Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus chalky white with a bluish tinge, in small rosettes to 2 cm broad, outer areolae lobate and radiate, about 1.5 mm long and 0.5 mm broad, convex, separated by cracks, central areolae angular, cortex and medulla filled with crystals; black hypothallus more or less visible. Apothecia in prominent vemicules, solitary or 2 or 3 per areola, surrounded by a thick margin which is black around disk, outer part of same color as thallus, margin K+ yellow, 14-blue; hypothecium hyaline, 1+ pale blue; epihymenium olive-brown; hymenium 75-120 µm, 1+ greenish yellow; paraphyses coherent, only partly moniliform, asci clavate; spores 8, ellipsoid, 9-16 x 7-10 µm.
Reactions: medulla K-, C-, P-, I-.
This species grows on calcareous rocks. It is circumpolar arctic, in North America ranging south to Utah and Colorado.