Taxonomical re-investigation of Sarmatian diatoms from NE Bulgaria, hosted in the Pantocsek Collection (Budapest)

In the present paper, material collected from the vicinity of Balchik (NE Bulgaria) and housed in the Pantocsek Collection at the Hungarian Natural History Museum (Budapest) has been studied. Ten characteristic diatom species of regional and local importance were revised using scanning electron microscopy in order to clarify their identity. The purpose of the present paper is to elaborate on and photographically document the morphological variability of the examined taxa, and to compare the species composition with previously published data. The presence of Surirella comis Schmidt has been recognized for the first time from Bulgaria, as either fossil or recent form. Species characteristic for the association of the Achnathes baldjikii var. podolica Subzone have been indicated. Its stratigraphic range is within the Sarmatian Stage (Bessarabian Substage).