Taxonomy and distribution of deep benthos collected in and around the Southern Ocean during the 30th Anniversary expeditions of R/V Hakuho Maru: Annelida, Mollusca, Ostracoda, Decapoda, and Echinodermata

The Southern Ocean is widely recognized for its unique benthic ecosystems, but benthic sampling has been largely restricted to shallower continental zones and much remains to be learned about the biodiversity in the bathyal and abyssal zones. In this study, we collected and investigated the deep-sea benthic habitat using geological dredges, a multiple corer, and a bait trap on-board the R/V Hakuho Maru in bathyal to abyssal depths between the latitude of 39°38.16′S–66°36.03′S and the longitude of 62°19.55′W–67°37.95′E in the Southern Ocean and the surrounding subantarctic region, focusing on West Antarctica. We carried out 20 geological dredges, 14 multiple corers, and a bait trap survey. Here, we present the taxonomic and distributional records of 180 species of Annelida, Mollusca, Ostracoda, Decapoda, and Echinodermata identified from our samples, including species-level identifications and detailed occurrence information where possible. Although West Antarctica is a highly investigated area for benthic biodiversity around Antarctica, our collection includes the annelid Flabelligena hakuhoae Jimi et al. 2020 which was new to science at the time of collection, and other potentially undescribed species of Annelida, Ostracoda, Asteroidea, and Holothuroidea. Several specimens collected updated the distribution ranges of their species.