A new occurrence of dinocysts Pseudokomewuia in continental Cenosoic (Oligocene–Miocene) rocks of the West Siberian plain is identified. A complex of palynomorphs with dominant microphytoplankton (dinocysts) was found for the first time in the lacustrine-marsh sediments of the south of Tyumen oblast. The variable composition of the complex with Pseudokomewuia aff. laevigata He and Pseudokomewuia aff. granulata He species is traced upward through the section. The layers that correspond to the maximum abundance of Pseudokomewuia (akme) are distinguished and correlated with sections studied previously, which are located in the Barabinsk lithofacial region. Sediments with dinocysts are compared with sediments of the same age from North America, Northern Europe, and Southern China.