Description: Thallus crustose, yellow to (more rarely) orange yellow, starting the life-cycle on different epilithic lichens, from granulose to irregularly areolate, often slightly lobulate at margins, forming well-delimited, to 1 cm wide, round patches, but most frequently forming very irregular patches, several thalli often coalescing. Cortex paraplectenchymatous, orange brown in outer part, colourless in inner part, the pigmented parts K+ red, of thin-walled cells; medulla poorly developed, I-. Apothecia frequent, immersed when young but soon sessile, 0.3-1 mm across, with a flat to slightly convex, yellow to yellow-orange disc and a somewhat paler, persistent margin. Epithecium with orange-brown crystals soluble in K, K+ red; hymenium and hypothecium colourless; paraphyses mostly unbranched, c. 1.5 μm thick in lower part, the apical cells up to 4 μm wide. Asci 8-spored, cylindrical-clavate, functionally unitunicate, apically thickened with a broad internal beak, the inner part of apex and external cap I+ blue, Teloschistes-type. Ascospores 2-celled, polarilocular, hyaline, ellipsoid, 10-13(-14) x 6-8 μm, the equatorial thickening (“septum”) 3-5(-8) μm. Photobiont: chlorococcoid. Spot tests: thallus and apothecia K+ red, C-, KC-, P-. Chemistry: thallus and apothecia with parietin (major), fallacinal, emodin, teloschistin and parietinic acid (minor), corresponding with chemosyndrome A of Søchting (1997).
Note: a mild-temperate species found on the top of isolated calcareous boulders and rock outcrops, on calcareous rocks wetted by rain in sunny situations, especially common on Acarospora cervina and Circinaria calcarea. The species, as currently understood, probably belongs to Athallia, but the poorly developed type material probably belongs in Variospora (Vondrák & al. 2016), so that the nomenclature of this lichen is likely to change in the near future. The relationships with C. necator still remain to be clarified.