EN
The locality of Potamogeton berchtoldii Fieber, the new species to the flora of Tajikistan (Middle Asia), together with its ecological conditions are presented. Additionally, the list of herbarium specimens of P. pusillus L. s. stricto gathered in Tajikistan and few specimens of P. berchtoldii collected from the area of adjacent countries are also provided. Taxonomical position of the species within the Potamogeton pusillus aggregation, the main morphological features of both taxa and possibility of finding other localities are discussed.