Thallus very variable, pale grey-fawn to dark grey, usually with a fairly strong brown tinge, rimose-cracked, rarely sorediate (var. sorediata). Areoles to 600 µm diam., irregular, flat or in part uneven-convex. Prothallus dark brown or black, often mosaic-forming. Upper cortex undifferentiated, sometimes with a layer of brownish surface cells. Lower cortex absent. Photobiont chlorococcoid. Anamorph: conidiomata pycnidia, often abundant, brown, immersed to emergent with a thin, ragged thalline rim. Conidia 2.5-4.5 × ca 1 μm. Teleomorph: ascomata apothecia, to 1.5 mm diam., immersed with a cuff-like thalline margin or sessile, rounded to strongly flexuose. Disc brown-black, flat or ± convex. True exciple concolorous with or often paler than the disc, persistent or ± disappearing. Epithecium brown, well-developed. Hymenium and hypothecium hyaline. Interascal tissue of paraphyses 1.5-2 μm diam., unbranched or sparsely branched, weakly conglutinated in water, especially at the apices, becoming ± free in K, a brown pigment surrounding the 1-2 uppermost cells; upper cell clavate, to ca 5 μm diam. Asci subcylindrical to clavate, with a thin external and internal K/I+ dark blue cap, surrounded by a thick K/I+ pale blue, gelatinous apical cap but a K/I– apical tube in the tholus, 8-spored. Ascospores 9.5-13 (-14) × 5-5.5 (-6) μm, reniform to fabiform, aseptate, fairly thin-walled, smooth, without an epispore, gelatinous sheath or appendages. Chemistry: thallus K+ brownish yellow, Pd+ rust-red, UV– (fumarprotocetraric acid).