Description: Thallus crustose, episubstratic, rather thick (0.2-0.4 mm), whitish to pale grey-brown, areolate, often delimited by a black prothallus. Areoles flat to convex, more or less angular, 0.3-0.8(-1.5) mm wide, developing on a black hypothallus. Cortex densely inspersed with small crystals dissolving in K; medulla white, I- or I+ faintly violet. Apothecia lirelliform, black, slightly raised over the thallus, 0.2-1.5 x 0.2-0.4 mm, simple or sparingly branched, sometimes stellate, straight or curved, somewhat shiny, with a raised, inward-turned margin hiding the slit-like disc. Exciple black, carbonized; epithecium dark brown, granulose; hymenium colourless to brownish, 60-95 µm high, not inspersed with oil droplets, I+ blue; paraphyses slender, up to 1 µm thick, mostly simple, not capitate. Asci 8-spored, cylindrical to subclavate, the tholus with K/I+ dark blue flanks and a broad non-amyloid axial mass, Trapelia-type. Ascospores 1-celled, hyaline, ellipsoid to ovoid, 9-15 x 5-8 µm. Photobiont chlorococcoid. Spot tests: medulla K+ yellow turning red, C-, KC+ red, P+ faintly yellow-orange, UV-. Chemistry: norstictic acid in the medulla.
Note: on sheltered base-rich siliceous rocks in humid upland areas; probably restricted to the Alps in Italy.
Growth form: Crustose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly sexual
Most common in areas with a humid-warm climate (e.g. most of Tyrrenian Italy)