The Vychegda River was found for a new for the North-East of European Russia harpacticoid copepod (Copepoda: Harpacticoida) species Elaphoidella bidens in July, 2018. The species was identified in the discharge area of warmed sewage waters from the wood-processing enterprise. The species was found outside its habitation area with the northern border located in the temperate zone. The paper highlights its morphological, biological and ecological features in comparison with the other native representative of the genus – E. gracilis. By the comparison results of morphology among the Vychegda E. bidens and individuals from tropical populations and populations of the temperate zone, harpacticoids from the Vychegda River and from the Moscow region are highly similar. This similarity concerns antennae structure. The other morphological features considered as structure of body somites, swimming and rudimentary legs, caudal rami structure are common for representatives of every population.