Thallus: squamulose squamules: scattered to adjacent, not overlapping, 0.5-1 mm wide, 0.1-0.25 mm thick, plane, broadly adnate with only the very edges slightly elevated, incised surface: brown, smooth, often with darker rims upper cortex: 10-30 µm thick, composed of angular cells (5-9 µm in diam.) medulla: composed of spherical cells 5-9 µm wide with small air spaces between them; algal layer: 30-60 µm high; algal cells: 6-10 µm in diam. lower cortex: not delimited, composed of more closely packed medullary cells whose walls darken below; rhizohyphae: hyaline to faintly brownish, 2.5-3.5 µm thick lower surface: pale brown to blackish Perithecia: broadly pyriform, up to 0.25 mm wide; apex: concolorous with or paler than the thallus; exciple: dark brown to black, c. 20 µm thick; periphyses: c. 25-35 µm long; hymenial algal cells: (sub)globose, 2.5-3.5 µm in diam. asci: clavate, c. 70 x 17 µm, 2-spored ascospores: muriform, ellipsoid, colorless to very pale brownish when overmature; the proximal and distal spores of about the same length, 25-32 x 12-16/ 25-36 x 10-13 µm Pycnidia: not seen Spot tests: all negative Secondary metabolites: none detected. Substrate and ecology: on siliceous rock in dry and sun-exposed situations World distribution: Japan and SW North America Sonoran distribution: Arizona, California (Channel Islands) Chihuahua and Sonora. Notes: The distinction from E. pallidulum may be difficult (see under that species).