Thallus of minute granules, subleprose or entirely granulose-sorediate, snow-white. Apothecia sessile, to 1 mm broad; margin thick, white, becoming farinose; disk concave, pale to darker flesh-colored, smooth; hypothecium hyaline; epithecium yellowish green; hymenium 195-205 μm; spores 8, ellipsoid, 32-44 X 21-23 μm.

Reactions: thallus K—, C+ red, KC + red, P-; disk K—, C+ red, KC+ red, P—; soredia P+ orange.

Contents: gyrophoric acid, atranorin, and two unknowns (Ahti et al. 1973).

This species grows on calcareous soil, wood, Picea bark, and rocks. It is known from Siberia, possibly Spitzbergen, and North American tundras.

This species is very closely related to O. inaequatula but has a much more abundant thallus with finer soredia.