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Psora vallesiaca (Schaerer) Timdal
Family: Psoraceae
Psora vallesiaca image
Timdal, Einar  
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus squamulose, the squamules to 5 mm broad, usually 2-4 mm, adnate with only the margins ascending, medium thick, brown to reddish brown, epruinose or partly white pruinose, margins white, underside pale brown; lower cortex poorly developed. Apothecia to 1.2 mm broad, black, dull, sometimes partly white pruinose; exciple exterior reddish, interior hyaline; paraphyses tips slightly elongated; spores ellipsoid, 9-13 x 5-7 μm. Conidia 5-7 x 1 μm.

Reactions: K+ red, C—, KC—, P+ yellow, I —.

Contents: norstictic acid in medulla, parietin in hymenium.

This species grows on calcareous soil. It is known in North Africa, Europe, Greenland, and at Polar Bear Pass on Bathurst Island, Northwest Territories.