Diagnosis. Thallus areolate, orange (Flame Scarlet to Orange Chrome) especially around soralia, no prothallus; areoles convex, 0.1–0.5 mm diam. Soralia from centers of areoles, round, mostly filling areoles, eroding or not, 0.1–0.3 mm diam., soredia orange (Orange Chrome). Thallus cortex thin, algae almost to surface 10.0–20.0 µm thick, no necral layer. Apothecia rare, scattered, round, flat, 0.4 µm diam., disk orange (Orange chrome), proper margin flush, thin, thalline margin not evident. Epihymenium golden, hymenium 56–60 µm, small round cells below hymenium, apothecial margin with small round cells, algae only at base, tips of paraphyses not swollen, no branches. Asci with 8 spores, spores with two locules, 11.0–14.0 3 7.0 µm, isthmus 4.0 µm. Pycnidia not seen. Thallus and apothecium K+ red, C-, epihymenium K+ red, C-.
Taxonomic notes.The most important characters of this species are the discrete convex areoles and the soralia developing in the centers of the areoles (Fig. 11). The soralia soon enlarge to fill the entire areoles. It has been confused with C. chrysophthalma, but that species has a yellow orange thallus, the areoles are larger, and it has a more temperate distribution. Some specimens on rock were identified as C. cirrochroa (Ach.) Th. Fr., but that species has elongate lobes.
Ecology and distribution.This species occurs on both wood and bark and on rock in the high Arctic. It is known only from scattered localities in northern Alaska (Fig. 2) but it might also be found in the high Arctic of Canada.