Description: Thallus crustose-placodioid, closely attached, yellow, well-delimited, forming regular rosettes to 4 cm diam, individual thalli often merging to cover larger surfaces. Thallus center granulose-areolate, often tending to become grey, sometimes dying off, covered by granular isidioid outgrowths which soon produce soredia-like granules; lobes 0-3-1 mm wide, radiating, contiguous, flat to slightly convex, sometimes pruinose especially at the tips. Apothecia extremely rare, yellow, 0.5-2 mm across, with a flat, often yellow-pruinose disc and an entire to granulose thalline margin. Asci 8-spored, clavate, Candelaria-type. Ascospores 0(-1)-septate, hyaline, elliptical to tear-shaped, 11-18 x 4-7 µm. Photobiont chlorococcoid. Spot tests: thallus K- or K+ faintly orange, C-, KC-, P-. Chemistry: thallus and apothecia with pulvinic acid derivatives.
Note: a mild-temperate lichen found on man-made calcareous substrata (churches, other monuments, top of statues in parks and of gravestones), especially above the Mediterranean belt, but also on the top of isolated calcareous boulders in natural situations, abundant in small villages along the eastern portion of the Apennines.
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)