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Abstract
The presentation of three distinct Neidium taxa from the sub-Antarctic and Maritime Antarctic region after examining more than 1500 samples from a broad variety of aquatic and terrestrial (micro-)habitats suggests that taxa representing the genus Neidium Pfitzer are not only quite rare in these regions, but that the three species also represent well-defined biogeographical distributions. N. nyvltii sp. nov., N. antarcticum sp. nov. and N. aubertii Manguin are characterized by linear to linear–lanceolate valves with rostrate to capitate apices, a single prominent longitudinal canal along the valve margins and lacinia covering the distal raphe endings. Neidium nyvltii is a benthic alkalophile growing in the Maritime Antarctic region under high total phosphorus (TP) and moderately high chloride concentrations, while the closest taxa for comparison (N. kozlowii Mereschkowsky and its varieties) are also alkalophilic, growing under lower TP concentrations in northern temperate–Arctic regions. Neidium aubertii is an acidophile with a sub-Antarctic distribution, whereas the most comparable taxa are N. bisulcatum (Lagestedt) Cleve, and N. bergii (A. Cleve-Euler) Krammer & Lange-Bertalot both are alkalophiles with northern hemisphere distribution and commonly occurring in the Arctic. There is some evidence of parallel similarities in valve forms between the polar northern and southern hemispheres. The significance of this parallelism is yet to be determined.
The authors wish to thank Niek J.M. Gremmen and Louis Beyens for the collection of samples on Heard, Prince Edward and South Georgia islands. Sampling on Crozet and Kerguelen has been made possible thanks to the logistic and financial support of the French Polar Institute-Paul-Emile Victor in the framework of the terrestrial program 136 (Marc Lebouvier & Yves Frenot). Samples on Byers Peninsula were taken in the framework of the IPY-Limnopolar Project POL2006-06635 (Ministerio de Ciencia y Tecnología, Spain). Sampling on Hurd Peninsula was made possible with the logistic support of the Bulgarian Antarctic Institute and within the contract 685/2005 with Ministry of Environment and Water (MOEW, Bulgaria). This study is also financially supported by a grant to PBH from the Canadian Museum of Nature. This study has been supported as a long-term research development project no. RVO 67985939 and project of Ministry of Education, Youth and Sports of the Czech Republic project Czech Polar LM2010009. Part of the research was funded by the following projects: MSMT KONTAKT ME 945 and ME 934. The authors would also like to thank the members of expeditions to the Czech J.G. Mendel Antarctic Station for field support and assistance. K. Kopalová benefited from an Erasmus grant during her stay in Belgium and GA UK grant nr. 394211. Part of the research was funded within the FWO project G.0533.07 and supported by L'Oréal-UNESCO ‘For Women in Science’ Program (Bulgaria) and an EU Synthesys grant to BVDV to visit the National History Museum in London, UK. Alex Ball, the staff of the EMMA laboratory and Eileen J. Cox at the Natural History Museum are thanked for their help with the scanning electron microscopy. The Olympus BX53 microscope used at the Faculty of Biology (University of Sofia) was bought with the support of the CEBDER Project (NSF, Bulgaria).