Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus crustose, white to sooty yellow, 0.5-1.8 mm thick, smooth to chinky, verru-culose; no distinct hypothallus present. Apothecia to 1.5 mm broad, adnate, shining, black, flat to high-convex; exciple exterior green-black to blue-black, interior pale; hypothecium hyaline to pale yellowish; epihymenium green to blue-green; hymenium 70-90 μm, inspersed with oil drops, hyaline; paraphyses ca. 2 μm, occasionally branched, tips to 5 μm; asci clavate; spores ellipsoid to broadly ellipsoid 10.5-17 x 6-10.5 μm.
Reactions: K—, C—, KC—, P—, I—; hymenium 1+ blue, the asci turning violet. (Hertel (1973) records that occasionally the medulla is K+ yellow with atranorin.)
Contents: occasionally with atranorin (Hertel 1973); ± zeorin (Knoph 1990).
This species is found on calcareous rocks in very dry habitats. It is circumpolar, arctic-alpine to xeric-temperate, in North America being known from Colorado, Wyoming, Utah, South Dakota, and Saskatchewan.
In several publications Hertel (1968, 1970a, 1973) has pointed out that this species, with its thicker thallus, is part of a series, with L. inamoena at the opposite end, lacking thallus, and L. spitsbergensis, with scant thallus, as the intermediate. The three may all be expressions of one species with environmental modification of the amount of thallus.