Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus continuous to verrucose or areo-late, pale yellow, cream-yellow, or greenish yellow, with round to elliptical well-limited soralia surrounded by a compact pseudocortex often containing crystals, the soredia gray-green or blue-green; the medullary hyphae very thick, 5-6 μm, with walls 1-2 μm. Apothecia rare, 0.2-0.9 mm; margin sometimes biatorine but usually thick, persistent and sorediate; margin with 15-20 μm cortex which breaks down into soredia; medulla with granular crystals which dissolve in KOH; disk becoming convex, reddish to yellowish brown; hypothecium hyaline; epihymenium brown, granular at surface; hymenium 55-65 μm, hyaline; spores ellipsoid to narrowly ellipsoid, 9.5-14.5 x 4-5.2 μm. Conidia rare, filiform, curved, 15-19.5 x 0.5 μm.
Reactions: K—, C+ orange, KC+ orange.
Contents: usnic acid, zeorin, thiophanic acid and two accessory xanthones (Brodo & Vanska 1984).
This species grows on driftwood, logs, fence rails, and old wood along shores and beaches. It is circumpolar boreal and arctic, but not yet found in Greenland.