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Polyblastia hyperborea Th. Fr.
Family: Verrucariaceae
Polyblastia hyperborea image
Lucy Taylor  
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus varying from nearly lacking to a chinky-areolate crust, when present ashy gray to whitish. Perithecia with base immersed in rock, 0.2-0.3 mm broad; exciple pale below, black above and merging with black involucrellum which extends about halfway down perithecium into thallus tissue and spreads widely; gelatin 1 + red; spores hyaline, muriform with many cells, up to 6-8-septate transversely and 2- or 3-septate longitudinally, 25-45 x 13-23 µm. Those with spores 30-45 X 17-28 µm are placed by Lynge (1926) in var. macrospora Lynge. Those with spores 25-30 X 13-17 µm were considered typical for the species.

This species grows on calcareous rocks, sometimes partly immersed in the rock. It is circumpolar arctic.