Description: Thallus crustose to subleprose, whitish to whitish grey, up to 0.7 mm thick, entirely consisting in a mass of granules, usually well-delimited, sometimes indistinctly sublobate at margin, forming up to 10 cm wide patches (usually less). The thallus starts developing as isolated, dispersed granules that form piles, or aggregations (best visible along the margins, where the dispersion of the young granules is most readily observed) which eventually overlap and become confluent, giving the false appearance of a continuous thallus in older areas. Granules rather firmly attached, coarse, 80-150 μm in diam., sometimes gathered into 200-300 μm wide aggregates, with a well-developed pseudocortex, th surface appearing compact, rarely with very short projecting hyphae; Medulla white and cottony, rather thin (0.3-0.5 mm), often partially exposed. Photobiont chlorococcoid. Spot tests: K- or K+ pale yellow, C-, KC- or KC+ yellow, P- or P+ pale yellow, UV-. Chemistry: atranorin, porphyrilic acid and a fatty acid (roccellic/angardianic or rarely rangiformic acid); very rarely fatty acids and/or atranorin can be absent.
Note: on epilithic mosses and soil in alpine grasslands, in rain-subjected sites with a long snow-lie, both on siliceous and weakly calciferous substrata, up to the nival belt in the Alps; rather common in the Alps, where it reaches the nival belt, rarer elsewhere in Italy.
Growth form: Leprose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)