Description

 Thallus: foliose, single lobed attached by a single umbilicus and with 14-60 mm wide lobes; upper surface: gray, with epinecral layer consisting of air filled hyphae; upper cortex: 130-240 µm thick with the outermost 10-20 µm brown; medulla: 180-350 µm thick; lower cortex: 90-110 µm thick with the outermost 15-40 µm brown, the lower cortex cells are angular and in distinct vertical columns, uneven lower surface were 2-4 cell rows thick outgrowths cause the farinose lower surface of the species; lower surface: brown, farinose and often reticulate, occasionally with rhizinomorphs; Perithecia: obpyriform to almost globose, 200-530 x 170-440 µm, primarily with a hyaline exciple that is light brown to brown in the uppermost part, rarely hyaline throughout; asci: clavate or cylindrical, 8spored; ascospores: simple, hyaline, 12-17 x 5-9 µm; Pycnidia: not found in Sonoran material, elsewhere immersed, ostiolum similar to that of the perithecium; conidia: bacilliform, 4-6 x 1 µm; Spot tests: all negative; Secondary metabolites: none detected.; Substrate and ecology: on different rock-types, often on boulders and occasionally in seepages; World distribution: western North America; Sonoran distribution: throughout Arizona and southern California.; Notes: Dermatocarpon reticulatum is unique in the genus in having farinose lower surface which often also is reticulate.