Description: Thallus crustose, of scattered to crowded, bright yellow, smooth, mostly round and convex, 0.04-0.2 mm wide, corticate granules. Apothecia rather frequent, yellow, lecanorine, 0.2-0.9 mm across, with an initially entire, later granular, raised to finally excluded margin and a darker yellow, flat to finally convex disc. Epithecium yellow-brown; hymenium colourless, 55-70 µm tall; paraphyses simple, cylindrical or somewhat swollen at apex, the tips to 3 µm wide; hypothecium colourless. Asci 16-24-spored, clavate, with an apical dome which is I+ blue only in the internal, lower part, interrupted in the centre by a a paler blue strip, Candelaria-type. Ascospores simple to 1-septate, hyaline, ovoid to oblong, 7.5-12 x 3.5-5 µm. Pycnidia common, appearing as darker yellow granules. Conidia hyaline, ellipsoid to oblong, 2.5-3.5 x 1.5 µm. Photobiont chlorococcoid. Spot tests: thallus K- or K+ faintly orange, C-, KC-, P-. Chemistry: calycin, pulvinic acid, pulvinic dilactone and vulpinic acid.
Note: a mild-temperate to cool-temperate, perhaps holarctic species found on bark of more or less isolated trees, especially oaks, but also on conifers, much more rarely on lignum, with optimum in the deciduous forest belts.