Life habit: lichenized Thallus: squamulose, subsquamulose, without elongated lobes; prothallus: absent surface: orange to yellowish-orange, smooth, sorediate or phyllidiate soredia: if present granular in irregular, marginal soralia cortex: cellular, 15-50 µm thick, granules absent; medulla paraplectenchymatous, without granules Apothecia: adnate, 0.3-0.8 mm in diam., lecanorine disc: orange, flat, epruinose margin: persistent, slightly raised; thalline margin present or absent, concolorous with thallus; proper margin visible, concolorous with disc parathecium: cellular (paraplectenchymatous) including exciple below hypothecium epihymenium: golden, present, K+ red, 10%N-, cN-, C- hymenium: hyaline, 60-80 µm tall paraphyses: 3-5 tip cells swollen, not branched; subhymenium hyaline asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 11-14 x 5.5-7 µm, isthmus 3-4 µm, spore end wall thin Pycnidia: present, mostly immersed, ostiole orange Spot tests: apothecial margin K+ red, 10% N-, cN-; thallus K+ red, 10%N-, cN-; medulla IKI- Secondary metabolites: unidentified anthraquinones. Substrate and ecology: on non-calcareous rocks or occasionally on calcareous rocks World distribution: southwestern North America and northern Mexico Sonoran distribution: Arizona, Baja California Sur, and Sonora. Notes: Caloplaca phyllidizans has an areolate to subsquamulose thallus with some of the marginal areoles becoming elongated into short lobes. The marginal phyllidia originate as corticate outgrowths on the margins of the areoles and then often develop into soredia. The soredia sometimes are tinged bluish, similar to those of Caloplaca xanthostigmoidea This member of the C. squamosa group is distinct in its production of propagules on the areole margins.