Abstract
Five unknown taxa belonging to the newly established genus Humidophila were found during ongoing taxonomic revision of the freshwater and limno-terrestrial diatom flora of the Maritime Antarctic Region. These taxa were previously identified as Diadesmisarcuata, D.biscutella, D.comperei and D.ingeae, but detailed light and scanning electron microscopy observations allowed their clear separation from the already known taxa, and resulted in the description of five new species: Humidophilasceppacuerciae Kopalova sp.nov., H.australoshetlandica Kopalova, Zidarova & Van de Vijver sp.nov., H.keiliorum Kopalova sp.nov., H.deceptionensis Kopalova, Zidarova & Van de Vijver sp.nov. and H.vojtajarosikii Kopalova sp.nov.
All five new taxa are compared with the morphologically most similar taxa, and their ecology and biogeography are discussed. Although the genus Humidophila is present worldwide, a large number of Humidophila taxa have a restricted distribution within the (sub-)Antarctic Region, showing a clear bioregionalism.