Lepraria caesiella R.C. Harris
Nomenclatural data
in Lendemer, Opuscula Philolichenum 2: 51 (2005)
Pale bluish grey (fades to white in the herbarium), poorly delimited, consisting of loosely to densely packed soredia/consoredia without medulla and prothallus, initially of scattered soredia/consoredia, then forming small patches which fuse to form extensive, irregular, ± continuous thalli, rather thin, 0.1–0.2 mm thick; soredia 20–30 µm in diam., filled with small crystals, with short, irregular, projecting hyphae, 25–30 µm long; consoredia to 100 µm in diam. (after Lendemer 2005).
Greenland specimens that were assigned to this species had slightly larger soredia (up to 65 µm in diam.) and slightly shorter projecting hyphae; otherwise they correspond to this description.
All four specimens contain atranorin and zeorin, two of them have roccellic acid as an accessory. Roccellic acid was not reported in original description by Lendemer (2005).
L. caesiella was recently described from North America, but was known earlier as “Lepraria sp. 3” (Harris 1977). Its most distinctive feature is the chemical content comprising atranorin and zeorin and lacking divaricatic acid; otherwise it is stated to be rather similar to L. incana (L.) Ach. The Greenland specimens resemble a relatively densely packed morph of L. incana, still being a bit paler. L. incana can be morphologically quite variable, sometimes forming relatively loose cottony cushions and sometimes consisting of sparse or denser separate soredia only.
Ecology and distribution

On soil and bryophytes.
L. caesiella is reported here as new to Greenland. It is confined to the Low Arctic (one locality is situated on the border with the High Arctic). Elsewhere it is common in the eastern USA and Canada.
Saag, L., Hansen, E. S., Saag, A. & Randlane, T. 2007.