Guadalupian (Middle Permian) megaspores from a permineralised peat in the Bainmedart Coal Measures, Prince Charles Mountains, Antarctica

A unique Guadalupian (mid-Permian) megaspore assemblage has been recovered from permineralised peats capping a coal seam in the Bainmedart Coal Measures, Prince Charles Mountains, East Antarctica. The megaspores are exquisitely preserved in three-dimensions and reveal the presence of at least three lycopsid species for which the macrofossil record is at present scant. The megaspores are assigned to three existing genera and in each case represent new species. Duosporites lambertensis sp. nov. and Banksisporites antarcticus sp. nov. are rare and predominantly laevigate trilete megaspores, but D. lambertensis sp. nov. has sparse grana or spinules and a shallow furrow bordering the contact faces, whereas B. antarcticus sp. nov. lacks ornament, has unmodified contact faces and has a more rounded amb. Singhisporites hystrix sp. nov. is the most abundant megaspore in the assemblage and is densely ornamented with elaborately branched, pointed processes. Scanning electron microscopy and X-ray synchrotron tomography reveal a spongy exosporium and no obvious mesosporium; microspores attributable to Lundbladispora sp. adhere to the ornament of S. hystrix sp. nov. these forms likely representing the microspores and megaspores, respectively, of the same biological species. Although of low diversity, the megaspore assemblage is of similar generic composition to those known from Permian sediments of the Mahanadi Graben, India, and appears typical of high-latitude Gondwanan Glossopteris-dominated peat-forming communities. This lends support to previous palaeogeographic reconstructions of Gondwana that place the Antarctic Lambert Graben as the southern (up-slope) extension of the Mahanadi Graben prior to dispersal of the southern continents. (C) 2011 Elsevier B.V. All rights reserved.