Lepraria atlantica Orange
Nomenclatural data
Lichenologist 33: 462 (2001)
Material from Greenland is leprose, diffuse, soft, powdery, sometimes almost cottony; light grey to whitish, often greenish; soredia medium sized, sometimes coarse and of the same size as those of L. alpina, usually with short projecting hyphae; medulla often distinct.
L. atlantica was described as chemically identical to L. alpina (Orange 2001). In Greenland four chemotypes are recorded: (1) with atranorin, porphyrilic and roccellic/angardianic acids (n = 6); (2) with atranorin, porphyrilic and rangiformic acids (n = 6); (3) with atranorin, porphyrilic acid and both fatty acids, roccellic/angardianic and rangiformic acids (n = 1); (4) with porphyrilic acid only, often in small amounts (n = 17).
L. atlantica morphologically resembles most closely L. jackii. In Greenland the latter has a more cottony thallus, of a looser consistence. Chemically, these two species are different as L. atlantica produces porphyrilic acid unlike L. jackii.
Some specimens are morphologically intermediate between L. atlantica and L. alpina, notably most of them belong to chemotype (4) with only porphyrilic acid in the thallus. The absence of atranorin and fatty acids in chemotype (4) may depend on the overall low concentration of secondary substances in these specimens or it may still be a distinct chemotype. See also the discussion under L. alpina.
Ecology and distribution

On soil and bryophytes, sometimes overgrowing other lichens, rarely on rocks.
Reported here as new to Greenland. L. atlantica has a relatively rather wide distribution in Greenland being more frequent in the Low Arctic and the Qeqertarsuaq (Disko) area.
Saag, L., Hansen, E. S., Saag, A. & Randlane, T. 2007.