The evolution and distribution of Calyptozetes sarekensis (Acari: Oribatei)
1979
SEYD, EDMUND L.
Calyptozetes sarekensis, an oribatid mite found predominantly, though not exclusively in lichens, inhabits regions within the arctic circle and subarctically between latitudes 60o and 70o (Swedish Lapland, Norway, Bear Island, Spitzbergen, Jan Mayen, Iceland, Greenland, northern Canada). In recent years, however, the species has been recorded from a number of montane sites in Great Britain and southern Europe. There would appear to be only two possible explanations for die discontinuous distribution of this mite. (1) The species has been transported from its main arctic and subarctic area of distribution to its southern montane outposts by some agent (driftwood, birds, wind), or (2) in Britain and southern Europe it represents a relict species of the Ice Age, left stranded on high ground after the final retreat of the ice. Evidence is presented in support of the second hypothesis. In addition, it is suggested that its presence on the different land masses of its main arctic and subarctic range, which are separated from each other by wide stretches of ocean, could be explained by die hypothesis that it is a very ancient species daring from the time Laurasia was in existence some 60 or more million years ago. The alternative hypothesis of transportation of the species between one or more of these areas, however, is by no means ruled out.
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