Ochrolechia parella  

Description taken from Smith et al. (2009). Thallus thick, smooth to granular-warted, often fissured, grey-white, ± orbicular, often concentrically ridged and markedly zoned at circumference, surrounded by a white prothallus. Ascomata usually numerous, crowded, round or irregular-compressed, 2-5 mm diam; disc deeply concave when young, becoming flat, pale pink-brown, often thickly and coarsely grey-white pruinose; thalline exciple thick and swollen, at times almost closing over disc, smooth, entire; epithecium granular, the granules dissolving in K. Ascospores 45-65(-88) x 25-40 (-50) µm, broadly ellipsoidal.

Thallus C+ yellow, K-, KC+ yellow, Pd-, UV- or slightly blue (variolaric acid); ascomatal disc pruina and proper exciple C+ red, K-, KC+ red, Pd-, UV- (gyrophoric acid).