In July 2018, in the estuary area of the Sura River (a tributary of the first order of the Cheboksary reservoir, Nizhny Novgorod oblast, Russia) was record a tropical alien co-pepod Thermocyclops taihokuensis Harada, 1931 (Copepoda: Cyclopoida). Information about the discovery of this species in the European part of Russia is extremely scarce. There is only one report of the discovery of this species in the lower reaches of the Volga River. The main habitat of T. taihokuensis is distributed in East and Central Asia, as well as tropical regions. The paper presents a brief description of T. taihokuensis with updated drawings. The records in the estuarine area of the Sura River T. taihokuensis females had an average size of 1060±20 pm. The spread of tropical crustaceans beyond their natural habitat appears to be linked to human activities and the transport of ballast water by ships. In addition, the concept of zoochoria suggests that the settlement of this species may be associated with the transfer of resting stages of T. taihokuensis by migratory species of waterfowl. Thus, migration routes of various bird species from the Arctic and temperate climatic zones to subtropical and tropical regions pass over European Russia. Alien species have high phenotypic and ecological plasticity and are able to introduce ecosystems into imbalance. That is why new studies of the Sura River and the Cheboksary reservoir will help not only to judge the success of the naturalization of T. taihokuensis, but also about the environmental consequences of the penetration of this species into the territory of the European part of Russia.