Life habit: lichenized Thallus: crustose, elongate lobed, lobes 0.5-2.5 mm long, 0.2-0.4 mm wide; prothallus: present or absent, yellowish surface: orange, smooth, without asexual propagules cortex: adglutinate hyphae, 20-70 µm thick; medulla dense, without granules Apothecia: adnate, 0.3-0.7 mm in diam., lecanorine disc: orange, flat, epruinose margin: persistent, flush; thalline margin present, concolorous with thallus; proper margin visible, concolorous with disc parathecium: consisting of radiating hyphae; exciple below hypothecium amorphous epihymenium: golden, K+ red, H-, 10%N-, cN-, C- hymenium: hyaline, 60-75 µm tall paraphyses: 2-3 tip cells swollen, with few branches; subhymenium hyaline asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 11-4 x 4-.5 µm, isthmus 2-3 µm, spore end wall thin Pycnidia: present, totally immersed, ostiole orange Spot tests: apothecial margin K+ red, H-, 10% N-, cN-, C-; thallus K+ red, H-, 10%N-, cN-, C-; medulla IKI- Secondary metabolites: parietin, fallacinal, emodin, teloschistin, and parietinic acid. Substrate and ecology: on non-calcareous rocks World distribution: western North America Sonoran distribution: southern California and Baja California. Notes: Caloplaca brattiae is characterized by the yellowish orange thalli with distinct rather short, strongly convex marginal lobes and the thallus cortex composed of anticlinal hyphae. The central parts of the thallus usually have numerous apothecia. Other similar species which occur within the range of C. brattiae are C. ignea which has longer, broader and redder lobes and C. impolita with lobes that broaden at the tips and are frequently pruinose.