A new interstitial hoplonemertean, Ototyphlonemertes dolichobasis sp. nov., is described from Otsuchi Bay, Iwate Prefecture, on the Pacific coast of northern Honshu Island, Japan. The new species can be distinguished from all its congeners by its extremely long central stylet basis, 286 mu m on average, which is more than three times the known maximum length in the genus. The shape of the central stylet, which is streamlined with two gently intertwined strands, is also distinctive.