Leg and claw adaptations in soil tardigrades, with erection of two new genera of Eutardigrada, Macrobiotidae: Pseudohexapodibius and Xerobiotus

We interpret reduction of the claws on the fourth pair of legs as a convergent adaptation of interstitial soil-dwelling tardigrades. The eutardigrades Hexapodibius degenerans, Macrobiotus pseudohufelandi, and M. xerophilus are re-examined and H. degenerans re-described. Due to the absence of true claws on the fourth pair of legs and to the symmetry of its claws on the first three pairs of legs, H. degenerans is attributed to a new genus, Pseudohexapodibius, belonging to the family Macrobiotidae. On the basis of the peculiar type of claws, without a distinct peduncle, M. pseudohufelandi and M. xerophilus are attributed to another new genus of Macrobiotidae, Xerobiotus.