The examination of whole mounts prepared for transmission electron microscopy has resulted in the finding of thirteen taxa of nanoplanktonic coccolithophorids from the Weddell Sea, Antarctica. The material was collected as part of the AMERIEZ programme, March 1986. Cold-water adapted nanoplanktonic coccolithophorids have previously been shown to constitute a recurrent plankton element at subarctic and arctic localities. Three of the Weddell Sea species, Wigwamma annulifera, W. arctica, and Papposphaera sagittifera, are conspecific with northern hemisphere material, while two species, Calciarcus alaskensis and Turrisphaera arctica, are possibly identical with previously described arctidsubarctic material. Six taxa new to science have been described from the Weddell Sea, Wigwamma antarctica, W. triradiata, Trigonaspis melvillea, Pappomonas weddellensis, Papposphaera obpyramidalis, and P. simplicissima. The cooccurrence of identical forms at the two poles, and the fact that the species described are allocated to “arctic” genera, indicate a geologically relatively recent exchange of biological material between the poles.
