The biogeographical zonation of the Subantarctic region will be investigated, based on the presence of epifytic moss diatoms. The diatom communities that will be used in this survey, will be taken from moss collections, made on the different islands of this region. A similarity-analysis of the results should clarify whether the existing biogeographical zonations of the Subantarctic region (based on higher plants vertebrates) can also be adopted to protists, i.c. diatoms.