Thallus white or ashy white, thin, effuse, very soft, not orbicular or lobate, irregularly chinky-areolate, quite continuous, merging into a thin, indistinct, ashy hypothallus, the sterile parts low and ashy-yellowish, the fertile parts elevated and convex but not verrucose.
Apothecia in raised vemicae, single or several per verruca;
disk to 0.5 mm broad, concave, black, lightly pruinose; margin raised, pale-banded, sides of apothecium dark ashy;
hypothecium pale;
epihymenium brownish, HCI+ green;
hymenium 80-100 µm, upper part yellowish brown. 1+ blue turning red; paraphyses slender, easily separable in KOH, not moniliform, becoming branched and interwoven;
spores 8, hyaline, ellipsoid, 16-20 x 7-10 µm.
Conidia unknown.
Reactions: K-, C-, 1-.
This species grows on calcareous and noncalcareous rocks. It ranges from Greenland across North America to Alaska.
