Three new Hantzschia species (Bacillariophyta) from the Maritime Antarctic Region

Following an earlier revision of the genus Hantzschia (Bacillariophyta) in the Maritime Antarctic Region, several at present unidentified or poorly known taxa of this aerophilic genus have been investigated using both light and scanning electron microscopy. Based on the morphological analysis of the observations, three new species are currently described: Hantzschia australabundans sp. nov., H. zidarovae sp. nov. and H. zikmundiana sp. nov. The new species differ from comparable taxa in valve outline, structure of the internal proximal raphe endings and structure of the striae and areolae. Additional observations are presented on Hantzschia amphioxys and its forma muelleri, H. abundans and H. incognita, based on observations of Antarctic populations from the South Shetland Islands, Vega Island and James Ross Island. Brief notes on the ecology of all reported species are added.