TARDIGRADE KEY

Tag: Family Itaquasconidae

Raribius

Genus description from Gąsiorek & Michalczyk 2020: “S-shaped stylet supports. Pharynx spherical, sometimes short and thin bar-like placoids present. Claws miniaturised, with external primary branches not markedly longer than secondary ones.” Species key: Gąsiorek P, Blagden B, Morek W, Michalczyk Ł. 2024. What is a ‘strong’synapomorphy? Redescriptions of Murray’s type species and descriptions of new […]

Insulobius

Genus description from Gąsiorek & Michalczyk 2020: “AISM reduced, in the shape of thin and flat ridges. Buccal tube followed by a flexible annulated pharyngeal tube, without the drop-like apodeme between them; the pharyngeal annulation type unknown. Pharyngeal tube annulation does not extend towards the more proximal portions of the buccal tube. Stylet supports and […]

Guidettion

Genus description from Gąsiorek & Michalczyk 2020: “Peribuccal structures absent. AISM in the shape of semilunar hooks. Buccal tube followed by a flexible annulated pharyngeal tube, without the drop-like apodeme between them; the pharyngeal annulation is simple (composed of single annuli). An ovoid pharynx with three bar-like, short or elongated or granular macroplacoids. Claws of […]

Arctodiphascon

Genus description from Tumanov & Tsvetkova 2023: “Peribuccal structures consisted of six peribuccal lobes. AISM in shape of “semilu­nar hooks” asymmetrical with respect to fron­tal plane with dorsal apophyses being distinctlyhigher, shorter and thicker than ventral ones, caudal processes of both apophyses pointing posteriorly and laterally. Buccal tube followed by a flexible annulated pharyngeal tube, […]

Itaquasconidae

Formerly Itaquasconinae from Pilato 1969: “Unghie di tipo Hypsibius; apparato boccale di tipo Diphascon; placoidi presenti o assenti.” Translated: Claws of Hypsibius type; buccal apparatus of Diphascon type; placoids present or absent. Formerly Itaquasconinae from Bertolani et al. 2014: “Buccal tube followed by a flexible portion, without cuticular thickening between them; the flexible portion is an annulated pharyngeal tube in all genera (Parascon excluded); […]

Adropion

Genus description from Pilato 1987: “The ‘drop-like’ thickening is absent; the pharyngeal apophyses are sometimes well developed, generally small or lacking; the pharyngeal bulb and placoids are almost always long or very long.” Genus description from Bertolani et al. 2014: “Evident placoids and stylet supports.” N.B.: Diphascon (Diphascon) higginsi has small, flat drop, difficult to […]

Platicrista

Genus description from Pilato 1987: “The bucco-pharyngeal apparatus is of the Diphascon model with the apophyses for the insertion of the muscles of the stylets in the shape of ‘very wide and flat ridges’; they are symmetrical with respect to the frontal plane; and with the caudal processes poorly developed and pointing sideways; the furcae have the […]

Bindius

Genus description from Pilato 2009: “Claws of Hypsibius type. The bucco-pharyngeal apparatus […] is a variant of the Diphascon model (Pilato & Binda, 1983): the bucco-pharyngeal tube is subdivided into a rigid buccal tube and a flexible pharyngeal tube with a spiral thickening; buccal tube without ventral lamina. The dorsal and ventral apophyses for the insertion of the stylet […]

Astatumen

Genus description from Pilato 1997: “Claws of the Hypsibius-type; bucco-pharyngeal tube subdivided into an anterior, rigid portion (buccal tube) and a posterior, flexible portion (pharyngeal tube) provided with a spiral thickening. Stylet supports absent. Buccal tube, without ventral lamina, very short (only as long as the apophyses for the insertion of the muscles of the stylets). […]

Itaquascon

Genus description from Pilato 1997: “Claws of the Hypsibius-type; bucco-pharyngeal tube subdivided into an anterior, rigid portion (buccal tube) and a posterior, flexible portion (pharyngeal tube) provided with a spiral thickening. Stylet supports present. Buccal tube, without ventral lamina, clearly longer than the apophyses for the insertion of the muscles of the stylets. Apophyses for the […]

Claw Symmetry Relative To Median Plane Of Leg?

Image from Bingemer J, Hohberg K. 2017. An illustrated identification key to the eutardigrade species (Tardigrada, Eutardigrada) presently known from European soils. Soil Organisms. 89 (3): 127-149.

Stylet Support Insertion Point As Percentage Of Buccal Tube Length

Stylet support insertion point = ss divided by Buccal tube length, as %. Note anterior measurements begin at anterior margin of stylet sheaths, ss is centred where stylet supports reach buccal tube (this requires a good dorsal or lateral view for proper measurement)

Image from Tumanov DV. 2006. Five new species of the genus Milnesium (Tardigrada, Eutardigrada, Milnesiidae). Zootaxa. 1122: 1-23.

Buccal Tube Long, Mouth At Anterior Of A Protrusible Snout

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

Pharyngeal Tube With Spiral Reinforcement

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

Peribuccal papillae?

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

(Lateral) cephalic papillae, peribuccal papillae, Milnesiidae - type claws, exceptionally wide (and usually short) buccal tube?

Cephalic image modified from Nelson DR, Guidetti R, Rebecchi L. 2009. Tardigrada. Ch. 14 in Ecology and Classification of North American Freshwater Invertebrates, Thorp JH, Covich AP (eds.), 3rd ed.

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

Pharyngeal tube flexible?

Note: in a tardigrade with snout extended, the flex of the pharyngeal tube may not be obvious.

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

Serrated / dentate cuff / collar on legs IV

Left image from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

Right Image from Richters F. 1926. Tardigrada. in Krumbach T. 1927. Handbuch der Zoologie, 3rd band, Walter de Gruyter & Co.

Leg sensory structures

Typically papilla on leg IV (se4 in image) and variable shape on leg I

Image from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

Trunk appendages

Appendages (after Cirrus A) labeled according to plate … B (Scapular plate), C (First segmental plate), D (Second segmental plate), E (terminal plate). “B” is lateral, “Bd” is dorsal

Be careful! There can be great variability within a population, with individuals (especially juveniles) lacking some appendages. When in doubt, focus on other characters first!

Left image from Ramazzotti G, Maucci W. 1983. Il phylum Tardigrada(III edizione riveduta e aggiornata). English translation by C. W. Beasley, 1995. Memorie dell’ Istituto Italiano di Idrobiologia 41: 1-1012.

Right image cropped from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

Cirrus A form

Images modified from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

Lower image (Mopsechiniscus) modified from du Bois-Reymond Marcus E. 1944. Sobre tardigrados brasileiros. Communicaciones Zoologicas del Museo de Historia Natural de Montevideo. 1(13): 1-19 plus plates.

Terminal / caudal plate with two notches?

Images modified from Kristensen RM. 1987. Generic revision of the Echiniscidae (Heterotardigrada), with a discussion of the origin of the family. pp. 261-335 in Bertolani R (ed). Biology of Tardigrades: Selected symposia and monographs.

First image (Echiniscus) modified from Richters F. 1926. Tardigrada. in Krumbach T. 1927. Handbuch der Zoologie, 3rd band, Walter de Gruyter & Co.

Inner & outer buccal cirri present

Image modified from Nelson DR, Guidetti R, Rebecchi L. 2009. Tardigrada. Ch. 14 in Ecology and Classification of North American Freshwater Invertebrates, Thorp JH, Covich AP (eds.), 3rd ed.

Pseudosegmental plate between last medial plate & terminal plate?

Note on 2nd image, what you see before the terminal plate is either no plate, or a full-width medial plate; don’t confuse the latter with a pseudosegmental plate!
Also, sometimes the pseudosegmental plate is paired, like segmental plates II & III. It’s still pseudosegmental!

Images from Clifford HF. 1991. Aquatic invertebrates of Alberta. University of Alberta Press, Alberta, Canada.

Segmental plates larger than intersegmental?

Image modified from Lindahl & Balser (1999), http://www.iwu.edu/~tardisdp/Keypage35.html

Any Paired Plates?

Modified from Lindahl K, Balser S.  1999. Key to tardigrade genera [Internet]. Available from: https://sun.iwu.edu/~tardisdp/Keypage33.html