Deep-sea sipunculans (Sipuncula) of the northwestern Pacific

Based on the available literature data, museum collections, and our own material, a review is presented on sipunculan species of the northwestern Pacific that occur at depths greater than 500 m. Brief morphological descriptions showing the main characters used in taxonomy and a key for the identification of deep-sea sipunculans of the northwestern Pacific to species level are proposed. The key includes 22 valid species representing 7 genera and 5 families of Sipuncula.