Thallus ± orbicular to spreading, 2-6(-9) cm diam., often in small, closely attached rosettes. Lobes rounded to elongate-laciniate, imbricate, to 2 cm wide, margins crenulate-incised, sorediate, often sinuous. Upper surface dark bluish-purple when wet, pale blue-greyish-fawn when dry, conspicuously maculate (×10 lens), smooth, slightly scabrid at lobe apices, undulate, wrinkled-corrugate centrally, matt or shining, sorediate, without isidia or pseudocyphellae. Soredia golden yellow often somewhat reddish, coarse, granular, crowded, mainly marginal in ± continuous, erose to convolute-congested soralia, occasionally laminal on weakly defined ridges. Medulla yellow. Photobiont blue-green. Lower surface pale yellow, tomentose to margins, tomentum short, even, pale yellowish-white, brownish centrally. Pseudocyphellae golden-yellow, scattered, sparse, without a defined margin, 0.1-0.4 mm diam. Apothecia not seen. Chemistry: Pulvinic lactone, pulvinic acid, calycin, 2α-acetoxystictane-3β,22α-diol, 2α,3β,22α-triacetoxystictane, 2α,3β-diacetoxystictan-22α-ol,stictane-3β,22α-diol (±), 3β-acetoxystictane-2α,22α-diol (±), stictane-2α,3β,22α-triol (±). (Dr A.L. Wilkins in litt.).