Verrucaria sphaerospora  

Thallus superficial, areolate to subsquamulose, 0.5-1 mm thick, upper surface grey to brownish grey, wrinkled to finely cracked, dull, pruinose or not. Areoles subangular, to crenate at margin, 0.5-2 mm diam., subdivided into smaller units by fine pale brown cracks, but never by black lines, the upper surface of areoles sometimes granular-verrucose (composed of goniocysts). Sides of areoles in lower part ± dark brown, but in upper part concolourous with the upper surface. Upper cortex composed of 1-2 layers of round to angular brown cells. Algal layer 100-150 µm thick, algal cells 8-13 µm in diam. Medulla in upper part hyaline, paraplectenchymatous, in lower part brown and prosoplectenchymatous with thick hyphae.

Anamorph: not observed.

Teleomorph: ascomata perithecial. Perithecia one to several per areole, often between the smaller units, completely to rarely half-immersed. Involucrellum black, 35-50 µm thick, completely encircling the exciple. Exciple globose, brown to dark brown, 200-300 µm wide. Periphysoids 20-30 µm long, simple or sparsely branched. Asci oblong-clavate, 60-75 µm long, 13-20 µm wide. Ascospores simple, colourless, globose to subglobose, 9-12 × 7.5-10 µm.