Rare diatom Stauroneis balatonis Pantocsek recorded in Lake Savsko, Serbia

Although well represented in the fossil diatom flora throughout Europe and Asia, from the early-middle Miocene to the Quaternary, Stauroneis balatonis is considered a very rare diatom with a contemporary distribution limited to two ancient lakes – Ohrid and Prespa. The objective of this study was to describe the first finding of S. balatonis in Serbia in Lake Savsko and to update information on the distribution and ecology of this rare species. Periphyton samples were collected from artificial substrates incubated at three depths (0.5 m, 0.8 m and 1.4 m) in Lake Savsko and the epilithic community was sampled in the littoral zone. Samples were collected weekly in summer 2014, from mid-July to mid-September. Diatom permanent slides were prepared and small numbers of S. balatonis specimens were observed only in samples collected in September from artificial substrates incubated at the greatest depth (1.4 m). Our results significantly contribute to the information on the contemporary distribution and the ecology of this rare diatom taxon, especially considering the fact that S. balatonis specimens were observed in our study in diatom communities developed on artificial substrates and in an urban reservoir, i.e. Lake Savsko.