HYPSIBIIDAE Pilato, 1969

Pilato, Giovanni & Binda, Maria Grazia, 2010, Definition of families, subfamilies, genera and subgenera of the Eutardigrada, and keys to their identification, Zootaxa 2404, pp. 1-54 : 19

HYPSIBIIDAE Pilato, 1969

Eutardigrades without cephalic papillae. A paired elliptical organ may be (rarely) present on the head ( Fig. 6 ). The two diploclaws of each leg, usually different in the shape and size, are asymmetrically arranged with respect to the median plane of the leg (conventionally described as: 2121). Each diploclaw has a basal section which is continuous with the secondary branch, and a primary branch that is joined through a relatively flexible connection ( Fig. 1 E). Only exceptionally the main branch appears rigidly joined to the secondary branch or quite separated from it. Many types of bucco-pharyngeal apparatuses can be distinguished; when peribuccal structures are present, the sagittal plane passes between those structures.

Types of claws. Many types of claws can be recognized within the family.

The Isohypsibius type ( Fig. 10 A)

The secondary branch and the basal section form an almost right angle. Diploclaws of the same leg are slightly different in the size and shape from each another.

The Ramazzottius (= oberhaeuseri ) type ( Fig. 10 C)

Diploclaws of the same leg extremely different from one another in the size and shape. External claws with basal section longer than the secondary branch; primary branch very long and slender; internal claws short and stout.

Figures

FIGURE 1. Some types of claws of the Eutardigrada. A, Milnesiidae; B, Hexapodibius (Calohypsibiidae); C, Microhypsibiidae; D, Eohypsibiidae; E, Hypsibiu s (Hypsibiidae); F, Macrobiotus (Macrobiotidae). ap = accessory points; bs = basal section; bth = basal thickening; ds = distal section; lu = lunula; pb = primary brach; s = stem; sb = secondary branch; sp = spur. (B, from Binda & Pilato, 1969; C, from Pilato, 1998).

FIGURE 6. Paired elliptical organ present in some Calohypsibiidae, in some Hypsibiidae and some Microhypsibiidae. eo = elliptical organ.

FIGURE 10. Claws of Hypsibiidae. A, Isohypsibius type; B, Hypsibius type; C, Ramazzottius type. (A, from Binda & Pilato, 1971; B, from Binda & Pilato, 1985; C, from Pilato & Rebecchi, 1992).