An undescribed taxon of the species-rich genus Nitocra was found during a survey on the harpacticoid copepods from the hyporheic zone in Vu Gia–Thu Bon Rriver, Central Vietnam. The new species, N. duyxuyenensis sp. nov., is morphologically similar to the American N. evergladensis Bruno & Reid, 2002. These two species can be separated by the number of marginal spinules on the anal operculum, the relative length of the baseoendopod of the female fifth leg, the structure of the antenna, the number of setae on the female fifth leg, the number of setae on the inner margin of the first endopodal segment of the second to fourth swimming legs of the males, and the number of setae on the third endopodal segment of the third swimming leg. Additionally, some comments on the groups and subgroups of the genus defined so far are given, with the proposal of the lacustris species subgroup for group III of Gómez et al. (2012).