What question did this study set out to answer?

To describe a new genus and species of deep-sea tardigrades from the family Euclavarctinae.

February 19, 2026Journal of the Marine Biological Association of the United Kingdom0 citations

A new genus and species of Tardigrada (Halechiniscidae: Euclavarctinae) from the deep sea of Okinawa Islands, Japan

SFShinta FujimotoYamaguchi University HYHiroshi YamasakiKyushu University SOSusumu OhtsukaHiroshima University

Key Points

To describe a new genus and species of deep-sea tardigrades from the family Euclavarctinae.
Sediment sample collection from the deep sea off Kuroshima island, Okinawa, Japan.
Taxonomic classification based on morphological characteristics.
Comparison with existing species within the subfamily Euclavarctinae.
Introduction of Ranarctus kondoi as a new genus and species.
Distinct morphological features include aliform expansions and a trapezoid head.
Differences from related species are noted in the structure of cirri and digits.

Abstract

Abstract Marine tardigrades are known from all oceans. However, Euclavarctinae (Halechiniscidae) is the only family-group taxon exclusive to the deep sea. We describe a new genus and species of this taxon, Ranarctus kondoi gen. et sp. nov. The new genus and species was sorted from a sediment sample collected at a locality north of Kuroshima island, Kerama Islands, Okinawa, Japan (water depth: 596–606 m) during a T/RV Toyoshiomaru cruise (Hiroshima University) in 2003. It does not completely conform to the subfamily’s diagnosis as in the case of Parmursa by its aliform expansions, trapezoid head, and primary clava and lateral cirrus sharing a common pedestal. Aside from these similarities, Ranarctus gen. nov. differs from Parmursa by its wrinkled aliform expansions lacking ribs, cephalic cirri’s constant-width scapi, and internal digits longer than external ones. ZooBank LSID: urn:lsid:zoobank.org:pub:F096F6D5-0A25-4E99-8258-767550931186 .

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