Hypsibius vaskelae

Although H. vaskelae was found in a freshwater environment—specifically in dead leaves collected from the bottom of a small unnamed lake near the shoreline in the vicinity of Vaskelovo railway station in Leningrad Region, Russia—it is not considered a typical freshwater species. The shoreline of water bodies represents a transition zone between terrestrial and freshwater ecosystems, where species from both environments can be found.^[1]

The specimen was collected alongside other tardigrade species including Hypsibius cf. dujardini, Isohypsibius prosostomus, Isohypsibius sattleri, Diphascon cf. pingue, and Ramazzottius sp., with terrestrial species predominating in the sample. This suggests that H. vaskelae is more likely a semi-terrestrial species that accidentally entered the freshwater habitat, which aligns with the observation that most Hypsibius species are found in terrestrial environments.^[1]

At the time of tis original publication, H. vaskelae had only been reported from its type locality in Northwestern Russia. The rarity of this species and its disjunct distribution pattern compared to morphologically similar species might indicate a relict nature of this species complex.^[1]

Hypsibius vaskelae was formally described in 2018 by Denis Tumanov from the Department of Invertebrate Zoology at Saint Petersburg State University. The species name vaskelae is derived from Vaskela, the old Finnish name of the village Vaskelovo, where the species was discovered.^[1] It belongs to the genus Hypsibius within the family Hypsibiidae.^[2]

The species is most closely related to three other Hypsibius species that also have cuticular bars between the claw bases of their legs: H. marcelli (reported from Argentina), H. septulatus (reported from Peru), and H. shaanxiensis (reported from China). However, H. vaskelae differs from these related species in several morphological features, including its wrinkled dorsal cuticle, thinner claws, and the presence of lunules on the claws of all legs.^[1] The wrinkled dorsal cuticle and distinctive cuticular bars between claw bases are important taxonomic features, characteristics that are increasingly being used to refine tardigrade classification.^[3]