As a result of studying different populations of crustaceans of the genus Eurytemora Giesbrecht from the inland water bodies of the basins of the White Sea, the Pechora Sea, the Lena River delta, and Pacific coast of the United States, the species Eurytemora gracilicauda Akatova 1949 has been found along the entire northern border of the Russian Eurasia, while North American E. americana Williams 1906 has not been registered within these limits. Clear morphological and molecular genetic differences between E. gracilicauda and E. americana are presented.