Description: Thallus crustose, episubstratic, finely granular (granules 0.4-0.6 mm) or of verrucose granules (0.12-0.15 mm), ecorticate. Apothecia stalked, pin-like, the stalk 1.1-1.5 mm high, 0.04-0.11 mm thick, black but often covered in a thin, greyish pruina formed by a layer of ruptured surface hyphae. Capitula spherical, 0.3-0.4 mm across, with a poorly developed, up to 30 µm thick exciple which only surrounds the bare of the capitulum as a collar, sometimes missing. Mazaedium well-developed, brown, without crystalline pruina, but the lower side of the capitulum sometimes appears white-pruinose due to pale hyphae projecting from the exciple; hypothecium broadly obconical, with a strongly convex to hemispherical upper surface. Asci cylindrical, ellipsoid or irregular, formed in chains, dissolving early, with 1- or 2-seriate ascospores. Ascospores 1-celled, brown to pale brown, globose, 3-4.5 µm wide, the wall smooth or with irregular fissures. Photobiont trebouxioid, the cells < 10 µm diam. Spot tests: thallus K-, C-, KC-, P- or P+ yellowish(-orange), UV+ white. Chemistry: thallus with barbatic and obtusatic acids, rarely with squamatic acid.
Note: described from South America, this species is widespread in temperate and cool-temperate areas of the Southem Hemisphere, rare in the Northern Hemisphere, in Europe being known from a few localities scattered from Scandinavia to the montane belt of the Central Alps (Switzerland), in very shaded localitites at bases of old trunks. To be looked for in Italy.