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Placidiopsis cervinula (Nyl.) Vainio
Family: Verrucariaceae
Placidiopsis cervinula image
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus of small squamules to 3.5 mm broad, flat to slightly wavy, brown to ashy brown or ashy, margin black, underside black, over black hypothallus. Perithecia scattered over thallus, tips black and projecting slightly above thallus level, with a white dot at the ostiole; entire and dark brown in section, to 140 µm broad; asci thick-clavate; spores 8, biseriate, hyaline, tips rounded, 2-celled, 14-23 x 8-11 µm.

This is a very rare lichen known from Lapland (Zschacke 1933-1934), Mongolia (Golubkova 1981), and recently collected in Alaska, Arrigetch Valley, Brooks Range, Cooper 353 (WIS), and at Frobisher Bay, Northwest Territories.