Description: Thallus crustose, endosubstratic or very thinkly episubstratic, whitish, often poorly evident. Perithecia black, globose, 0.3−0.7 mm across, projecting from the substrate. Involucrellum black, tightly incurved around the exciple and often completely surrounding it; exciple globose, colourless or pale brownish; hamathecium of persistent, slender, 1.2−1.4 μm thick, sparingly branched, long-celled pseudoparaphyses; periphyses absent; hymenial gel I-, K/I-. Asci 8-spored, cylindrical, K/I-, fissitunicate, the apical dome with a broad ocular chamber surmounted by a hemispherical meniscus-like structure. Ascospores 1-septate, hyaline, broadly ellipsoid, 12-14(-18) x 5-7(-8.5) μm, uniseriately arranged in the asci, surrounded by a perispore which appears verrucose in water, smooth in K. Photobiont trentepohlioid. Spot tests: K-, C-, KC-, P-, UV-. Chemistry: without lichen substances.
Note: this calcicolous species (also occurring on calciferous sandstone) is characterised by sessile perithecia and a basally closed (entire) involucrellum; the type material is from the Sudety Mts., and the species is also known from the French Southern Alps and Turkey, mostly in the montane belt; it should be looked for in Italy.