Life habit: lichenized Thallus: crustose, elongate lobed, margin abrupt at edge, with elongated lobes 1-2 mm long, 0.3-1 mm wide; prothallus: absent surface: orange, smooth, without asexual propagules cortex: cellular, 15-50 µm thick, granules absent, medulla prosoplectenchymatous or dense, without granules Apothecia: immersed or adnate, 0.4-1 mm in diam., lecanorine disc: orange, flat, epruinose margin: persistent, flush or slightly raised; thalline margin present, concolorous with thallus; proper margin not visible or visible, concolorous with disc parathecium: cellular (paraplectenchymatous); exciple below hypothecium amorphous epihymenium: golden, K+ red, H-, 10%N-, cN-, C- hymenium: hyaline, 70-85 µm tall paraphyses: 2-3 tip cells swollen, not branched; subhymenium hyaline asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 11-14 x 5.5-7 µm, isthmus 2-4 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, and teloschistin. Substrate and ecology: on non-calcareous or calcareous rocks World distribution: worldwide Sonoran distribution: southern California, Arizona, Baja California, and Baja California Sur. Notes: Caloplaca saxicola has a small thallus with short lobes that sometimes look inflated with apothecia developing near tips of lobes. It is similar to C. ignea and C. impolita but they have larger thalli with apothecia developing near the center of the thallus.