THE FIRST FINDING OF THE ORIENTAL RIVER PRAWN MACROBRACHIUM NIPPONENSE (DE HAAN, 1849) IN THE LOWER DON RIVER (AZOV SEA BASIN)

. In September 2019, in the lower reaches of the Don River, two specimens of a shrimp previously unknown for this river basin were recorded. The finding was made downstream of khutor Arpachin. The coordinates of the first finding location are as follows: N 47.258610°, E 40.166330°. The shape and armature of the rostrum, the proportions of the second pereopods, and a number of other morphological characteristics allowed the species to be identified as Macrobrachium nipponense (De Haan, 1849) (Decapoda, Crustacea, Palaemonidae). M. nipponense (De Haan, 1849), or oriental river prawn, is a subtropical shrimp, originated and widely distributed in Southeast Asia, including Japan, China, Republic of Korea, Vietnam, Myanmar and Taiwan. It is known that in the 1980–1990s in the temperate zones, this species was introduced into the cooling ponds of thermal power stations as a target of warm-water aquaculture. Several decades later, M. nipponense began to be observed outside the primary recipient reservoirs. The first findings of this genus were considered to be associated with long-distance migrations of this prawn. However, more recent data have shown that, at least in the south of the temperate zone, the prawns have formed stable populations outside warm water refugia. Finding of the oriental prawn in the Don River not only expands the known range of the species but also gives evidence for the continuation of the process of active expansion of M. nipponense through Eurasian water bodies.