Marine Biodiversity

, Volume 49, Issue 5, pp 2445–2454 | Cite as

A new genus and species of Stygarctidae (Heterotardigrada: Arthrotardigrada) from Yaku-Shin-Sone bank (Northwest Pacific)

  • Shinta FujimotoEmail author
  • Susumu Ohtsuka
Original Paper


A marine armoured tardigrade, Hansenarctus toyoshiomaruae gen. et sp. nov., is described from Yaku-Shin-Sone bank, south of Yakushima island, Northwest Pacific. It belongs to the family Stygarctidae Schulz, 1951 for its five-lobed head, cuticular plates, and non-digitate claws, but a combination of the following character states warrants the erection of the new genus: the semi-globular secondary clavae, sub-divided lateral lobes of the head, antero-dorsal, postero-dorsal, and latero-dorsal processes on the dorsal plates except for the caudal plate, two tapering lateral processes (one pair) on each body plate, four lateral processes (two pairs) on the caudal plate, intersegmental regions between dorsal plates, looped seminal receptacles without additional cuticular structures at the openings, and four claws with the internal ones bearing dorsal spurs. Its phylogenetic position is briefly discussed based on morphology and the following topology was suggested for Stygarctidae: (Megastygarctides, (Neostygarctus, (Faroestygarctus, Hansenarctus gen. nov., (Mesostygarctus, Pseudostygarctus), (Parastygarctus, Prostygarctus, Stygarctus)))). Stygarctid genera (excluding Megastygarctides and Neostygarctus) share a synapomorphic state: the presence of exteriorly projected apophyses in the pharyngeal bulb.


Japan Marine meiofauna Phylogeny Systematics Tardigrada 



We thank the captain and crew of TR/V Toyoshiomaru of Hiroshima University and the research members of the cruise no. 2016-25 for their assistance in collection on board.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All applicable international, national, and/or institutional guidelines for the care and use of animals were followed by the authors.

Sampling and field studies

All necessary permits for sampling and observational field studies have been obtained by the authors from the competent authorities.

Data availability

The material observed in this study, KUZ Z2161 and KUZ Z2162, is deposited in the Zoological Collection of Kyoto University.


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Copyright information

© Senckenberg Gesellschaft für Naturforschung 2019

Authors and Affiliations

  1. 1.Research Center for Marine Biology, Graduate School of Life SciencesTohoku UniversityAomoriJapan
  2. 2.Takehara Station, Setouchi Field Science Center, Graduate School of Integrated Sciences for LifeHiroshima UniversityHiroshimaJapan

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