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: little or none, crustose, areolate, without elongated lobes; prothallus: absent surface: orange or gray, smooth, without asexual propagules Apothecia: adnate, 0.3-0.7 mm, lecanorine disc: orange, flat, epruinose margin: persistent, flush; thalline margin present, concolorous with thallus; proper margin visible, little lighter than disc parathecium: elongate to oval cells; exciple below hypothecium amorphous or cellular (paraplectenchymatous) epihymenium: golden, K+ red, C- hymenium: hyaline 60-85 µm tall paraphyses: 1-2 tip cells slightly swollen or swollen, not branched or with few branches; subhymenium hyaline asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 10-14 x 5.5-7 µm, isthmus 1.5-4(-5.5) µm, spore end wall thin Pycnidia: present, mostly immersed, ostiole orange Spot tests: apothecial margin K+ red, C-; thallus K- or K+ red Secondary metabolites: parietin, fallacinal, emodin, and teloschistin. Substrate and ecology: on wood or bark World distribution: worldwide Sonoran distribution: southern California, Arizona, Baja California and Baja California Sur. Notes: This treatment of the Caloplaca holocarpa group is very tentative. As treated here this species is restricted to bark and wood and usually has some orange margin on the lower parts of the apothecia and orange places on the gray thallus that may be apothecial initials. The thallus is often scant and some collections have a little thalline margin at the base of the apothecia. The apothecia are usually small and the margins are about the color of the discs. Caloplaca stanfordensis is probably in this group but that has no orange color in the thallus. Hoffman in the original description described the thallus as "aurantia" while Acharius in his description of pyracea described the thallus as "cinereascente". Only examination of the types will determine whether they are synonyms. The species on calcareous rocks under C. holocarpa all seem to be C. crenulatella while the material on non-calcareous rocks are another species.