Life habit: lichenized Thallus: crustose, areolate, margin abrupt at edge, without elongated lobes; prothallus: absent surface: gray to blue-gray, smooth, without asexual propagules cortex: cellular, thick, without granules Apothecia: adnate to stipitate, 0.4-0.8 mm in diam., lecanorine disc: black, flat, epruinose margin: persistent, flush; thalline margin present, concolorous with thallus: proper margin not visible or visible, concolorous with disc parathecium: cellular (paraplectenchymatous) including exciple below hypothecium epihymenium: brown, K+ violet, H+ violet, 10%N + violet, cN+ violet, C+ violet hymenium: hyaline, 70-115 µm tall paraphyses: 2-3 tip cells slightly swollen, not branched or with few branches; subhymenium hyaline asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 14-18 µm x 7-10 µm, isthmus 1.5-4 µm, spore end wall thin Pycnidia: not observed Spot tests: apothecial margin K+ violet, H+ violet, 10% N+ violet, cN+ violet, C+ violet; thallus K+ violet, H+ violet, 10%N+ violet, cN+ violet, C+ violet Secondary metabolites: unidentified anthraquinones and thalloidima green. Substrate and ecology: on non-calcareous or calcareous rocks World distribution: western North America Sonoran distribution: southern California and Arizona. Notes: Caloplaca albovariegata is distinguished by the blue-gray thallus color, the stipitate areoles, thick irregular thallus cortex with algae in clumps, and the thick necral layer. The thallus thickness is somewhat variable and in some cases approaches C. atroalba but that has a thallus cortex with little or no necral layer and a continuous algal layer. In rock depressions C. albovariegata is more stipitate and in some places subsquamulose. Caloplaca peliophylla is similar but that has lighter brown discs and the spore isthmus is narrower.