Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus squamulose, the squamules to 1.5mm broad, crenulate and laciniate, becoming confluent, flattened, greenish gray, pale yellowish, or whitish; hypothallus indistinct. Apothecia adnate, the base slightly constricted, partly conglomerate; disk flat to very convex, becoming immarginate, black; exciple red-brown inside, exterior paler, radiate; hypothecium reddish brown; epihymenium brown to blackish brown, inspersed (pruinose) above; hymenium 70-80 μm, upper part brownish to brown or olive or bluish; paraphyses coherent, not branched, upper part colored and thickened; spores 8, hyaline, 1-3-septate, fusiform or oblong-elongate, 12-25 x 3-6 μm.
Reactions: thallus K—, C —, P—, I—; hypothecium K+ purple; epihymenium K+ purple, HN03 —; hymenium 1+ blue turning red.
Contents: zeorin. In three specimens: Murray 4187 from Beaufort Lagoon, Alaska, Johnson 2041 from the Kazan River, Keewatin District, Northwest Territories, and Thomson 13,439 from Cambridge Bay, Victoria Island, Northwest Territories, this was accompanied in GAo-T tests by crystals appearing to be nephrin. The nephrin was slow in appearing, as already pointed out by Wetmore (1960) for Nephroma arcticum.
This species grows on calcareous soils and among moss as well as on humus. It is circumpolar arctic-alpine, ranging south in North America to Quebec, Wyoming, Colorado, and Washington.