New Species of the Genus Richtersius Pilato & Binda, 1989 (Tardigrada: Eutardigrada: Richtersiusidae) from Uzbekistan

Anew tardigrade species from the family Richtersiusidae, Richtersius mazepi sp. nov., from Uzbekistan, is described and illustrated. A comparison to all three of the previously described congeners revealed a unique set of morphological characteristics of the egg ornaments, which makes the new species clearly distinct from the others. The unique characteristics are as follows: (i) the presence of light-refracting dots or pores and a crown of thickenings around the base of the egg processes; (ii) the presence of dark dots on the egg surface between the processes; (iii) a labyrinthine layer seen as light-refracting dots in the wall of the proximal portion of the egg processes; and (iv) egg processes comprised of a wide dome-shaped proximal portion and an elongated slender distal portion. The new species discovered in this study constitutes the fourth formally described species within the genus Richtersius Pilato & Binda, 1989. The issue concerning the use of a classical taxonomic description based on morphological data is also discussed.