5 mm) and irregularly cracked to rimose areolate, usually in discrete +orbicular thalli up to c. 12 cm wide but sometimes coalescing to form large patches over 20 cm wide, often extending over the margins of the substrate, marginally sublobate; prothallus: thin, visible between the areoles, black, frequently inconspicuous areoles: mostly contiguous and fused, 0.5-1 mm wide but up to 1.5 mm wide at the margins, irregular, angular, often warty upper surface: white or whitish gray, smooth to strongly irregular medulla: white, cretaceous; algal layer: 100-150 µm thick; algae: 8-12 µm in diam. Apothecia: sessile to irregularly substipitate to stipitate, sometimes with one side higher relative to the thallus surface than the opposite side, 1-5(-10) mm wide margin: white, lecanorine, thick, crenulate, flexuous disc: black, plane to concave or slightly convex exciple: hyaline throughout 100 to 200 µm thick, composed of hyphae, 3-5 µm in diam. epihymenium: dark red-violet to red-brown hymenium: violet-red or brown above, I+ blue, 50-100 mm tall; hypothecium: dark brown to yellow-brown, 100-200 µm thick asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid, 7-13 x 5-8 µm conidia: filiform, c. 10 x 1 µm Spot tests: upper cortex: K+ yellow, C-, KC-, P-; medulla K-, C-, KC-, P+ yellow Secondary metabolites: upper cortex with atranorin (minor) and chloroatranorin (trace); medulla with alectoronic and psoromic acids (both major) and α-collatolic and physodic acids (both trace). Substrate and ecology: on non-calciferous rocks and pebbles along the Pacific coast World and Sonoran distribution: coastal regions of southern California, Baja California and Baja California Sur.