Four new species of the Diphascon nobilei group (Eutardigrada, Hypsibiidae)

The existence of a group of species similar to Diphascon (Diphascon) nobilei is shown. These species have some common characteristics: a well-evident drop-shaped thickening between the buccal tube and the pharyngeal tube, pharyngeal bulb, more or less elongate, with three rod-shaped macroplacoids and microplacoid, claws of the hind legs different from those of the first three pairs of legs in having a very wide basal portion and indented basal margin, basal spurs also present on the external claws and, in some cases, also on the internal claws of the first three pairs of legs. Four new species of this group are described: Diphascon (D.) serratum, D. (D.) nelsonae, D. (D.) platyungue, and D. (D.) hydrophilum. They differ from one another in the dimensions and shape of the claws; in some cases the difference also affects the value of the ptd index relative to the insertion point of the stylet supports, the buccal and the pharyngeal tube length or the macroplacoid length.