Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus thin, forming yellowish pale patches on the rock or invisible. Apothecia to 1 mm broad, sessile with constricted base; margin lighter than disk, thin, rusty-reddish to deep orange; disk flat, dull, rust-red to darkened rusty red; hypothecium hyaline, oil-inspersed, 1+ blue; epihymenium reddish brown, granular, K+ violet; hymenium 85-90 µm, hyaline below, upper part reddish, 1+ blue; paraphyses coherent, tips not thickened; spores 8, polarilocular, ellipsoid, 10-17 x 5-6 µm, septum 2-3.5 µm.
This species grows on rocks and old bones, occasionally on old wood. It is circumpolar arctic.
C. arenaria differs from this in having smaller apothecia, 0.2-0.5 mm, concolorous disk and margins, and usually a narrow septum, 1.5-3 µm. Very similar to this also is C. leptocheila Magnusson, which has smaller apothecia, less than 0.5 mm, the margin and disk concolorous orange to rust-red instead of the margin lighter than the disk as in C. fraudans, and a similar 1+ blue excipular cortex, the spores being 13-15 X 4.5-6.5 µm, the septum 2.5-5.5 µm. C. leptocheila grows on noncalcareous rocks in Europe and Asia and was recently reported from Disko Island, Greenland, by Hansen, Poelt, & S0chting (1987). Also very similar is C. lithophila Magnusson, which has orange apothecia with I— excipular cortex, the spores 10-14 X 5-6.5 µm and septum 3-3.5 µm. This was reported from bird cliffs on Disko Island, Greenland, by Hansen, Poelt, & Sochting as var. elaeophora Hansen, Poelt, & S0chting with oil droplets in the upper paraphyses cells.