Life habit: lichenicolous Thallus: little or none, without asexual propagules Apothecia: adnate, 0.3-0.7(-1) mm in diam., lecanorine disc: red or orange or brown, flat, epruinose margin: persistent, flush; thalline margin present, concolorous with thallus; proper margin not visible parathecium: cellular (paraplectenchymatous); exciple below hypothecium prosoplectenchymatous epihymenium: golden, K+ red, H-, 10%N-, cN-, C- hymenium: hyaline, 70-85 µm tall paraphyses: 1-2 tip cells slightly swollen, with some branching; subhymenium hyaline asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 11-14 x 5.5-7 µm, isthmus 3-4 µm, spore end wall thin Pycnidia: not observed Spot tests: apothecial margin K-, H-, 10% N-, red brown to violet, C-; thallus K-, H-, 10%N-, cN-, C- Secondary metabolites: unidentified anthraquinones. Substrate and ecology: on Candelariella over non-calcareous rock World distribution: Europe and North America Sonoran distribution: central Arizona. Notes: Caloplaca grimmiae is found only on Candelariella and has a distinctly brown to dark brown apothecial margin. It is very close to Caloplaca congrediens. The main difference is that the latter species has more thallus and is not parasitic. Caloplaca epithallina also is similar but it has a reddish margin (K+ red) and grows on many different lichens.