Thallus: crustose, evanescent or thin, of discrete verrucae, up to 0.15-0.25 mm wide, becoming contiguous and continuous or rimose, plane or more usually rugose surface: dark gray to red-brown, dull; margin: determinate or indeterminate; prothallus: lacking; vegetative propagules: absent Apothecia: sessile or adnate, frequent, sometimes contiguous, dispersed on smooth bark, up to 0.4-0.6 mm in diam. disc: dark brown (especially when wet), sometimes becoming black, persistently plane thalline margin: concolorous with thallus, 0.05-0.1 mm wide, entire, sometimes becoming flexuose, persistent; excipular ring: visible in gray thalli, confluent thalline exciple: 50-70 µm wide laterally; cortex: 5-10 µm wide; epinecral layer: 5 µm wide, rarely present; cortical cells: up to 5-7.5 µm wide, pigmented; algal cells: up to 14-18 µm in diam.; thalline exciple: 70-100 µm wide below; cortex 5-15 µm wide, also cellular proper exciple: 5-10 µm wide laterally, expanding to 15-30 µm at periphery hymenium: 60-80 µm tall; paraphyses: 2-3 µm wide, conglutinate, with apices up to 4-5 µm wide, lightly pigmented, usually immersed in dispersed pigment forming a light red-brown epihymenium; hypothecium: hyaline, 30-40(-70) µm thick asci: clavate, 45-65 x 12-18 µm, 8-spored ascospores: brown, 1-septate, ellipsoid, type A development, Physcia-type, (11.5)14-15.5(-18) x (5.5-)7-8(-9.5) µm, lumina angular at first, canals mostly disappearing as lumina become rounded, apices remaining thick walled; torus: prominent at maturity; walls: not ornamented Pycnidia: not seen Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: mostly on smooth bark of deciduous trees and twigs of conifers World distribution: Europe (the Alps and Norway) and North America (Great Lakes region to northeastern seaboard states and provinces, and Rocky Mountains, southern Alberta and British Columbia to New Mexico) Sonoran distribution: Arizona in Apache and Coconino Counties, at elevations of 1740-2960 m. Notes: Rinodina glauca typically has dark, Physcia-type spores with a relatively prominent torus giving the appearance of a very dark transverse septum. The spores are reminiscent of R. boulderensis, a species that is easily distinguished by the light gray thallus with atranorin in the cortex. In the Great Lakes region, R. glauca is wholly comparable with European material examined. The western population has smaller spores and may prove to be a different species.