Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus areolate, thick or thin, the areolae to 0.8 mm broad, rounded or angular, convex or flat, commonly slightly shining, ashy gray; black hypothallus present. Apothecia to 1.0(—1.8) mm flat to convex, black, dull or shining; margin thick or thin, usually persistent; exciple red-brown; disk slightly roughened; hypothecium red-brown to black; epithecium green-black; hymenium 140 µm, pale to brownish, greenish above; paraphyses capitate, coherent, tips dark; spores 8, 1-septate, soon dark bluish black, with halo, 20-30 X 9-12 µm.
Reactions: medulla K+ yellow turning red, C —, P+ yellowish, I—; exciple K+ red with red needle-like crystals produced; hypothecium K+ red; epithecium K—.
Contents: norstictic acid. Runemark (1956) also listed stictic acid but this was not confirmed in GAo-T tests.
This species grows on acid rocks. It is circumpolar arctic to boreal, in North America ranging south to Washington.