Life habit: lichenized Thallus: crustose, areolate to sub-squamulose, margin slightly lobed or notched, without elongated lobes; prothallus: absent surface: color yellowish orange, smooth, without asexual propagules cortex: adglutinate hyphae, 45-145 µm thick, granules absent; medulla without granules Apothecia: adnate, 0.5-1.5 mm in diam., lecanorine disc: brownish orange, flat or convex, epruinose margin: disappearing; 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, 77-85 µm tall; tip cells not swollen, with some branching or frequently branched; subhymenium hyaline asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 15.5-19.5 x 5.5-7 µm, isthmus 1.5-3 µm, spore end wall thin Pycnidia: present, ostiole red or orange Spot tests: apothecial margin K+ red; thallus K+ red Secondary metabolites: parietin, fallacinal, emodin, and xanthorin. Substrate and ecology: on non-calcareous rocks World distribution: coastal western North America Sonoran distribution: southern California and Baja California. Notes: Caloplaca stantonii has a subsquamulose yellow-orange thallus that sometimes develops soredia-like granules on the margin and has a dense non-paraplectenchymatous cortex. The apothecia are dark red-brown. Caloplaca bolacina has bullate or convex smooth areoles that may become subsquamulose and also has a similar dense cortex but has lighter orange apothecia. Caloplaca luteominia has less thallus and a paraplectenchymatous cortex.