The genus Nitzschia on the South Shetland Islands and James Ross Island

The purpose of this study was to present LM and SEM observations of Nitzschia taxa encountered on the South Shetland Islands and James Ross Island. During the ongoing taxonomical revision of the freshwater and limno-terrestrial diatom flora on the South Shetland Islands and James Ross Island (Maritime Antarctic Region) eight unknown taxa belonging to the genus Nitzschia were found. These taxa were previously force-fitted into European names such as N. commutata or N. perminuta, but detailed light and scanning electron microscopical observations allowed their separation from the already known taxa and resulted in the description of eight new species. The paper discusses all twelve Nitzschia taxa found in the Maritime Antarctic Region. New taxa are compared to the morphologically most similar taxa and their ecology and biogeography are discussed. Although the genus Nitzschia is present worldwide, a large number of Nitzschia taxa have a restricted distribution within the Antarctic Region, showing a clear bioregionalism.