Life habit: lichenized Thallus: crustose, elongate lobed, margin abrupt at edge, with elongated lobes, 1.5-6 mm long, 0.5-1.5 mm wide; prothallus: absent surface: orange, verruculose; asexual propagules absent cortex: amorphous, 30-70 µm thick, with granules insoluble in K; medulla dense, without granules Apothecia: adnate, 0.5-1 mm, lecanorine disc: orange, flat, epruinose margin: persistent, flush; thalline margin present, concolorous with thallus; proper margin not visible parathecium: cellular (paraplectenchymatous) including exciple below hypothecium epihymenium: golden, K+ red, H-, 10%N-, cN-, C- hymenium: hyaline, 70-90 µm tall paraphyses: 2-4, tip cells swollen, with few branches or with some branching; subhymenium hyaline asci: cylindrical, 8-spored ascospores: hyaline, 2 locules, ellipsoid, 11-15.5 x 5.5-7 µm, isthmus 3-3.5 µm, spore end wall thin Pycnidia: not observed 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 or calcareous rocks World distribution: Europe, North America, and northern Asia Sonoran distribution: Arizona. Notes: Caloplaca trachyphylla has a large thallus composed of verruculose rather rough convex lobes with a dense non-paraplectenchymatous thallus cortex. It is similar to Xanthoria elegans but that species is uplifted from the substrate, has a paraplectenchymatous upper cortex and a lower cortex. Caloplaca saxicola has a much smaller thallus without verruculose lobes.