Mixibius

Superfamily: Hypsibioidea

Genus description from Pilato 1992: “Hypsibiidae, organi ellittici sul cap assenti; unghie esterne di tipo Isohypsibius ed interne dello stesso tipo ma un po’modificate in quanto l’angolo fra unghia basale e ramo secondario è un po’maggiore di 90°; apparato bucco-faringeo con tubo boccale rigido, privo di sbarretta di rinforzo ventrale e con una lieve asimmetria rispetto al piano frontale in quanto le apofisi ventrale e dorsale per l’inserzione dei muscoli degli stiletti, che sono ad uncino, risultano lievemente diverse l’una dal l’altra: quella ventrale ha l’estremità caudale appuntita, quella dorsale, più massiccia, ha l’estremità caudale smussata ed ingrossata. Mancano lamelle periboccali; bulbo faringeo con apofisi e placoidi.”

Translated: Hypsibiidae, elliptic organs on the head absent; external claws of the Isohypsibius type and internal of the same type but slightly modified since the angle between the basal claw and the secondary branch is slightly greater than 90°; bucco-pharyngeal apparatus with a rigid buccal tube, without a ventral reinforcement bar and with a slight asymmetry with respect to the frontal plane as the ventral and dorsal apophyses for the insertion of the muscles of the stylets, which are hooked, are slightly different one from the other: the ventral one has a pointed caudal end, the dorsal one, more massive, has the caudal extremity blunted and enlarged. Peribuccal lamellae are missing; pharyngeal bulb with apophyses and placoids.

Pilato G, Binda MG. 2010. Definition of families, subfamilies, genera, and subgenera of the Eutardigrada, and keys to their identification. Zootaxa. 2404: 1-54.

Citations:

Pilato G. 1992. Mixibius, nuovo genere di Hypsibiidae (Eutardigrada). Animalia. 19 (1/3): 121-125.

Claw type

tenuis: With stalk, a long common tract formed by the joined primary & secondary branches, and distal sections of both the secondary branch – shorter than the primary – and primary branch forming almost a right angle.
Insuetifurca: Modified hufelandi: Basal section subdivided into a very short stem & a large distal portion.
hufelandi: Primary & secondary branches rigidly joined, forming an acute angle, with variable but long common basal tract and cylindrical stalk.
Dactylobiotus: Basal section a trapezoidal lamina; secondary branch clearly shorter than primary and inserted near the base of the latter; the two branches form an almost right angle.
Mesobiotus: Primary & secondary branches rigidly joined, forming acute angle, with variable but long common basal tract with internal septum defining a distal part, with cylindrical stalk. Often very prominent, strong accessory point on primary.
Murrayon: Basal section a trapezoidal lamina; primary & secondary branches joined to each other for a very short portion and form an acute angle.
Xerobiotus: Whole double claw equally sclerified; basal section not subdivided into a basal stem & distinct distal portion; no separating septa present; primary & secondary branches rigidly joined forming an acute angle.
Hypsibius: Secondary branch forming a continuous curve with its basal tract; in external claws the primary branch connected to the basal tract with a flexible part while the inner claw is rigid.
Ramazzottius: External claws with basal section longer than the secondary branch; primary branch very long and slender and connected to basal tract with an evident, thin, flexible tract; internal claws short & stout, rigid.
Ramajendas: External claws similar to Hypsibius type with extremely long and slender primary branch; internal claw similar to Isohypsibius type.
Microhypsibius: Small, rigid, with an evident thin basal tract continuous with the primary branch; secondary branch rigidly joined to the primary branch at a distance from the base of the claw.
Calohypsibius: Small, rigid, in frontal view with a base as large as the sum of the primary and secondary branch widths, without a suture between the two branches.
Hexapodibius: Very short, without common basal tract, with base as large as the sum of the primary and secondary branches.
Isohypsibius: Secondary branch inserted perpendicularly on the claw basal tract.
Eremobiotus: Isohypsibius-type very modified with two branches of each claw joined to one another for a long portion of their length constituting a large common tract from which the two distal tracts diverge forming an angle of almost 180°.
Bertolanius: Subdivided into three distinct sections: basal section, secondary branch and primary branch (rigidly joined to the secondary branch), one on top of the other and separated by septa; the angles between the main and secondary branch different in external and internal claws – and acute angle (about 45°) is formed by the external claw, and an almost right angle (about 80°) by the internal claw; internal claws can rotate on their base up to 180°.
Vladimirobius: external at least 2x length of internal (measured from base of claw), internal very wide at the junction of primary and secondary branches, short and thin basal part, primary branches with very prominent gibbosity-like projection near the junction of primary and secondary branches; external very thin with long basal part; accessory points of both claws very near to end of primary branch.
Calcarobiotus: Basal section, with or without basal spurs, subdivided into a thin flexible stem & a wide distal section in the shape of an upside-down triangle distally delmited by a septum; primary & secondary branches similar in shape & size.
Macroversum: Basal section subdivided into a thin, flexible, stem and distal portion not very sclerotized; primary & secondary branches connected to each other for a short portion and form an almost right angle.