Thallus effuse and wide-spreading, or forming small, poorly delimited patches amongst other species, thin, ± continuous, pale grey and rather scabrid or (especially on smooth bark) with scattered areoles on a dark, thin, blue-grey prothallus. Soralia usually numerous, efflorescent, discrete, 0.2-1 mm diam., or often confluent, pale yellowish-green to blueish grey; soredia 30-80 (-100) µm diam., external hyphae often blue-grey, N+ red. Photobiont chlorococcoid. Anamorph: unknown. Teleomorph: unknown. Chemistry: thallus, medulla and soralia C–, K–, KC–, Pd–, UV+ white (perlatolic acid).