Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2007. Lichen Flora of the Greater Sonoran Desert Region. Vol 3.

Life habit: lichenized Thallus: crustose, elongate lobed, margin abrupt at edge, with elongated lobes 0.7-3 mm long, 0.3-0.8 mm wide; prothallus: absent surface: red to orange, smooth, without asexual propagules cortex: cellular, 21-35 µm thick, granules absent; medulla prosoplectenchymatous, without granules Apothecia: adnate or stipitate, 0.3-1 mm in diam., lecanorine disc: red or orange, flat, epruinose margin: persistent, slightly raised; thalline margin present, concolorous with thallus; proper margin visible, concolorous with disc parathecium: cellular (paraplectenchymatous) including exciple below hypothecium epihymenium: golden, K+ red, H-, 10%N-, cN-, C- hymenium: hyaline, 60-70 µm tall paraphyses: 2-3 tip cells swollen, with few branches; subhymenium hyaline asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 11-12.5 x 5.5-7 µm, isthmus 2-3 µm, spore end wall thin Pycnidia: present, totally immersed, ostiole orange Spot tests: apothecial margin K+ red, H-, 10% N-, cN-, C-; thallus K+ red, H-, 10%N-, cN-, C-; medulla IKI- Secondary metabolites: parietin, fallacinal, emodin, teloschistin, and parietinic acid. Substrate and ecology: on non-calcareous rocks or occasionally on calcareous rocks World distribution: western North America Sonoran distribution: southern California, Baja California, and Baja California Sur. Notes: Caloplaca ignea is usually very distinctive with its bright reddish color and the convex lobes. Caloplaca impolita has orange broadening lobes that are frequently pruinose. Caloplaca saxicola that has shorter orange lobes and is mainly found inland.