New European locality of <i>Gomphonema</i> <i>varians</i> (E. Reichardt & Levkov) and first record in Poland

The aim of this work is to indicate a new locality of Gomphonema varians in Poland, in the Kisielina River, together with photographic documentation under LM and SEM, and to compare the species with similar taxa from the Gomphonema genus like G. parvulum, G. micropus, and G. sarcophagus.The species often coexisting and may be confused and, consequently, misidentified.The research was carried out in 2023 in April and September at seven sites designated along a rivercourse in SE Poland.Findings indicate that G. varians prefers stagnant waters, mesotrophic to meso-eutrophic conditions, alkaline to neutral pH, and low electrical conductivity.