The Hot Spot in a Cold Environment: Puzzling Parvodinium (Peridiniopsidaceae, Peridiniales) from the Polish Tatra Mountains.

Because of a great variety of remote localities and cold habitats, the Tatra Mountains are home to many freshwater protist lineages. Dinophytes have been subjected to a number of studies from this area dating mostly to the first half of the 20th century, but their true diversity remains elusive until today. We collected water tow samples at five lakes in the Tatra Mountains in order to establish monoclonal strains. We found four lineages that were distinctive in terms of morphology and DNA sequence data and that could be assigned to peridinialean Parvodinium. These four species can be readily distinguished based on a general shape, size, thecal plate tabulation pattern and presence or absence of an antapical protuberance. The plate overlap pattern is considered conserved at higher taxonomic levels, and the divergent keystone Plate 3' in Parvodinium marciniakii, sp. nov., thus appears as a striking diagnostic character. For taxonomic conclusion, we describe two species new to science and validate three old scientific names (i.e., one species and two varieties). Our study underlines that the biodiversity assessment, particularly of species adapted to cold environments, is anything but completed as shown from remote and unexplored European landscapes such as the Tatra Mountains.