Life habit: lichenized Thallus: little or none or immersed, crustose, continuous, without elongated lobes; prothallus: absent. 1-2 tip cells slightly swollen, with few branches; subhymenium hyaline. surface: white, without asexual propagules Apothecia: adnate, 0.2-0.4(-0.5) mm in diam., lecanorine disc: orange, flat or slightly convex margin: persistent, flush thalline margin absent; proper margin visible, concolorous with disc parathecium: irregular hyphae; exciple below hypothecium amorphous epihymenium: golden, K+ red, C- hymenium: hyaline, 70-85 µm tall asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 12.5-14(-18) x 4-5.5(-7) µm , isthmus 1-1.5(-2) µm, spore end wall thin Pycnidia: not observed Spot tests: thallus K- or K+ red Secondary metabolites: unidentified anthraquinones. Substrate and ecology: on calcareous rocks World distribution: northern Mexico Sonoran distribution: southern California, Baja California, and Baja California Sur. Notes: Caloplaca nashii has an immersed thallus, small apothecia, and occurs on calcareous rocks. Caloplaca crenulatella has small apothecia but the spores are larger.