Thallus: umbilicate, mono- or polyphyllous (sometimes lobate), +circular to irregular in shape, thin, brittle, 1-4(9) cm in diam. upper surface: brown, smooth where not patchily covered with granular to coralloid, or club- to leaf-like isidia lower surface: light to dark brown or black, smooth to occasionally broadly pitted Apothecia: rare, black, sessile to stipitate, gyrose, up to 1.5 mm in diam. asci: clavate, 8-spored ascospores: hyaline, simple, broadly ellipsoid, 6-12 x 4-8 µm Spot tests: medulla K-, C+ red, KC+ red, P- Secondary metabolites: gyrophoric, lecanoric and hiascic acids. Substrate and ecology: on siliceous rocks, boreal to low alpine vegetation zones, usually under the snow in winter World distribution: Europe, Asia, North and South America Sonoran distribution: in montane habitats in moister microhabitats of Arizona. Notes: Among the Sonoran Umbilicariae, Umbilicaria deusta is the only one that reproduces by isidia, found on the upper surface.