Micarea denigrata (Fr.) Hedl.

    Thallus very variable, thin, areolate, granular, gray-greenish but most often not very visible or seeming absent, greyish, blackish, brownish, etc. Apothecia very numerous, 0.2-0.5 mm in diameter, brownish, blackish, disc slightly convex at the beginning then quickly strongly convex and giving a globular appearance at the apothecia, irregular and bumpy surface, very fine margin disappearing quickly. 8-spore asci. Colorless spores, elliptical, straight and sometimes a little curved which gives them a somewhat bacilliform appearance, 1 time septate giving 2 unequal cells, 7-9 x 2.5-3 µm. Photobiont: green algae. C +/- red-orange, K-, KC-, P-. Relatively common species coming on damp worked wood, in particular in dirty and ruderal places: fences, posts, bordered by wrecks of wooden boats, ... even coming from painted wood whose paint is degraded; Micarea denigrata sur bois peint and sometimes even on painted metal from wrecks in boat cemeteries: Micarea denigrata sur métal peint.

N.B. The sterile form, or partially sterile, is quite common, it is characterized by the presence of black pycnidia, more or less immersed in the thallus, with an ostiole letting a whitish gummy jelly containing mesoconidia flow. The thallus then appears as studded with small white dots.