Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus white, thin to moderately thick, smooth to warty, dull, often pruinose, continuous, not fissured-areolate, lacking soredia or isidia. Fertile verrucae with base constricted, crowded; ostioles black, level to sunken. Apothecia 1 per verruca to 0.7 mm broad; hypothecium hyaline; epithecium dark brown or black, K+ violet; hymenium hyaline; asci cylindrical; spores 4 (rarely 2, 3, or 5), uniseriate oblique or biseriate irregular, walls double, outer wall 1-3 μm, inner 1-5 μm, smooth, usually with 24 x 6—11 μm.
Reactions: K— or K+ red; C—, P—, I— (usually).
Contents: Gowan (1989) lists four chemotypes: 1. with confluentic acid, and accessory 2'-0-methylperlatolic acid and other substances, 2. with norstictic and connorstictic acids, 3. with combination of 1 and 2, and 4. lacking substances.
This species grows on rocks in partial shade in the tundras, often in rock trains over hidden trickling water. It ranges from the high to low Arctic and is circumpolar, in North America ranging south in the East to Mt. Washington, New Hampshire, in the West to British Columbia.