Description: Thallus inapparent, not lichenized, the hyphae developing inside the thalli of Pertusaria-species, forming orbicular necrotic patches. Apothecia arthonioid, black, epruinose, rounded to angular, convex, 0.4-3.5 mm across, without a distinct margin, surrounded by radiating black hyphae. Proper exciple absent or much reduced, appearing as a thin dark rim in the marginal and basal parts of the hypothecium; epithecium brown-red, K+ olive-green; hymenium colourless, 60-70 µm high; paraphysoids coherent, branched and anastomosing, the apical cells up to 4-6 µm wide, with a dark cap; hypothecium colourless to pale brown 10-20 µm high, K- or K+ olive-green. Asci 8-spored, subglobose, semi-fissitunicate, with a large apical dome and an ocular chamber, Arthonia-type. Ascospores (2-)3(-4)-septate, at first hyaline and smooth, later covered in dark brown granular warts, with one of the apical cells distinctly larger than the others, 14-20 x 6-7 µm, thin-walled. Photobiont absent. Spot tests: K-, C-, KC-, P-. Chemistry: without lichen substances.
Note: a lichenicolous fungus described from Spain, growing on the thalli of Pertusaria pustulata; to be looked for in Tyrrhenian Italy.