Thallus to 5 cm diam., closely appressed, forming poorly defined rosettes or irregularly spreading. Lobes 1-3 mm wide, hollow, ± convex but flattened towards the ends, contiguous and overlapping, sometimes intricately convoluted in the centre, often ± discrete towards margins; upper surface grey-green, wrinkled except at the thallus edge which is brownish and with a network of pale pseudocyphella-like lines on the upper surface. Soralia spreading, laminal, forming on the ridges of the wrinkles. Lower surface black. Anamorph: not observed. Teleomorph: ascomata apothecia, not observed in British material. Chemistry: cortex K+ yellow; medulla C–, K–, KC+ red, Pd–, UV+ pale violet-blue (chloroatranorin, atranorin, physodic and 3-hydroxyphysodic acids, and some unknowns).