Аннотация:Phoronids are benthic marine invertebrates from the Lophophorata clade. They have a worldwide distribution and can form dense benthic aggregations, where they act as ecosystem engineers. Paraffin histology,serial sectioning, scanning electron microscopy, and 3D reconstructions are used to describe and identify phoronids, which have been collected in the Sea of Okhotsk from up to 1551 m depth. Identified speciesbelongs to Phoronopsis genera based on the presence of epidermal fold (a collar) at the base of the lophophore. The lophophore is transitional to spiral, number of tentacles is 120-150. Longitudinal muscles are feather-like; there is a single left giant nerve fiber. Species is dioecious, oocytes are mature in May, lophophoral organs are small and membranous. Metanephridia have ascending and descending branches of canal and one funnel, that opens in both oral and anal coelomic chambers. Morphological descriptionof deep-sea phoronids cannot be fully attributed to known phoronid species. As before phoronids were found only on depths not exceeding 400 meters, this discovery is the first phoronid living on depth up to 1.5 km and the first record of phoronids in the basin of Sea of Okhotsk. Our research aids in the effort of documenting phoronid diversity, distribution, and ecology. The study is supported by Russian Science Foundation (#18-14-00082).
