Life habit: lichenized Thallus: crustose, areolate, without elongated lobes; prothallus: present, black surface: gray, smooth, without asexual propagules Apothecia: adnate, 0.3-0.8 mm in diam., lecideine disc: dark reddish orange, flat, epruinose margin: persistent, flush; thalline margin absent; proper margin visible, concolorous with disc or little lighter than disc parathecium: consisting of radiating hyphae, exciple below hypothecium amorphous epihymenium: golden, K+ red hymenium: hyaline, (60-)70-100 µm tall paraphyses: 2-3 tip cells slightly swollen, with some branching; subhymenium hyaline asci: cylindrical, 8 spores ascospores: hyaline, 2 locules, ellipsoid, 12.517 x (5.5-)7-10 µm, isthmus 4-7(-8.5) µm, spore end wall thin Pycnidia: not observed Spot tests: apothecial margin C+ red; thallus K-, C+ red Secondary metabolites: parietin, fallacinal, emodin, and teloschistin. Substrate and ecology: on wood or bark World distribution: worldwide Sonoran distribution: southern California, Arizona, Baja California Sur, western Chihuahua, Sonora, and northern Sinaloa. Notes: Caloplaca ferruginea is restricted to bark and wood and has dark red-brown apothecia that usually lack algae. The hypothecium usually has abundant oil. Caloplaca catalinae is similar but has smaller spores.