Life habit: lichenized Thallus: crustose, areolate to elongate lobed, margin abrupt at edge, with elongated lobes, 1.5-5 mm long, 1 mm wide, prothallus: absent surface: orange, pruinose, without asexual propagules cortex: cellular, 21-28 µm thick, with granules insoluble in K; medulla prosoplectenchymatous, with granules dissolving in K Apothecia: adnate, 0.5-1 mm in diam., lecanorine disc: dark reddish orange, flat 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 irregular hyphae epihymenium: golden, K+ red hymenium: hyaline, 60-70 µm tall paraphyses: 1-2 tip cells slightly swollen, with few branches, subhymenium hyaline asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 10-12.5 µm, 3.5-5.5 µm, isthmus c. 3 µm, spore end wall thin Pycnidia: present, mostly immersed, ostiole orange Spot tests: apothecial margin K+ red; thallus K+ red Secondary metabolites: unidentified anthraquinones. Substrate and ecology: on calcareous rocks World distribution: North America Sonoran distribution: southern California and western Chihuahua. Notes: Caloplaca eugyra is characterized by the closely appressed, thin, yellow-orange lobes that are laterally touching. A similar species not found in the area is C. galactophylla that has more convex, lobes that are not laterally touching and by apothecia reddish orange discs. Both of these species are usually white pruinose.