Phaeophyscia nigricans (Flörke) Moberg

    Thallus more or less loosely attached, rosette-forming, 1-1.5 cm diam., lobes indented, narrow, oriented radially, 0.1-0.3 mm wide, overall colour greenish, grey-olive, olive when moist, greyish to grey-brownish when dry, upper surface smooth, scattered with many marginal isidioid soredia, dark brown-olive towards lobe margins, in addition presence of minute hyaline monocellular cilia at lobe apices, lower surface with scarce simple rhizines, paler than upper surface, dull whitish, pale brownish. Sterile. C-, K-, KC-, P-, UV-. Rare, or understated, on humid and dull calcareous rocks (tombstones), sometimes at the basis of ornmental trees, also on dull fibre cement roof of buildings. See Phaeophyscia hirsuta, much larger and with pluricellular marginal cilia. Not to be confused with small forms of Phaeophyscia orbicularis of which lower surface is blackish.