Arthonia epimela  

Anamorph: not known.
Teleomorph: ascomata apothecia, 0.4-0.6 mm diam., black, round in outline, convex, sessile. Hypothecium thick, sometimes with a narrow dark base. Hymenium colourless, reddish in iodine, with a dark epithecium composed of free paraphysis tips. Asci 30-35 x 13-16 µm, narrowly pyriform, 8-spored. Ascospores 9-13 x 3-4 µm, cylindric-clavate, 1-septate, colourless.