Macrobiotoidea from Marley et al. 2011: “Parachela; claw pairs symmetrical (2112); AISM generally asymmetrical, due to the ventral lamina, with lateral caudal processes of crests and hooks.”
Macrobiotoidea from Bertolani et al. 2014: “Double claws symmetrical with respect to the median plane of the leg (sequence 2112); double claw of each leg similar in shape and size; each double claw characterized by the presence of a peculiar stalk (peduncle) with cylindrical or laminar shape; 10 peribuccal lamellae or papulae; buccal tube strengthened by a ventral lamina. Eggs laid freely and always surrounded by an ornamented shell.”
Macrobiotidae from Thulin 1928: “Fam. Macrobiotidae zeichnet sich dadurch aus, dass Sinnesanhänge am Kopfe fehlen. Die Krallen sind zweihakig. Die hintere an jeder Extremität kann mehr oder weniger vollständig in Basal- und Terminal-kralle aufgeteilt sein, die vordere ist dagegen niemals in dieser Weise differenziert. Die Länge und Weite der Mundröhre variiert erheblich innerhalb dieser Familie, ebenso die Form des Schlundkopfes. Die Mundöffnung ist nicht durch Klappen verschliessbar, aber bisweilen (bei vielen Macrobiotus-Arten) von einem Lamellenkranz umgeben. Die Stilette sind mehr oder weniger stark bogenförmig gekrümmt, mit der Konvexität des Bogens medialwärts gewendet, und kräftiger als bei den übrigen Tardigraden.”
Translation: Fam. Macrobiotidae is characterized by the fact that sensory appendages are missing on the head. The claws are double-hooked. The posterior of each claw may be more or less completely divided into basal and terminal [secondary] claws, whereas the anterior [primary branch] is never differentiated in this way. The length and width of the mouth tube varies considerably within this family, as does the shape of the pharynx. The mouth opening is not closed by flaps, but sometimes (in many Macrobiotus species) surrounded by a lamellae. The stylets are more or less curved, with the convexity of the arch turned towards the medial direction, and stronger than in other tardigrades.
Macrobiotidae from Guidetti et al. 2005: “Parachela with double-claws of each leg similar in shape and size and symmetrical with respect to the median plane of the leg (sequence 2112). Y-shaped claws, with claw branches fused over a tract of variable length (common tract). Ten peribuccal structures (lamellae or papulae) present. Epicuticular layer compact and uniform, without pillar-like structures.”
Macrobiotidae from Bertolani et al. 2014: “Double claws Y-shaped, with the two branches forming an evident common basal tract of variable length. Buccal tube completely rigid, or caudally annulated.”
Genus description from Schultze 1834: “Corpus elongatum, depresso-cylindricum, in decem segmenta distinctum. Pedes octo, alternis segmentis a quarto ad decimum affixi. Caput antennis destitutum, oculi duo.”
Translated: The body is an elongated, flattened cylinder in ten segments. Eight feet on alternate segments from the fourth to the tenth. No antennae on head, two eyes.
Genus description from Schuster et al. 1980: “Ten buccal lamellae present; without peribuccal papulae. Buccal tube short, rigid, without spiraled thickenings. Buccal mucrones and interior buccal baffles present. Pharynx contains apophyses, macroplacoids, or macro- and microplacoids, but no septulum. Cuticle with pores of various sizes, number, and distribution. Two double claws of each leg of similar size and shape; lunulae present; claws not connected; sequence 2,1,1,2. Eggs with protruding processes are laid freely.”
Genus description from Pilato & Binda 2010: “Claws of the hufelandi type. Bucco-pharyngeal apparatus of the Macrobiotus type, Macrobiotus variant. Pharyngeal apophyses and placoids present. Stylet furcae typically shaped. Lunules present in the known species. Eggs laid freely in the known species; egg shell with processes (only two exceptions are known).”
Citations:
Bertolani R, Guidetti R, Marchioro T, Altiero T, Rebecchi L, Cesari M. 2014. Phylogeny of Eutardigrada: New molecular data and their morphological support lead to the identification of new evolutionary lineages. Molecular Phylogenetics and Evolution. 76: 110-126.
Guidetti R, Gandolfi A, Rossi V, Bertolani R. 2005. Phylogenetic analysis of Macrobiotidae (Eutardigrada, Parachela): a combined morphological and molecular approach. Zoologica Scripta. 34 (3): 235-244.
Marley NJ, McInnes SJ, Sands CJ. 2011. Phylum Tardigrada: A re-evaluation of the Parachela. Zootaxa. 2819: 51-64.
Pilato G, Binda MG. 2010. Definition of families, subfamilies, genera, and subgenera of the Eutardigrada, and keys to their identification. Zootaxa. 2404: 1-54.
Schultze CAS. 1834. Macrobiotus hufelandii, animal e crustaceorum classe novum, reviviscendi post diuturnam asphyxiam et ariditatem potens. Berolini, Berlin.
Schuster RO, Nelson DR, Grigarick AA, Christenberry D. 1980. Systematic criteria of the Eutardigrada. Transactions of the American Microscopical Society. 99: 284-303.
Thulin G. 1928. Über die phylogenie und das system der tardigraden. Zoologisches Institut, Lund.
