Discovery of a new species Flaccisagitta yamato sp. nov. (Chaetognatha, Sagittoidea) and features of water circulation in the Yamato Rise region of the Sea of Japan

In the central Japan Sea, above the underwater Yamato Rise, chaetognaths (Chaetognatha, Sagittoidea) were discovered. Study of the anatomy of the specimens revealed the presence of saclike gelatinous structures (SG/S/), which indicates their belonging to the subfamily Flaccisagittinae. The features of the newly discovered species of Flaccisagitta are the distribution of fins on the body, the shape of the ciliated loop, the presence of peculiarly located ray structures and seminal vesicles relative to the caudal fin. The new species for science was named after the place of discovery above the Yamato Rise Flaccisagittayamato sp. nov. The uniqueness of the discovery lies in the distribution of the new species - it was found only in the waters above the Yamato Rise. Hydrological data are presented on a possible explanation of the distribution of the new species, its discovery in the central part of the Sea of Japan. Modern data on the movement of water masses obtained as a result of expeditionary research and observations from space are presented, which allow us to assume the reasons for the existence of this species above the Yamato Rise.