Diatoma bacillum sp. nov. from an artificial sandpit lake in Serbia

Diatoma bacillum Vidaković, Vlaović & Levkov sp. nov. is described from two hyposaline habitats in the Vojvodina Region, Serbia: the artificial sandpit lake ‘Peskara’ and the saline lake Pečena Slatina. The species was recorded on different substrates, including gravel, mud, and reed, with the highest relative abundance observed on reed at the type locality. Both habitats are shallow and alkaline, with pH values above 8, and are characterised by elevated salinity and sodium-bicarbonate dominance. The new species is described based on light and scanning electron microscopy. The taxon is characterised by linear valves with nearly parallel margins in larger specimens and linear to linear-elliptic valves in smaller specimens, broadly rounded, non-protracted apices, and distantly spaced primary ribs. These characteristics clearly distinguish it from morphologically similar species such as D. elongata, D. tenuis, D. problematica, and D. moniliformis.