Thallus: crustose, of deeply cracked areolate to subsquamulose areoles: strongly convex, 0.3-0.7 mm thick, from contiguous to dispersed, similar whether sterile or fertile surface: dark brown or blackish brown; smooth prothallus: absent Perithecia: within larger areoles, only mouth showing with part of involucrellum which is thickened only near mouth (subcompound), black or dark brown, merging with thallus tissue; exciple: hyaline to pale brown, blackening toward mouth asci: saccate, 2-spored ascospores: ellipsoid or ovoid, dark brown, muriform with many cells, 20-50 x 15-25 µm Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on acid or basic rocks often near but not in water World distribution: circumpolar temperate and boreal; western montane specimens range up to 3600 m and extending to central Mexico Sonoran distribution: common in Arizona and scattered in southern California and Sonora where limestone occurs and on gneiss, schist and sandstone.