Prothallus whitish, non-fimbriate. Thallus epilithic, 35–100 µm thick, dark grey-brown to brown-black, sometimes with a greenish tinge; cracks sparse to numerous, but rarely delimiting discrete areoles except in very local thicker areas; surface roughened with indistinct, concolorous punctae or short flexuose or branched ridges; thallus gradually thinning to margin. Pseudocortex with dilute to moderately dense brown pigment, K– or almost so. Epinecral layer sometimes present, ca 4 µm thick, colourless, of collapsed cells, the structure difficult to discern. Basal parts of thallus colourless to brown, living photobiont cells few or absent, densely pigmented areas (punctae) projecting from basal layer into photobiont layer, pigment dark red-brown, K+ dark grey-brown. Ascomata perithecia, forming conspicuous conic-hemispherical projections 260–500 µm diam, roughened below like the thallus, above smooth, concolorous with thallus or black, apex rounded or slightly flattened, ostiolar region concolorous, inconspicuous. Involucrellum well-developed, merging with dark basal tissue. Asci 45–82 × 18–29 µm, 8-spored. Ascospores (12.5–) 13.5 –16.5 (–18) × (5.5–) 7–8 (–8.5) µm, length/width ratio (1.4–) 1.8–2.3 (–2.7), cylindric-ellipsoidal.