Thallus: epilithic, effuse, verrucose-areolate, up to 5 cm in diam. verrucae: irregular, hemispheric or conic, 1-1.4 mm in diam. and up to 1.5 mm high surface: cervine brown, covered by a cracked hyaline layer 17-34 µm thick cortex: 11-23 µm thick, consisting of hyaline, narrow, intricately interwoven hyphae, that at the surface are covered by a 4-5 µm thick layer of dark brown, sclerotized hyphal apices rendering the thallus its brown color algal layer: irregular, 150-200 µm thick, interrupted by strands of cortical hyphae penetrating deep into the thallus Apothecia: 1(-3) per verruca disc: black, epruinose, 0.7-1.1 mm in diam., at first immersed, soon becoming partly extruded exciple: black, 17-28 µm thick at the base adjacent to the hypothecium, widened towards the top and there 65-95 µm thick and forming a collar projecting slightly above the surface of the thallus surrounding the mazaedium hypothecium: merged at the base with exciple, 110170 µm high, dark brown, strongly intertwined hyphae hymenium: paraphyses: 1.5 µm wide, slightly branched above asci: rupturing early, 35-55 x 3-4 µm, with uni-to biseriately arranged spores ascospores: brown, 1-septate and constricted in the middle, ellipsoid, 11-16 x 7-10 µm, with an ornamentation of mainly longitudinally arranged, minute ridges in young spores, that during the maturation of the spore are disrupted by a few irregular cracks Spot tests: thallus K+ rusty crystals, C-, KC-, P+ orange Secondary metabolites: thallus with norstictic acid. Substrate and ecology: on rock World and Sonoran distributions: coast of southern California to Baja California. Notes: Cyphelium brunneum is characterized by its brown thallus and immersed apothecia and is unique among Sonoran species in occurring on rock.