Distribution: N - Emil (Nimis & al. 1996, Fariselli & al. 2020).
Description: Thallus crustose-placodioid to subsquamulose, greenish-yellow, but usually densely covered with a thick layer of white, granular pruina, areolate, with radiating marginal lobes, forming up to 5 cm wide patches, often starting the life-cycle on terricolous species of Diploschistes, later autonomous. Areoles convex, contiguous; marginal lobes c. 2 mm broad. Medulla thick, white. Apothecia lecanorine, rounded, semi-immersed in the areoles and not constricted at base, 1-5 mm across, with a slightly concave to flat, dark reddish brown to almost black, somehow shiny, smooth disc, and a thick thalline margin. Epithecium brown; hymenium colourless, 100-150(-200) µm high, I+ blue; paraphyses numerous, coherent, simple to sparsely branched in upper part, 1-1.5 µm thick at base; hypothecium colourless. Asci 50-100-spored, clavate, with a distinct apical dome, K/I-. Ascospores 1-celled, hyaline, subglobose, 4-6 x 4-5 µm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: rhizocarpic acid and an unknown terpenoid.
Note: a xeric subtropical species found on weathered gypsum in open situations, mostly below the montane belt. To be looked for in gypsum outcrops of southern Italy (e.g. in Sicilia).
Growth form: Crustose placodiomorph
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Subcontinental: restricted to areas with a dry-subcontinental climate (e.g. dry Alpine valleys, parts of Mediterranean Italy)