A review of Tabellaria species from freshwater environments in Europe

The diatom genus Tabellaria Ehrenberg is one of the most widely distributed genera in freshwaters, both in benthos and phytoplankton. It is rather frequent in unpolluted, circumneutral to slightly acidic and poorly mineralized lakes, streams and peat bogs. Despite being studied intensively in the last decades, the taxonomy of this genus is still unsatisfactory as some authors recently proposed to consider most species as synonyms of Tabellaria flocculosa (Roth) Kützing. Several dozen of Tabellaria rich samples from Europe were investigated and six were selected to illustrate typical populations. Five new species are described based on detailed LM and SEM observations: Tabellaria acidodelicata sp. nov., Tabellaria hercynica sp. nov., Tabellaria koppeniana sp. nov., Tabellaria procera sp. nov. and Tabellaria valdeventricosa sp. nov. Additionally, the type materials of T. fenestrata, T. flocculosa and T. ventricosa have been investigated and illustrated together with a discussion on Tabellaria andina stat. nov., at present exclusively found in South America.