MICROHYPSIBIIDAE Pilato, 1998

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 : 43

MICROHYPSIBIIDAE Pilato, 1998

Minute eutardigrades without cephalic papillae. A paired elliptical organ may be present on the head ( Fig. 6 ). Diploclaws asymmetrically arranged with respect to the median plane of the legs (conventionally described as: 2121). The claws, of the Microhypsibius type, have a narrow basal section continuous with the primary branch; the secondary branch is rigidly joined to the primary branch at a distance from the base of the claw ( Figs. 1 C, 24A). The bucco-pharyngeal apparatus in the known genera has a rigid tube, without ventral lamina, but asymmetrical with respect to the frontal plane due to the differences in the shape between the dorsal and the ventral apophyses for the insertion of the stylet muscles ( Fig. 24 B–D). Both these apophyses have two very thin caudal processes pointing backwards and sideways. Peribuccal lamellae, and probably also peribuccal papulae, absent in the known species.

Composition: Only two genera are ascribed to the family: Fractonotus and Microhypsibius .

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 24. Claws and bucco-pharyngeal apparatuses of Microhypsibiidae. A, claws; B, bucco-pharyngeal apparatus of Microhypsibius; C, D, bucco-pharyngeal apparatus of Fractonotus (C, in dorsal view; D, in lateral view). ap = accessory points; bs = basal section; cp = caudal processes; da = dorsal apophysis; dlt = dorsal longitudinal thickening; pb = primary branch; sb = secondary branch: va = ventral apophyses. (from Pilato, 1998).