CALOHYPSIBIIDAE 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 : 12-13

CALOHYPSIBIIDAE Pilato, 1969 (amended by Pilato, 1989)

Eutardigrades without cephalic papillae. A paired elliptical organ may be present on the head ( Fig. 6 ). Diploclaws of each leg asymmetrically arranged with respect to the median plane of the leg (conventionally described as: 2121). The standard diploclaws of the Calohypsibius type have the primary and the secondary branches rigidly joined to one another with the suture clearly visible arising from the base of the claw; therefore the basal section of the claws is wide and stumpy, without a narrow stem ( Figs. 1 B, 7A,B). The two claws of each leg are similar in shape and size. The secondary branches may be more or less reduced ( Fig. 7 C) or absent (simple claws) ( Fig. 7 D). In some genera the hind legs may have only one claw or may be reduced and without claws.

Two types of bucco-pharyngeal apparatuses are recognizable within the family: the Hexapodibius type (Pilato 1969) and the Calohypsibius type (Pilato & Binda 1996).

The Hexapodibius type ( Fig. 8 A)

Buccal tube rigid and asymmetrical with respect to the frontal plane due to the presence of a ventral lamina; very narrow anterior portion of this lamina continues abruptly in a larger triangular portion with two processes pointing backwards and sideways. Peribuccal lamellae absent; six peribuccal papulae, sometimes forked, present with the sagittal plane passing between the papulae.

The Calohypsibius type ( Fig. 8 B–D)

Buccal tube rigid without ventral lamina; a dorsal and a ventral apophyses for the insertion of the stylet muscles, asymmetrical with respect to the frontal plane, are present on the anterior portion of the buccal tube; the dorsal apophysis is subdivided into two portions: the anterior portion is a stumpy hook with a blunt caudal apex; the caudal portion is a short longitudinal thickening. The ventral apophysis is a very slightly prominent ridge. Both of these apophyses have two processes, but those of the dorsal apophysis point backwards and sideways ( Fig. 8 C) while those of the ventral apophysis point laterally ( Fig. 8 D). Peribuccal lamellae absent; six peribuccal papulae present with the sagittal plane passing between the papulae.

Composition: Five genera are ascribed to the family: Calohypsibius , Haplohexapodibius , Haplomacrobiotus , Hexapodibius and Parhexapodibius .

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 7. Claws of Calohypsibiidae. A, claws normally developed; B, claws reduced of Hexapodibius; C, claws with reduced secondary branch; D, simple claws (the secondary branch is lacking). ap = accessory points; bs = basal section; pb = primary branch; sb = secondary branch. (A, from Binda & Pilato, 1969; B, from Pilato, 1969 a; C, from Pilato, 1973 a).

FIGURE 8. Bucco-pharyngeal apparatuses of: A, Hexapodibius type; B – D, Calohypsibius type: B, in lateral view; C, in dorsal view; D, in ventral view. cp = caudal processes; da = dorsal apophysis; dlt = dorsal longitudinal thickening; va = ventral apophysis; vl = ventral lamina.