Marine tardigrades from Lutzow-Holm Bay, East Antarctica with the description of a new species

• Published in: Polar Biology
• Main Authors: Fujimoto, S, Suzuki, AC, Ito, M, Tamura, T, Tsujimoto, M
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer-Verlag 2020
• Subjects: Biological Sciences; Evolutionary biology; Phylogeny and comparative analysis; Antarctic; The Antarctic; East Antarctica; Moreno; Renaud; Kristensen; Antarc*; Antarctica; Polar Biology
• Online Access: https://doi.org/10.1007/s00300-020-02671-w; http://ecite.utas.edu.au/143775

Marine tardigrades in the Antarctic and sub-Antarctic regions are poorly understood. During the 59th Japan Antarctic Research Expedition, a sediment sample was collected from Ltzow-Holm Bay, East Antarctica. The sediment sample yielded three species of marine tardigrades belonging to the family Styraconyxidae Kristensen & Renaud-Mornant, 1983: Angursa antarctica Villora-Moreno, 1998, Styraconyx cf. qivitoq Kristensen & Higgins, 1984, and S. takeshii sp. nov. The new species resembles S. nanoqsunguak Kristensen & Higgins, 1984 by the overall morphology, but the new species has thick seminal receptacle ducts that do not terminate in typical, swelled vesicles, in contrast to S. nanoqsunguak s narrow seminal receptacle ducts that terminate in small vesicles. The presence of the undivided mouth papilla and the larger body further differentiates the new species from S. nanoqsunguak . We also report a young adult female with a gonopore, but lacking seminal receptacles in the new species. As well as morphological information, we provided the sequences of the new species nuclear 28S rRNA and mitochondrial cytochrome c oxidase subunit I fragments. Using the former molecular data, phylogenetic analyses of Styraconyxidae were conducted and polyphyly of Styraconyx was suggested. The biogeography of marine tardigrades in the Antarctic and sub-Antarctic regions are also discussed.