Thallus orbicular, rosette-forming to irregularly spreading, ± closely attached centrally, margins free, 5-8(-10) cm diam. Lobes short, 3-6 mm wide, rounded, ± cochleate, imbricate, concave to plane or subconvex, irregularly undulate, margins entire to minutely crenulate, distinctly thickened, with conspicuous, punctiform, yellow pseudocyphellae. Upper surface dark leaden-grey, blackish or dark olive-reddish in parts when wet, pale grey-brown or buff when dry, margins brown or red-brown, maculate (×10 lens), maculae best seen when wet towards apices, margins yellow, sometimes suffused reddish-brown, free of algae, undulate or minutely wrinkled, not reticulate-faveolate, distinctly tomentose especially towards centre of lobes, not sorediate, isidiate or pseudocyphellate. Tomentum pale fawnish or whitish, downy, short, mainly laminal, rarely marginal. Medulla white, in places very pale yellow. Photobiont blue-green. Lower surface wrinkled uneven, pale buff or whitish at margins, darkening slightly towards centre, tomentose. Tomentum rather thin, whitish or pale buff, to margins. Pseudocyphellae yellow, conical-verruciform, projecting above tomentum, minute, 0.05-0.1 mm diam., sparse to moderately frequent. Apothecia not seen. Chemistry: Hopane-6α,7β,22-triol, hopane-7β,22-diol, 6α-acetoxyhopane-7β,22-diol, 7β,-acetoxyhopane-6α,22-diol, pulvinic acid, pulvinic lactone, calycin, tenuiorin, methylgyrophorate, stictic, constictic and norstictic acids. The species has a distinctly fishy smell when moistened, (?methylamine).