Life habit: lichenized Thallus: crustose, areolate, without elongated lobes; prothallus: absent surface: gray, verruculose or pruinose, without asexual propagules Apothecia: adnate, 0.3-0.5 mm in diam., lecanorine disc: orange, flat, epruinose or pruinose margin: persistent, flush; thalline margin present or absent, concolorous with thallus; proper margin visible, concolorous with disc parathecium: elongate to oval cells; exciple below hypothecium cellular (paraplectenchymatous) epihymenium: golden, K+ red, C- hymenium: hyaline, 63-84 µm tall paraphyses: 1-2 tip cells swollen, with few branches; subhymenium hyaline asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 10-12.5(-14) x 4-7 µm, isthmus 4.2-5.5 µm, spore end wall thin Pycnidia: present, mostly immersed, ostiole orange Spot tests: apothecial margin K-, C-; thallus K-, C- Secondary metabolites: parietin, fallacinal, emodin, and teloschistin. Substrate and ecology: on wood or bark World distribution: southwestern North America Sonoran distribution: southern California, Baja California, and Baja California Sur. Notes: Caloplaca stanfordensis is a member of the holocarpa group and is characterized by the light gray or tan margins and the completely gray thallus. It is quite variable along its range north to south. In the northern part of its range the apothecia are not pruinose and the margins are smooth but toward the south both the pruina on the discs and the roughness of the margins increase. It has often been called C. cerina but that species has dark gray apothecial margins that react K+ violet. The material treated here under C. holocarpa always has some orange color associated with the thallus.