Four new monoraphid diatom species (Bacillariophyta, Achnanthaceae) from the Maritime Antarctic Region

Four monoraphid taxa belonging to the genera Achnanthes, Psammothidium and Planothidium were found during the ongoing taxonomic revision of the freshwater and limno-terrestrial diatoms of the Maritime Antarctic region. The present paper describes these four taxa as new based on detailed light and scanning electron microscopy observations: Achnanthes kohleriana Kopalová, Zidarova & Van de Vijver sp. nov., Planothidium wetzelectorianum Kopalová, Zidarova & Van de Vijver sp. nov., Psammothidium confusoneglectum Kopalová, Zidarova & Van de Vijver sp. nov. and Psammothidium superpapilio Kopalová, Zidarova & Van de Vijver sp. nov. The morphology and ecology of all four taxa are discussed and the species are compared with morphologically similar taxa.