Habit: lichenized Thallus: squamulose, adpressed to ascending, sometimes ±bullate centrally (almost fruticose, isidia-like) squamules: up to 1.8 mm long, crenate, with a pseudocortex 5-15 µm thick composed of non-gelatinized hyphae with ±isodiametric cells 3-6 µm wide surface: mustard yellow to greenish yellow, smooth lower cortex: 15-40 µm thick, composed of gelatinized hyphae with ±isodiametric cells 4-7 µm wide Apothecia: common, lecanorine, rounded, 0.6-1.7(-2.6) mm wide disc: darker yellow than the thallus, plane to slightly convex; margin: persistent to partially excluded, even to flexuose, sometimes crenulate, exciple: indistinct, composed of radiating hyphae with ±rectangular cells epihymenium: reddish yellow to yellow-brown hymenium: hyaline, 75-105 µm tall; paraphyses: simple, 1.5-2 µm wide medially, with tips expanded up to 4 µm wide asci: narrowly clavate, 50-85 x 16-20 µm, 8-spored ascospores: hyaline, simple, acicular, rarely straight, usually strongly curved, becoming S-shaped, thickening at one end, (30.5-)34.5-48(-57) x 3-4(-5) µm Pycnidia: common, lobed, immersed, appearing as darker yellow warts on the thallus surface conidia: oblong, 3.5-4.5 x c. 1.5 µm Spot tests: K+ pale red, KC-, C- Secondary metabolites: calycin, pulvic acid lactone, vulpinic and pulvinic acids. Substrate and ecology: on acidic rocks and sometimes on soil or mosses in seepage areas, in montane habitats up to 2800 m World distribution: western North America (Colorado, Montana and Utah) Sonoran distribution: not currently know from the region but expected at least in NE Arizona due to its proximity to known sites within a few km of the Arizona border (e.g. Mesa Verde in the SW corner of Colorado). Notes: The long, somewhat asymmetrical acicular spores of C. spraguei are unique within Candelariella. Superficially, it can be recognized by its large, yellow, rosulate to subfruticose thallus that often has a greenish tinge.