Pseudobiotus spinifer, a new tardigrade species (Eutardigrada : Hypsibiidae) from Nakdong River, South Korea, with a redescription of P. vladimiri Biserov, Dudichev & Biserova

A new freshwater tardigrade species, Pseudobiotus spinifer sp. nov., is described from the sand bottom of Nakdong River, South Korea. The new species is most similar to Pseudobiotus vladimiri from Biwa Lake, Japan, but differs from it by having small accessory points ending in the center of the primary branches of all claws, relatively longer claws and macroplacoids, and well developed cuticular spines/spicules over most of the dorsal and lateral surfaces of the body. Pseudobiotus vladimiri is redescribed on the basis of the holotype. A revised key to the species of the genus Pseudobiotus is also given.