Abstract
Ohrid and Prespa lakes belong to a group of ancient lakes having an age of ca. 3 million years. Both lakes are characterized by a highly diverse diatom flora and endemism. Recent studies on the diatom flora led to the description of several new taxa. Observations on taxa closely related to the Sellaphora bacillum (Ehrenberg) Mereschkowsky complex showed the presence of two previously undescribed species. In this study, two new species, Sellaphora krsticii sp. nov. and Sellaphora perbacilloides sp. nov., are described. Furthermore a new combination, Sellaphora bacilloides (Hustedt) Levkov, Krstic & Nakov comb. nov. is proposed.