Thallus: rimose-areolate; areoles: 0.4-1.8 mm in diam., plane, thin; upper surface: grayish brown to brown, smooth, shiny or dull, epruinose; Ascomata: perithecioid, immersed, up to 2.5 mm in diam.; disc: blackish, plane; proper exciple: up to 70 µm thick; hymenium: 100-130 µm high; asci: cylindrical to subclavate, 4-6-spored; ascospores: brown, muriform, broadly ellipsoid, 16-26 x 8-18 µm; transverse septa 4-6, longitudinal septa 1-3 per transverse segment; Pycnidia: not seen; Spot tests: K-, C+ red, KC-, P-, UV-; Secondary metabolites: lecanoric acid (major) and orsellinic acid (minor).; Substrate and ecology: on siliceous rocks; World distribution: North and South America, southwestern Europe, and East Asia; Sonoran distribution: scattered in southern California and Arizona, Baja California (Guadalupe Island, Baja California Sur, Chihuahua and Sonora, occurring in mountainous regions at 270 to 2240 m.; Notes: Diploschistes aeneus has perithecioid ascomata, a brownish thallus, contains lecanoric acid, and has broadly ellipsoid spores. It may be confused with D. badius, a species that also has a brownish thallus, but can be distinguished by the presence of gyrophoric acid and the thicker thallus.