Both sexes of a new species of Sentiropsis Huys & Gee, 1996 (Copepoda, Harpacticoida, Pseudotachidiidae) are described from the upper sublittoral zone off Hyeopjae, Jeju Island, Korea. Sentiropsis coreana, new species is very similar to its zoogeographically closest congener, S. vietnamensis Gómez & Chertoprud, 2009 from Nha Trang Bay (Vietnam) in the South China Sea. Females of both species differ primarily in morphometric characters. The presence of a well-developed apophysis on the male P2 endopod of S. coreana serves to distinguish it from the Caribbean type species, S. minuta (Coull, 1973) and calls into question the previously suggested sister-group relationship between Sentiropsis and the Paradanielssenia-lineage characterized by the presence of claviform aesthetascs on the mouthparts. An updated key to the 19 valid genera of the subfamily Danielsseniinae is provided. The genus Carolinicola Huys & Thistle, 1989 is removed from the Pseudotachidiidae and transferred to the subfamily Hemimesochrinae in the Canthocamptidae.