Thomson, J. W. (1997). American Arctic Lichens: The microlichens (Vol. 2). Univ of Wisconsin Press.

Thallus lacking or a thin, continuous, finely chinky, soft chalky white crust; hypothallus lacking. 

Apothecia adnate with narrow base, to 3.5 mm broad, shining, black, epruinose, lacking umbo, flat at first, the center becoming raised and the disk gradually fissuring and breaking away, new apothecia arising from the remaining attached portions; exciple darker inward and paling to the outside as in Porpidia macrocarpa, brownish, the color extending deeply into the hymenium; hypothecium red-brown, K+ violet, darker than exciple; hymenium 70-90 µm, upper part blue-green, lower red-brown, in thin sections almost hyaline; paraphyses strongly swollen, gelatinous, branched and anastomosing, 2-2.5 µm, tips to 5 µm; asci clavate; spores poorly developed, ellipsoid with tips slightly pointed, often halonate when young, 11-21 X 5-9 µm.  (Description after Hertel 1967.)

Reactions: K-, C-, KC-, P-; medulla weakly I+ blue; exciple and hypothecium K+ red-violet.

This species grows on calcareous rocks, sandstones or limestones.  It is circumpolar arctic-alpine, in North America ranging south to Utah and Illinois.

Thallus lacking or a thin, continuous, finely chinky, soft chalky white crust; hypothal-lus lacking. Apothecia adnate with narrow base, to 3.5mm broad, shining, black, epruinose, lacking umbo, flat at first, the center becoming raised and the disk gradually Assuring and breaking away, new apothecia arising from the remaining attached portions; exciple darker inward and paling to the outside as in Porpidia macrocarpa, brownish, the color extending deeply into the hymenium; hypothecium red-brown, K+ violet, darker than exciple; hymenium 70-90 μm, upper part blue-green, lower red-brown, in thin sections almost hyaline; paraphyses strongly swollen, gelatinous, branched and anastomosing, 2-2.5 μm, tips to 5 μm; asci clavate; spores poorly developed, ellipsoid with tips slightly pointed, often halonate when young, 11-21 x 5-9 μm. (Description after Hertel 1967.)

Reactions: K—, C —, KC —, P —; medulla weakly 1+ blue; exciple and hypothecium K+ red-violet.

This species grows on calcareous rocks, sandstones or limestones. It is circumpolar arctic-alpine, in North America ranging south to Utah and Illinois.