TARDIGRADE KEY

Murrayon

Biserov, B. I. (1988) Пресноводные Тихоходки Некоторых Районов СССР. Зоологический Журнал, 67(12): 1798-1811.

Class: Eutardigrada

Order: Parachela

Superfamily: Macrobiotoidea

Family: Murrayidae

Click taxa for descriptions

Genus description from Bertolani & Pilato 1988: Macrobiotidae con unghie di tipo pullari, ossia con la porzione basale a laminetta trapezoidale e i due rami divergenti fin dalla base (unghie a V) e formanti un angolo acuto; le basi delle due unghie di ciascuna zampa sono indipendenti, ossia non collegate fra loro da alcun ispessimento cuticolare. Nelle specie finora note sono presenti lunule. Tubo boccale rigido con sbarretta di rinforzo ventrale a margine inciso così da apparire provvista di un vistoso « uncino ». Lamelle periboccali presenti. Bulbo faringeo provvisto di apofisi e di placoidi. Nelle specie finora note le uova hanno guscio ornamentato.”

Translated with help of Google Translate: Macrobiotidae with pullari-type claws, i.e. with the basal portion in the form of a trapezoidal lamina and the two branches diverging from the base (V-shaped claws) and forming an acute angle; the bases of the two claws of each leg are independent, i.e. not connected to each other by any cuticular thickening. In the species known so far, lunulae are present. Rigid buccopharyngeal tube with ventral lamina with incised margin so as to appear to have a conspicuous “hook”. Peri-oral lamellae present. Pharyngeal bulb provided with apophyses and placoids. In the species known so far, the eggs have an ornamented shell.

Genus description from Guidetti et al. 2022: “Claws of Murrayon type (=pullari type): basal section of the double claw appears as a trapezoidal lamina (in lateral view); primary and secondary branches similar in length and joined to each other for a very short portion, forming an acute angle (V-shaped); lunules present. Two macroplacoids in the pharynx. Epicuticular pillar-like structure not visible with light microscopy.”

Species key: Guidetti R, Giovannini I, Del Papa V, Ekrem T, Nelson DR, Rebecchi L, Cesari M. 2022. Phylogeny of the asexual lineage Murrayidae (Macrobiotoidea, Eutardigrada) with the description of Paramurrayon gen. nov. and Paramurrayon meieri sp. nov. Invertebrate Systematics. 36(12): 1099-1117.

Bertolani, R. & Pilato, G. (1988) Struttura delle unghie nei Macrobiotidae e descrizione di Murrayon n. gen. (Eutardigrada). Animalia. 15, 17-24.
Bertolani, R. & Pilato, G. (1988) Struttura delle unghie nei Macrobiotidae e descrizione di Murrayon n. gen. (Eutardigrada). Animalia. 15, 17-24.

Citations:

Bertolani, R. & Pilato, G. (1988) Struttura delle unghie nei Macrobiotidae e descrizione di Murrayon n. gen. (Eutardigrada). Animalia. 15, 17-24.

Guidetti, R., Giovannini, I., Del Papa, V., Ekrem, T., Nelson, D.R., Rebecchi, L. & Cesari, M. (2022) Phylogeny of the asexual lineage Murrayidae (Macrobiotoidea, Eutardigrada) with the description of Paramurrayon gen. nov. and Paramurrayon meieri sp. nov. Invertebrate Systematics, 36(12), 1099–1117.

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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