substrate: wood dead, living | rock siliceous, siliciferous, acidic | rock, stones, pebbles unspecified.
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus thin, grayish or blackish, granu-lose to disappearing; sometimes with thin whitish hypothallus, K—. Apothecia small, to 0.8 mm broad; margin of same color as thallus, soon disappearing; proper exciple of same color as disk or slightly paler; disk concave to flat and then convex; hypothecium hyaline or yellowish, with oil globules; epihymenium yellow or greenish yellow, granulose, K+ purple; hymenium 60-90 µm, hyaline; paraphyses simple or branching above, tips capitate, 3-5 µm; spores ellipsoid or ovate, polarilocular, 10-16 X 5-8 µm, septum 3-5 µm.
This species grows on the bark of woody plants, old wood, and occasionally on rocks. It is temperate to arctic-boreal, in western North America, ranging south to California and Arizona.
Hansen, Poelt, & S0chting (1987) have treated material of this same sort from Greenland on wood as C. pyracea, stating that it did not appear sensible to them to use the name C. holocarpa, which in their opinion was a temperate zone bark- and wood-inhabiting species. In North America, as the map shows, however, there seems no real hiatus between the temperate and arctic ranges. More study of the C. pyracea group seems needed.