Deep-sea spoon worms (Echiura) from the Sea of Okhotsk and the adjacent slope of the Kuril-Kamchatka Trench

Abstract

During the SokhoBio (Sea of Okhotsk Biodiversity Studies) expedition from July to August 2015, eleven sites across the Kuril Basin of the Sea of Okhotsk and the landward abyssal slope of the Kuril-Kamchatka Trench (KKT) off the Bussol Strait were surveyed and benthic communities were investigated. Samples comprised 260 echiurans from seven species of seven genera belonging to the family Bonelliidae, were collected at eight of the eleven sites of the SokhoBio expedition. The family Bonelliidae is most common in abyssal and hadal environments in the world ocean with high abundances in all investigated regions. The description of deep-water echiurans from the Sea of Okhotsk is the first one based on complete collected specimens with living colouration. The descriptions provide new information on the morphology and taxonomic details of the species, which were previously noted from the northwestern Pacific and described from damaged or incomplete specimens. Two species are identified as representatives of the two genera, Bengalus and Bonelliopsis, which never have been noted before in the northwestern Pacific and the genus Bengalus is reported for the first time in the Pacific. The knowledge of the geographic ranges of these genera are expanded and discussed.