Punctelia subrudecta (Nyl.) KrogThallus foliose, heteromerous, dorsiventral, forming 5-10 cm wide. usually regular rosettes, sorediate. Lobes tightly adpressed, 5-10 mm wide, rounded and ascending at apices, eciliate, grey or grey-green, with white, punctiform pseudocyphellae giving rise to white, orbicular, laminal soralia. Lower surface whitish to dark brown towards margins, pale brown towards center, with simple rhizines. Upper cortex paraplectenchymatous, of 2-6 layers of densely packed cells, with a non-pored epicortex, the cell walls with isolichenan; medulla white; algal layer continuous; lower cortex paraplectenchymatous. Apothecia very rare, lecanorine, 3-5 mm across, with a brown disc and a raised, often sorediate thalline margin. Proper exciple thin, colourless; epithecium brownish; hymenium and hypothecium colourless. Asci 8-spored, clavate, <i>Lecanora</i>-type. Ascospores 1-celled, hyaline, broadly ellipsoid, 14-18 x (7-)10-13(-15) µm. Pycnidia black, laminal. Conidia hook-shaped, 4-5 x c. 1 µm. Photobiont chlorococcoid. Spot tests: upper cortex K+ yellow, C-, KC-, P- or P+ very faintly yellow; medulla and soralia K-, C+ red, KC+ red, P-, UV-. Chemistry: upper cortex with atranorin, medulla and soralia with lecanoric acid.
