Thallus: crustose, forming a thick, +continuous crust, rarely cracked, not forming areoles; prothallus: absent surface: yellowish white to yellowish gray, rugose to granulose-isidiate, epruinose, with a distinct margin, esorediate Apothecia: lecanorine, adnate to +immersed, 1.5-2.5 mm in diam. disc: light orange, pruinose-scabrose, K-, C+ red, KC-, P- margin: concolorous with thallus surface, verruculose, flexuose, distinctly double, sometimes smooth to disc and rough outside, cortex K-, C-, KC-, P- amphithecium: medulla: white, thick; algal layer: thick and continuous or in scattered clumps below hypothecium; cortex: thin, not distinct laterally, becoming thick and gelatinous below exciple: not distinct hymenium: 160-175 µm tall; hypothecium: not differentiated, up to 125 µm thick asci: 8-spored ascospores: hyaline, simple, ellipsoid, 25-38 x 14-18 µm Pycnidia: not seen Spot tests: thallus K-, C-, KC-, P-, UV-; medulla K-, C+ red, KC+ red, P- Secondary metabolites: thallus and apothecia with gyrophoric, lecanoric and variolaric acids. Substrate and ecology: on wood and bark of Pinus and Juniperus, rarely Quercus, in Juniperus-Pinus edulis woodlands, at 1500-2500 m World distribution: Texas and Arizona Sonoran distribution: central and southern Arizona and Chihuahua. Notes: Ochrolechia subisidiata is the only granuloseisidiate Ochrolechia species in the Sonoran region. It differs from other members of the parella-group (those having correlating characters of variolaric acid production and pruinose-scabrose apothecia, including O. pseudopallescens) by having gyrophoric acid in the medulla of the thallus and apothecial margins.