Hypsibius Ehrenberg 1848

Hypsibius sp.

Material examined: One specimen from site 1, body length 171 µm.

Remarks: This single specimen is poorly preserved and oriented so that an adequate description is not

possible. But it is remarkable in that only a very small number of marine eutardigrades are known. The genus Halobiotus Kristensen, 1982 is secondarily adapted to saltwater environments in northern latitudes, as is, apparently, Thulinius itoi Tsurusaki, 1980. All were described from intertidal or supralittoral sand. Our specimen was found in sand at 3 m depth, over 2000 m from the nearest shore. Is it a truly marine species or a terrestrial species that was an “accidental” in these samples? The distance from shore might suggest the former hypothesis, while the lone occurrence supports the latter. The specimen has a granulated cuticle without gibbosities, no visible eyes, Hypsibius - type claws with thick primary branches and well-developed accessory points, light refracting areas at the base of primary branches of all claws, lack of claw lunules, and a pharynx with two small macroplacoids (the first pear-shaped and larger than the second) and a minute roundish microplacoid/septula. Together with some morphometric characters, this does not match any currently known Hypsibius species. It seems to us improbable that an accidental terrestrial specimen would also be a species never before encountered. Further sampling is needed to resolve this intriguing question.