Notahypsibius arcticus Tumanov 2020, gen. et comb. nov.

• Main Author: Tumanov, Denis V.
• Format: Other/Unknown Material
• Language: unknown
• Published: 2020
• Subjects: Biodiversity; Taxonomy; Animalia; Tardigrada; Eutardigrada; Parachela; Hypsibiidae; Notahypsibius; Notahypsibius arcticus; Acutuncus antarcticus; Antarc*; antarcticus; Franz Joseph Land; Macrobiotus arcticus
• Online Access: https://zenodo.org/record/4328816; https://doi.org/10.5281/zenodo.4328816

Notahypsibius arcticus (Murray, 1907) gen. et comb. nov. Macrobiotus arcticus Murray, 1907b: 677, pl. 1, fig. 5a–f (description). Macrobiotus heinisi Richters, 1911: 15, fig. 15. Hypsibius arcticus – Thulin 1911: 27. — Marcus 1930: 380. — Dastych 1991: 141–159 (taxonomical notes). Ramazzottius arcticus Gąsiorek et al. 2018: 52. Type locality Franz Joseph Land (Murray 1907b). Notes The species Hypsibius arcticus (Murray, 1907) was recently transferred by Gąsiorek et al. (2018) to the genus Ramazzottius on the basis of having Ramazzottius -like claws and freely laid eggs. In my opinion, the type of the chorion ornamentation in this species, consisting of the internal pillars, is definitely different from the external processes that are typical of the genus Ramazzottius (see Discussion). The combination of the Ramazzottius -like claws and eggs with developed internal pillars in the egg chorion makes this species more similar to N. pallidoides gen. et comb. nov. It should, therefore, be transferred to the new genus as Notahypsibius arcticus gen. et comb. nov. This species differs from N. pallidoides gen. et comb. nov. by having better developed pillars in the egg chorion and by laying free eggs. However, the latter trait requires confirmation as it is assumed upon the basis of a single observation (Murray 1907b), especially taking into consideration that Macrobiotus heinisi (Richters, 1911) – a similar species described from the same locality (Franz Joseph Land) and later synonymized with H. arcticus (Marcus 1930) – has eggs with a similar chorion structure laid within the exuvium (Richters 1911). Also, Acutuncus antarcticus, which shares an eggshell structure of a similar appearance, is known to lay eggs both within the exuvium and freely (Dastych 1991; pers. obs.). Other key characteristics, such as the presence of the minute septulum and cuticular sculpture, may have been overlooked by Murray (1907b) in his original description, as visualisation of these structures requires the use of high quality optics ...