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Bacidia illudens (Nyl.) Lynge
Family: Ramalinaceae
Bacidia illudens image
Thompson, J., 1997. American Arctic Lichens: The Microlichens.
Thallus white to ashy green, verrucose, scattered to thicker or lacking. Apothecia 0.5-0.7 mm or larger, appressed, the base constricted, flat, black, at first urceolate, becoming flat; margin thick to becoming thinner but persistent, very blue prui-nose; exciple reddish brown to violet tinged, and continuing into the hypothecium, which is also dark red-brown; epihymenium blue, turning violet with HN03; hymenium 65-70 µm, hyaline with the upper part blue, 1+ blue turning wine-red; paraphyses easily separable, slender, tips thickened to 4 µm; spores 8, bacillar, straight or slightly curved, 5-9-septate in the type specimen, but Lynge (1921) also noted down to 3-septate, 23-44 x 2.5-3 µm.

This species grows over moss and humus. In Scandinavia it has been reported on a wide variety of tree barks. Although possibly arctic-subarctic, it has been rarely collected in North America.