TARDIGRADE KEY

Tag: Family Echiniscidae

Zealandiscus

Genus description from Kaczmarek & Roszkowska 2021: Echiniscidae with only cephalic cirri present. External and internal cirri very long.On dorsal side head plate, scapular plate, two pairs of segmental (paired) plates (s1 and s2), three median plates (m1, m2 and m3) and terminal plate present. Pseudosegmental plate absent. Incisions (notches) on terminal plate present. On […]

Viridiscus

Genus description from Gąsiorek et al. 2019: “Small to large echiniscids with red granulate eyes. Body colour green, through brown, to almost black. Only cephalic cirri present. Two pairs of segmental plates and two median plates. Incisions (notches) on caudal plate. Pseudosegmental and ventral plates absent. Dorsal plate sculpture composed of intracuticular sponge layer and […]

Stellariscus

Genus description from Gąsiorek et al. 2018: “Small echiniscids with black eyes. Very long, rigid buccal tube lacking stylet supports. Only cephalic cirri present. Two pairs of segmental plates, unpaired scapular + caudal plates, and three median plates on the dorsum. Incisions (notches) on the caudal plate. No pseudosegmental plates. Sculpture composed of large intra-cuticular […]

Nebularmis

Genus description from Gąsiorek et al. 2019: “Small to medium-sized echiniscids with red granulate eyes. Long, rigid and thick buccal tube lacking stylet supports. Cirrophores of the cephalic cirri weakly outlined. Only cephalic cirri present. Two pairs of segmental plates and two median plates. Incisions (notches) on caudal plate. Pseudosegmental plates absent. Ventral plates present, […]

Kristenseniscus

Genus description from Gąsiorek et al. 2019: “Small echiniscids with red granulate eyes. Only cephalic cirri present. Two pairs of segmental plates and two median plates. Scapular, paired segmental and caudal (terminal) plates subdivided into smaller subplates (autapomorphy). Sparsely scattered small pores on rims delimiting the subplates. Incisions (notches) on caudal plate. Pseudosegmental and ventral […]

Claxtonia

Genus description from Gąsiorek 2019: “Small echiniscids with red granulate eyes. Only cephalic cirri present. Cirri A longer than 30% of body length. Two pairs of segmental plates and two median plates. Incisions (notches) on caudal (terminal) plate. Pseudosegmental and ventral plates absent. Sculpture composed of regular granulation, i.e. circular or polygonal, dense round epicuticular […]

Barbaria

Genus description from Gąsiorek et al. 2019: “Small to medium-sized echiniscids with red granulate eyes. Only cephalic cirri present. Two pairs of segmental plates and two or three median plates. Incisions (notches) on caudal (terminal) plate. Pseudosegmental and ventral plates absent. Sculpture composed of “double granulation” on most dorsal plates, i.e. epicuticular pseudopores and/or pores […]

Echiniscidae

terrestrial species (found also in freshwater){Seminal receptacles absent. Dorsal plates present. Adult with 4 claws on each leg.}(Kristensen 1987) (Degma P, Guidetti R. 2018. Tardigrade Taxa. In: Water Bears: The biology of tardigrades. Schill RO, Editor. Switzerland: Springer Nature. p. 371-409. DOI: 10.1007/978-3-319-95702-9_15.)

Antechiniscus

Antechiniscus, from Kristensen 1987: Echiniscidae with black eyes, unflexible buccal tube. Unpaired pseudosegmental plates (II’ and III’) present posterior to paired segmental plates II and III. Anterior to the caudal plate (IV) is a small bar-shaped pseudosegmental plate (IV’) which is slightly overlapped by a large undivided median plate (m 3). colour grey to light […]

Pseudechiniscus

From Ramazzotti & Maucci: “After the second paired plate, or after the third median plate if present, follows a pseudosegmental plate, paired or unpaired, and then the terminal plate; buccal cirri present; cirri A of filament shape.” From Kristensen 1987: “Echiniscidae with black eyes: rigid buccal canal, stylet supports may be present, but very tiny […]

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