Integrative description of Hypsibius repentinus sp. nov. (Eutardigrada: Hypsibiidae) from Sweden

A new species of tardigrade from the genus Hypsibius Ehrenberg, 1848 is described from the bottom sediments of a small lake in the central part of Scandinavian Peninsula (Sweden), using an integrative approach, i.e. morphological techniques (light and scanning electron microscopy) combined with a molecular analysis (18S rRNA, 28S rRNA, ITS-2 and COI markers). Hypsibius repentinus sp. nov. belongs to the Hypsibius dujardini species–group and differs from the most similar species of this group in having a second macroplacoid with a definite constriction and in some other morphometric characters. Morphological diagnosis for the Hypsibius dujardini species–group is proposed, and its composition is discussed.