Life habit: lichenized Thallus: crustose, continuous or areolate, margin thinning at edge, without elongated lobes; prothallus: absent surface: yellowish orange, pruinose, sorediate soredia: fine, in delimited, laminal, irregular or round soralia cortex: cellular, 20-35 µm thick, granules absent; medulla without granules Apothecia: adnate, 0.4-0.8 mm in diam., lecanorine disc: dark reddish orange, flat, epruinose margin: persistent, flush; thalline margin absent; proper margin visible, concolorous with disc parathecium: consisting of radiating hyphae, exciple below hypothecium irregular hyphae epihymenium: golden, K+ red hymenium: hyaline, 60-70(-85) µm tall; tip cells not swollen, with some branching; subhymenium hyaline asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 11-15.5 x 5.5-7(-8.5) µm, isthmus (1.5-)3-4(-5.5) µm, spore end wall thin Pycnidia: present, mostly immersed, ostiole orange Spot tests: thallus K+ red, C+ red Secondary metabolites: unidentified anthraquinones. Substrate and ecology: on wood or bark World distribution: western North America Sonoran distribution: southern California, Arizona, Baja California Sur, western Chihuahua, Sonora and northern Sinaloa. Notes: Caloplaca persimilis has a tan to greenish orange areolate thallus that originates under the surface of the substrate, the soredia are tan-orange, and the apothecia are brownish-orange and lack a thalline margin. The soredia are in mounds and similar in color to the thallus. Caloplaca microphyllina has a dark orange subsquamulose thallus and red-orange apothecia.