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, areolate, without elongated lobes; prothallus: absent surface: gray or blue-gray, verruculose, isidiate or lobulate isidia: granular Apothecia: adnate, 0.4-0.8 mm in diam., lecanorine disc: dark reddish orange, flat or slightly convex, epruinose margin: persistent, flush or slightly raised; thalline margin present or absent, concolorous with thallus; proper margin visible, concolorous with disc parathecium: irregular hyphae or elongate to oval cells; exciple below hypothecium amorphous epihymenium: golden, K+ red, C- hymenium: hyaline, 70-75 µm tall paraphyses: 1-2 tip cells slightly swollen, with few branches; subhymenium hyaline asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 11-14 x 5.5-7 µm, isthmus 3.5-4 µm, spore end wall thin Pycnidia: present, totally immersed, ostiole red Spot tests: apothecial margin K-, H-, 10% N-, cN-, C+ red to C+ violet; thallus K-, H-, 10%N-, C- Secondary metabolites: parietin and emodin. Substrate and ecology: wood or bark World distribution: North America and Europe Sonoran distribution: widely distributed in Arizona. Notes: Caloplaca furfuracea has a dark gray thallus and the apothecia are dark red-brown. The distinguishing characters of this species are the granular isidia, the usually dark thallus (never orange), and the presence of a gray thalline margin on some apothecia. The apothecia are similar in color to C. ferruginea but that has a wider spore isthmus and no isidia. The apothecia of the C. chlorina are orange but the thallus may appear similar to this species when on bark and wood.