Lepraria eburnea J.R. Laundon
Nomenclatural data
Lichenologist 24: 331 (1992)
Lepraria frigida J.R. Laundon, The Lichenologist 24: 332 (1992)
Leprose, powdery, often cottony, soft, usually thick; white to light grey, often cream or slightly greenish, sometimes with rose tinge (herbarium specimens, caused by alectorialic acid); thallus margin diffuse, rarely delimited; medulla distinct, white; soredia loosely packed, variably sized, mostly coarse, usually with short projecting hyphae.
Three main chemotypes were described in L. eburnea by Orange (1997): (I) with alectorialic and protocetraric acids; (II) with alectorialic, psoromic and 2’-O-demethylpsoromic acids; (III) with alectorialic acid only. In Greenland also three chemotypes can be separated: (1) with alectorialic and protocetraric acids, (chemotype I sensu Orange 1997) (n = 1); (2) with alectorialic and roccellic/angardianic acids (n = 2); (3) with alectorialic acid only (chemotype III sensu Orange 1997) (n = 11).
L. frigida, earlier reported from Greenland by Hansen (2002b), was synonymized with L. eburnea by Orange (1997). The detection of protocetraric acid in some specimens of L. frigida, including its holotype, demonstrated a chemical continuity between L. frigida and L. eburnea – the protocetraric acid concentration ranging from trace to major. Orange (1997) also pointed out the close morphological resemblance between these species which had already been discussed by Laundon (1992).
L. eburnea often has a thick, soft and cottony appearance. In Greenland, however, thalli are usually a bit more densely packed, a few being almost granular, but still clearly different from the chemically similar L. neglecta. Alectorialic acid is considered a diagnostic substance in both these taxa
Ecology and distribution

On soil and bryophytes, sometimes overgrowing other lichens, rarely on rocks.
Although not numerous, L. eburnea is rather widely distributed, being more frequent in the Low Arctic and absent from the southern- and northernmost parts of the territory.
Saag, L., Hansen, E. S., Saag, A. & Randlane, T. 2007.