Description: Thallus crustose, episubstratic, bright yellow, consisting of scattered to usually contiguous, 0.05-0.1 mm wide, flat to slightly convex, subsquamulose areoles which burst into granular blastidia, forming orbicular patches to 1(-2) cm in diam., which often coalesce to cover much larger surfaces. Apothecia frequent, lecanorine to finally biatorine, scattered to contiguous, constricted at base, with an initially flat, brownish yellow disc, and a thick and prominent, often granulose-blastidiate, bright yellow thalline margin, later often with a convex disc and immarginate. Thalline esciple corticate, paraplectenchymatous, filled with algae; proper exciple wider in upper part, more evident in old apothecia; epithecium yellow, granulose; hymenium colourless, 70-95 μm high; paraphyses 1.5-2 μm thick, the apical cells not or only slightly swollen; hypothecium colourless. Asci 8-12-24-32 spored in the same apothecium, clavate, with an apical dome which is I+ blue only in the internal, lower part, interrupted in the centre by a I+ paler blue strip, Candelaria-type. Ascospores 1-celled, hyaline, straight or slightly curved, with rounded ends, often biguttulate, 12.5-15 x 3.5-5 μm, more or less of the same size in all asci, irrespectively of their number. Photobiont chlorococcoid. Spot tests: thallus K- or K+ faintly orange, C-, KC-, P-. Chemistry: calycin, pulvinic acid, pulvinic acid-dilactone.
Note: A species with a thallus composed of minute roundish squamules, later forming granulose blastidia, and asci with a variable number (8 to 32) of ascospores, found on bark of deciduous trees (e.g. of Fagus in more or less closed forests; widespread but not common in forests of the montane belt in Mediterranean orobiomes; most frequent in beech forests of central and southern Italy.