Isohypsibioidea from Marley et al. 2011: “Parachela. Claws asymmetrical (2121); Isohypsibius-type claw pairs; AISM ridged.”
Isohypsibioidea from Bertolani et al. 2014: “Double claws asymmetrical with respect to the median plane of the leg (2121), normally with similar shape and size on each leg; double claws of the Isohypsibius type (secondary branch of the external claw inserted perpendicularly on the claw basal tract), or reduced from it: Hexapodibius type (very short, without common basal tract, with a base as large as the sum of the primary and secondary branch widths, and with an evident suture between primary and secondary branch); Haplomacrobiotus type (one branch only); completely absent (Apodibius). Buccal tube completely rigid (apart Paradiphascon; see below) and often relatively large, without (Dastychius, Eremobiotus, Halobiotus, Isohypsibius, Paradiphascon, Pseudobiotus, Thulinius) or with (Apodibius, Doryphoribius, Haplomacrobiotus, Haplohexapodibius, Hexapodibius, Parhexapodibius) ventral lamina. Eggs with smooth shell laid within the exuvium.”
Isohypsibiidae from Marley et al. 2011: “Isohypsibioidea. Claw pairs of similar size and shape. External and internal claws exhibiting articulation (the basal section and secondary branch form a solid unit while the primary branch and secondary branch articulate). Claws Isohypsibius-type, forming a right-angle between basal section and secondary branch. AISM ridge-like.”
Genus description from Pilato 2013: “Claws of the Isohypsibius type; double claws of the same leg slightly different in shape and size; rigid buccal tube without ventral lamina but with a dorsal and a ventral apophysis for the insertion of the stylet muscles in shape of long, continuous ridges tailing off caudally and almost reaching the level of the stylet supports; anterior portion of both apophyses with caudal processes pointing backwards and sideways. At about a quarter the length of the ridged apophyses is an incision and septum. Six peribuccal lobes present; peribuccal lamellae absent; structures in the form of peribuccal papulae present, but this should be confirmed. Stylet furcae typically shaped, i.e. the basal portion of the two caudal branches are enlarged with thickened, swollen, and rounded apices; pharyngeal bulb with apophyses and placoids. Lunules present in the monotypic species. Smooth eggs laid in the exuvium.”
Citations:
Bertolani R, Guidetti R, Marchioro T, Altiero T, Rebecchi L, Cesari M. 2014. Phyloeny of Eutardigrada: New molecular data and their morphological support lead to the identification of new evolutionary lineages. Molecular Phylogenetics and Evolution. 76: 110-126.
Marley NJ, McInnes SJ, Sands CJ. 2011. Phylum Tardigrada: A re-evaluation of the Parachela. Zootaxa. 2819: 51-64.
Pilato G. 2013. The taxonomic value of the structures for the insertion of the stylet muscles in the Eutardigrada, and description of a new genus. Zootaxa. 3721 (4): 365-378.
