Thallus: thin or thick, continuous, plane or more usually rugose, sometimes becoming subsquamulose surface: gray-brown or reddish brown, dull; margin: indeterminate; prothallus: lacking; vegetative propagules: absent Apothecia: adnate, frequent and often contiguous, up to 0.75-1.5 mm in diam. disc: dark brown, more commonly black, sometimes pruinose especially when young, quickly becoming convex thalline margin: 0.05-1 mm wide, entire, often becoming excluded; excipular ring: absent thalline exciple: 40-120 µm wide laterally; cortex: 10-20 µm wide; cells: up to 5.5-6.5 µm in diam. not pigmented, irregular and often not distinct; algal cells: up to 11-17 µm in diam. proper exciple: sometimes light brown, 15-30 µm wide laterally, expanding to 25-50 µm at periphery hymenium: 115-170 µm tall; paraphyses: 2-2.5 µm wide, not conglutinate, with apices up to 4-5 µm in diam., pigmented light brown and suffused in brown pigment to form a light brown epihymenium; hypothecium: hyaline or pale brown in specimens with dark thalli, 60-145 µm thick, inspersed with oil droplets asci: clavate, 80-100 x 16-29 µm, 8-spored ascospores: brown, 1-septate, ellipsoid, type A development, Physcia-type, (22-)27.5-29.5(-35) x (10.5-)13-14(-16.5) µm, usually retaining thick apical wall, cells often unequal in size from early development; torus: prominent walls: not ornamented Pycnidia: immersed in thallus conidia: bacilliform, 4-5 x c. 1 µm Spot tests: all negative Secondary metabolites: variolaric acid present or absent. Substrate and ecology: on moss in arctic-alpine habitats from sea level in the arctic to 4070 m in the southern part of its range in North America World distribution: frequent in arctic-alpine regions across the Northern Hemisphere Sonoran distribution: restricted to Coconino County, Arizona at elevations of 2470-4070 m, the southern limit of its range. Notes: Rinodina mniaraea is the only arctic-alpine representative of the genus in the study area and is well characterized by its muscicolous substrate, continuous thallus, convex apothecia and large, Physciatype spores. Two chemotypes, scattered elsewhere in its range, have been recognized by Mayrhofer and Moberg (2002) and should be sought. The var. cinnamomea Th. Fr. has a yellow to orange medulla (K+ purple, skyrin) and the var. mniaraieza (Nyl.) H. Magn. has a light gray thallus (K+ yellow, atranorin in the cortex). Rinodina turfacea (Wahlenb.) Körb., another arctic-alpine species that comes as far south as Colorado, is distinguished by its sessile apothecia, with persistently plane discs, expanded and columnar lower cortex, and the presence of sphaerophorin.