The diatom genus Stauroneis comprises far more species than actually known. This detailed morphological and taxonomical study of Stauroneis in samples from both the Arctic and (sub-)Antarctic Regions has resulted in the description of 40 new Stauroneis taxa. The 'catch-all' taxoa Stauroneis phoenicenteron, St. anceps and St. obtusa are thoroughly investigated and a lot of new (related) taxa are split off and described. Five taxa are only described provisionally, two from the Antarctic and two from the Arctic Region. It is possible that they represent also new species but more research on other populations should clarify their status. In total, 63 different Stauroneis taxa have been found. There is a clear separation in the genus Stauroneis between taxa occurring in the Arctic and taxa that have been found in the (sub-)Antarctic. Only five taxa ( St. gracilis, St. subgracilis, St. kriegeri, St. acuta and St. heinii ) have been found in both regions. Apart from these 5 taxa, 36 taxa have been found in the Arctic Region whereas the (sub-)Antarctic Region yielded another 20 taxa. This clear distinction between the Stauroneis composition of the two regions may contribute to the discussion about the cosmopolitan character and the biogeographical history of micro-organisms. Two species are described in this book from the Mediterranean Sardinia island and Central Europe respectively because they might be confused with the Arctic and/or (sub-)Antarctic taxa.weiterlesen