Distribution: N - Emil (Nimis & al. 1996, Fariselli & al. 2020), Lig. C - Abr (TSB 25008), Sar.
Description: Thallus crustose, episubstratic, verrucose-areolate, sulphur- to orange-yellow, more or less pruinose, 1-2(-3) cm broad. Areoles flat to mostly convex, contiguous, often sitting on a rather thick hypothallus, the marginal ones sometimes elongate, to 1-2 mm long, the central ones strongly convex, almost verrucose, 0.3-0.5 mm tall. Upper cortex paraplectenchymatous, with an epinecral layer; medulla white, 40-160 μm thick; lower cortex absent. Apothecia lecanorine, sessile, 0.5-1.5 mm across, with an orange to brownish orange, flat to slightly convex, rugose disc, and a thin margin which at maturity separates into a darker and thinner proper margin and a paler thalline margin. Epithecium orange-brown, K+ red; hymenium colourless, >70 µm high; hypothecium colourless. Asci 8-spored, clavate, -type. Ascospores 1-septate, often slightly constricted at septum, not polarilocular, hyaline, ovoid-ellipsoid, thin-walled, 10-17 x 4-8 μm. Pycnidia orange-yellow, immersed. Conidia oblong, 3-3.5 x 1-1.2 μm. Photobiont chlorococcoid. Spot tests: thallus and apothecia K+ red, C-, KC-, P-, UV+ pale orange. Chemistry: thallus and apothecia with fragilin (major), emodin, parietin and other anthraquinones (minor).
Note: in Italy only locally common, especially in areas with gypsum, in open grasslands; to be looked for also in dry-continental Alpine valleys.
Growth form: Crustose
Substrata: soil, terricolous mosses, and plant debris
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)