A new genus and species, Pleijelius longae n. gen., n. sp., is proposed for a small hesionid from deep water off Woods Hole, in the Northwestern Atlantic Ocean. The new genus can be separated from other members of the family by having six pairs of enlarged anterior cirri, abundant dorsally-oriented notochaetae, provided with a single row of 2-4 denticles, and 10 cushion-shaped marginal pharynx papillae. A cladistic analysis indicates that this new taxon falls within Hesionidae and is the sister group to Hesioninae. A key to all ‘hesionid’ genera is also included.