MICROHYPSIBIIDAE, Pilato, 1998

Gąsiorek, Piotr, Morek, Witold, Stec, Daniel, Blagden, Brian & Michalczyk, Łukasz, 2019, Revisiting Calohypsibiidae and Microhypsibiidae: Fractonotus Pilato, 1998 and its phylogenetic position within Isohypsibiidae (Eutardigrada: Parachela), Zoosystema 41 (6), pp. 71-89 : 83-84

TAXONOMIC ACCOUNT

OF THE MICROHYPSIBIIDAE SENSU STRICTO

Superfamily HYPSIBIOIDEA Pilato, 1969 (emended by Bertolani et al. 2014a)

Family MICROHYPSIBIIDAE Pilato, 1998

EMENDED DIAGNOSIS. — Very small eutardigrades (typically below 150 μm in length) without elliptical organs on the head. Cuticle smooth. Claws minute and asymmetrical with respect to the sequence of primary and secondary branches (2-1-2-1), with thin bases continuous with the primary branches. External and internal, and anterior and posterior claws different in shape but similar in size. Pseudolunulae absent. Accessory points symmetrical ( Fig. 11G ). Peribuccal papulae not visible under PCM. AISM asymmetrical with respect to the frontal plane, with the dorsal apophysis subdivided in two portions of different shapes ( Fig. 9A ). Stylet furcae of the Hypsibius - type. Pharyngeal apophyses similar in size to macroplacoids. Smooth eggs laid in exuviae.

COMPOSITION. — A monotypic family, comprising the genus Microhypsibius .

Figures

FIG. 11. — Comparison of Fractonotus-type (A-D, F), Calohypsibius-type (E), Microhypsibius-type (G), and Isohypsibius-type (H, I) claws (all but Fig. 11F PCM): Fractonotus verrucosus (Richters, 1900) n. comb.: A, claws I, arrowhead indicates weakly developed pseudolunula; B, claws II, interrupted line designates isohypsibioid claw curvature; C, claws IV, arrowhead indicates weakly developed pseudolunula; Fractonotus gilvus (Biserov, 1986) n. comb.; D, claws III, arrowhead indicates weakly developed pseudolunula; Calohypsibius ornatus (Richters, 1900); E, claws IV; Fractonotus caelatus (Marcus, 1928); F, claws IV; Microhypsibius truncatus Thulin, 1928; G, claws III (DIC); Isohypsibius prosostomus (Thulin, 1928); H, claws II; Isohypsibius coulsoni Kaczmarek, Zawierucha, Smykla & Michalczyk, 2012; I, claws II. Scale bars: 10 μm.

FIG. 9. — Schematic comparison of the AISM (lateral view) in: A, Fractonotus Pilato, 1998; B, Calohypsibius Thulin, 1928; C, Isohypsibius Thulin, 1928.