Thallus: areolate to subsquamulose, scattered to crowded to pulvinate, variable but often with very small lobate areoles (lion claws) areoles: flat to convex, almost granular to irregular and somewhat incised to form minute and indistinct lobes up to c. 0.5 mm long surface: green yellow to orange yellow, smooth to uneven cortex: pseudoparenchymatous, 7-15 µm thick Apothecia: common, lecanorine, 0.35-1.0 mm wide disc: darker yellow than the thallus, round, flat to somewhat convex with age margin: thin to thick, entire to crenulate, persistent exciple: often visible from the outside, thin to thick epihymenium: yellow-brown hymenium: hyaline, 55-75 µm tall; paraphyses: simple or sparingly branched apically, cylindrical or with weakly swollen tips, up to 3.5 µm wide; hypothecium: hyaline asci: clavate, 16-24-spored ascospores: hyaline, simple to 1-septate, oblong to ellipsoid, 8-12 x 3.5-5 Pycnidia: sparse, appear as darker yellow spots on the thallus conidia: hyaline, oblong to ellipsoid, 2.5-3 x 1.2-1.5 µm Spot tests: K+ reddish, KC-, C- Secondary metabolites: calycin, pulvinic acid, pulvinic dilactone and vulpinic acid. Substrate and ecology: on calcium free rocks, wood and bark World distribution: world-wide Sonoran distribution: common outside the deserts, mainly on rocks in open montane and coastal habitats in southern California, Arizona and Baja Califormia, up to at least 3500 m. Notes: Candelariella vitellina is a common and widespread species. Its thallus is rather variable in size and shape but is generally a miniature of C. rosulans in appearance. Its visible exciple is usually a distinguishing character between the two. Compared to C. lutella, it is mostly much larger and forms thicker and more conspicuous thalli.