Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus at first perhaps facultatively parasitic, becoming auto trophic, bright yellow to yellow-orange, finely areolate, areolae rounded-angular, flat to somewhat convex, 0.2-0.5 mm broad. Apothecia on the areolae, usually 1 per areola, broadly adnate, 0.2-0.6 mm broad; margin paler yellow-orange, persistent, at the most slightly zeorine; exciple slightly radiate; disk flat to slightly convex, roughish, orange; hymenium 60-80 µm, the upper part granular; paraphyses capitate, tips to 6.5 µm and covered by episamma granules; spores 8, narrowly ellipsoid to spindle-shaped, small, 8—10.5(—13) x 3.5-4.5 µm, septum often poorly developed, 1-2.5 µm.
This species grows on calcareous silicate rocks. It was described from the Alps in Europe and reported from two localities (Umanak and Qags-siarssak) in western Greenland by Hansen, Poelt, & Sochting (1987). It should be sought in the North American Arctic.
Very similar to this but with larger spores, 18-19 x 6.5-7 µm, the septum 0.5-1 µm. and a yellow to yellow-orange thallus is Caloplaca laclea (Massal.) Zahlbr., a species known from south-central Europe, Norway, and Sweden and from Asuk, Greenland (Hansen, Poelt, & S0chting 1987). It may possibly occur in our range, as it occurs to the south in Alberta, Illinois, Michigan, Wisconsin, Indiana, Kansas, Colorado, and New Mexico.