Skip to main content Skip to main navigation menu Skip to site footer
Responsive image
Issue: Vol. 4294 No. 1: 17 Jul. 2017
Type: Article
Published: 2017-07-17
DOI: 10.11646/zootaxa.4294.1.1
Page range: 1–45
Abstract views: 550
PDF downloaded: 20

A dichotomous key to the genera of the Marine Heterotardigrades (Tardigrada)

Department of Biology, Faculty of Sciences, University of Porto, Rua Campo Alegre s/n, FC4, 4169-007 Porto, Portugal. MARE, Marine and Environmental Science Centre, ISPA – Instituto Universitário, Rua Jardim do Tabaco 34, 1149-041 Lisboa, Portugal.
Department of Biology, Warren Wilson College, PO Box 9000, Asheville, NC 28815, USA.
Department of Biology, University of Copenhagen, Universitetsparken 13, DK-2100 Copenhagen , Denmark.
Section of Biosystematics, Natural History Museum of Denmark, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen Ø, Denmark.
Section of Biosystematics, Natural History Museum of Denmark, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen Ø, Denmark.
Tardigrada Arthrotardigrada marine Echiniscoidea tardigrades taxonomy water bears

Abstract

This is an identification guide to the 47 currently described genera of marine heterotardigrades. We provide clear definitions and illustrations of relevant anatomy and an easy to use dichotomous key. The aim of the present contribution is to enable more people to identify collected specimens of marine heterotardigrades, and hopefully, encourage more people to study this intriguing group of animals. The paper is divided into three parts. The first part gives a brief introduction to heterotardigrade morphology with special emphasis on taxonomically important characters. The second part is the actual key, which is accompanied by illustrations of both habitus and detailed foot morphology of the marine heterotardigrade genera. The third part provides up to date diagnoses of the orders, families, subfamilies and genera of marine heterotardigrades according to the most recent emendments. With the generic diagnoses, we provide a bibliography with selected literature that relates to each specific genus.

 

 

References

  1. Bartels, P.J., Fontoura, P. & Nelson, D.R. (2015) New records of marine tardigrades from Moorea, French Polynesia, with the description of Styraconyx turbinarium sp. nov. (Arthrotardigrada, Halechiniscidae). Zootaxa, 3955 (3), 389–402.
    https://doi.org/10.11646/zootaxa.3955.3.6

    Bartels, P.J., Apodaca, J.J., Mora, C. & Nelson, D.R. (2016) A global biodiversity estimate of a poorly known taxon: Phylum Tardigrada. Zoological Journal of the Linnean Society, 178 (4), 730–736.
    https://doi.org/10.1111/zoj.12441

    Beasley, C.W. (1995) The phylum Tardigrada. Published by the translator Clark Beasley, Abilene, 1014 pp. [3rd Edition by G. Ramazzotti and W. Maucci, English Translation]

    Bello, G. & Grimaldi de Zio, S. (1998) Phylogeny of the genera of the Stygarctidae and related families (Tardigrada: Heterotardigrada). Zoologischer Anzeiger, 237, 171–183.

    Bertolani, R., Altiero, T. & Nelson, D.R. (2009) Tardigrada (Water Bears). In: Likens, G.E. (Ed.), Encyclopedia of Inland Waters, 2, pp. 443–455.
    https://doi.org/10.1016/B978-012370626-3.00188-5

    Binda, M.G. (1978) Risistemazione di alcuni tardigradi con l’istituzione di un nuovo genere di Oreellidae e della nuova famiglia Archechiniscidae. Animalia, 5, 307–314.

    Boesgaard, T.M. & Kristensen, R.M. (2001) Tardigrades from Australian marine caves. With a redescription of Actinarctus neretinus (Arthrotardigrada). Zoologischer Anzeiger, 240, 253–264.
    https://doi.org/10.1078/0044-5231-00033

    Borner, J., Rehm, P., Schill, R.O., Ebersberger, I. & Burmester, T. (2014) A transcriptome approach to ecdysozoan phylogeny. Molecular Phylogenetics and Evolution, 80, 79–87.
    https://doi.org/10.1016/j.ympev.2014.08.001

    Bussau, C. (1992) New deep-sea Tardigrada (Arthrotardigrada, Halechiniscidae) from a manganese nodule area of the eastern South Pacific. Zoologica Scripta, 21 (1), 79–91.
    https://doi.org/10.1111/j.1463-6409.1992.tb00311.x

    Cantacuzène, M.A. (1951) Tardigrade marin nouveau, commensal de Limnoria lignorum (Rathke). Compte Rendu de l’Académie des Sciences, 232, 1699–1700.

    Chang, C.Y. & Rho, H.S. (1997) Two new marine tardigrades from Palawan Island, the Philippines. The Korean Journal of Biological Sciences, 1, 419–423.

    Chang, C.Y. & Rho, H.S. (1998a) Three new tardigrade species associated with barnacles from the Thai coast of Andaman Sea. The Korean Journal of Biological Sciences, 2, 323–331.
    https://doi.org/10.1080/12265071.1998.9647426

    Chang, C.Y. & Rho, H.S. (1998b) Two marine tardigrade species of genus Anisonyches (Heterotardigrada: Echiniscoididae) from Mindanao, the Philippines. The Korean Journal of Systematic Zoology, 14 (2), 91–98.

    Chang, C.Y. & Rho, H.S. (2002) Taxonomic study of marine tardigrades from Korea. II Genus Halechiniscus (Heterotardigrada, Arthrotardigrada, Halechiniscidae). The Korean Journal of Systematic Zoology, 18 (1), 91–98.

    Cuénot, L. (1892) Commensaux et parasites des Echinodermes (21ème note). Revue de Biologie, Nord de la France, 5, 1–22.

    D’Addabbo Gallo, M., Grimaldi de Zio, S. & Morone De Lucia, M.R. (1984) Styraconyx testudo n. sp., a new Styraconyxinae of the Mediterranean Sea (Arthrotardigrada: Halechiniscidae). Oebalia, 10, 95–103.

    D’Addabbo Gallo, M., Grimaldi de Zio, S. & Morone De Lucia, M.R. (1986) Description of two species of Halechiniscidae belonging to the sub-families Halechiniscinae and Styraconyxinae (Tardigrada: Heterotardigrada). Oebalia, 13, 69–75.

    D’Addabbo Gallo, M., Morone De Lucia, M.R. & Grimaldi de Zio, S. (1989) Two new species of the genus Styraconyx (Tardigrada: Heterotardigrada). Cahiers de Biologie Marine, 30, 17–33.

    D’Addabbo Gallo, M., Grimaldi de Zio, S., Morone De Lucia, M.R. & Troccoli, A. (1992) Halechiniscidae and Echiniscoididae from Western Mediterranean Sea. (Tardigrada: Heterotardigrada). Cahiers de Biologie Marine, 33, 299–318.

    Degma, P. & Guidetti, R. (2007) Notes to the current checklist of Tardigrada. Zootaxa, 1579, 41–53.

    Degma, P., Bertolani, R. & Guidetti, R. (2009-2016) Actual checklist of Tardigrada species. 2009–2016, 31st Edition: 15 December 2016, pp. 46. Available from: http://www.tardigrada.modena.unimo.it/miscellanea/Actual%20checklist%20of%20Tardigrada.pdf (accessed 28 March 2017)

    Delamare-Deboutteville, C. & Renaud-Mornant, J. (1965) Un remarquable genre de Tardigrades des sables coralliens de Nouvelle-Calédonie. Compte Rendu de l’Académie des Sciences de Paris, 266, 2581–2583.

    de Zio Grimaldi, S., Gallo D`Addabbo, M. & De Lucia Morone, M.R. (1992) Neoarctus primigenius n. g., n. sp., a new Stygarctidae of the Tyrrhenian Sea (Tardigrada, Arthrotardigrada). Bollettino di Zoologia, 59, 309–313.
    https://doi.org/10.1080/11250009209386687

    de Zio Grimaldi, S., Gallo D`Addabbo , M. & De Lucia Morone, M.R. & Troccoli, A. (1995/1996) Hemitanarctus chimaera n.g., n.sp., new Halechiniscidae from the Ionian Sea (Tardigrada, Heterotardigrada). Zoologischer Anzeiger, 234, 167–174.

    de Zio Grimaldi, S., Gallo D’Addabbo, M. & De Lucia Morone, M.R. (1998) A new Stygarctidae from South Tyrrhenian Sea (Tardigrada, Heterotardigrada). Cahiers de Biologie Marine, 39, 85–91.

    de Zio Grimaldi, S., Lamarca, A., Gallo D`Addabbo, M. & Pietanza, R. (1999) Florarctinae of Asdhu Island, Maldives, Indian Ocean (Tardigrada, Heterotardigrada). Italian Journal of Zoology, 66, 383–391.
    https://doi.org/10.1080/11250009909356282

    Dewel, R.A., Nelson, D.R. & Dewel, W.C. (1993) Tardigrada. In: Harrison, F.W. & Rice, M.E. (Eds.), Microscopic Anatomy of Invertebrates. Vol. 12. Onychophora, Chilopoda and Lesser Protostomata. Wiley-Liss, New York, pp. 143–183.

    du Bois-Reymond Marcus, E. (1952) On South American Malacopoda. Boletim da Faculdade de Filosofia, Ciências e Letras da Universidade de São Paulo, serie Zoologia, 17, 189–209.

    Dunn, C.W., Hejnol, A., Matus, D.Q., Pang, K., Browne, W.E., Smith, S.A., Seaver, E., Rouse, G.W., Obst, M., Edgecombe, G.D., Sørensen, M.V., Haddock, S.H.D., Schmidt-Rhaesa, A., Okusu, A., Kristensen, R.M., Wheeler, W.C., Martindale, M.Q. & Giribet, G. (2008) Broad phylogenomic sampling improves resolution of the animal tree of life. Nature, 452, 745–750.
    https://doi.org/10.1038/nature06614

    Dunn, C.W., Giribet, G., Edgecombe, G.D. & Hejnol, A. (2014) Animal phylogeny and its evolutionary implications. Annual Review of Ecology Evolution and Systematics, 45, 371–395.
    https://doi.org/10.1146/annurev-ecolsys-120213-091627

    Fujimoto, S. (2014) A new Stygarctus (Arthrotardigrada: Stygarctidae) from Japan, with entangled seminal receptacle ducts. Zootaxa, 3784 (2), 187–195.
    https://doi.org/10.11646/zootaxa.3784.2.8

    Fujimoto, S. (2015a) Halechiniscidae (Heterotardigrada, Arthrotardigrada) of Oura Bay, Okinawajima, Ryukyu Islands, with descriptions of three new species. Zookeys, 483, 149–166.
    https://doi.org/10.3897/zookeys.483.8936

    Fujimoto, S. (2015b) Quisarctus yasumurai gen. et sp. nov. (Arthrotardigrada: Halechiniscidae) from a submarine cave, off Iejima, Ryukyu Islands, Japan. Zootaxa, 3948 (1), 145–150.
    https://doi.org/10.11646/zootaxa.3948.1.10

    Fujimoto, S. & Miyazaki, K. (2013) Neostygarctus lovedeluxe n. sp. from the Miyako Islands, Japan: The first record of Neostygarctidae (Heterotardigrada: Arthrotardigrada) from the Pacific. Zoological Science, 30, 414–419.
    https://doi.org/10.2108/zsj.30.414

    Fujimoto, S. & Yamasaki, H. (2017) A new genus and species of Renaudarctidae (Heterotardigrada: Arthrotardigrada) from Ryukyu Archipelago, Japan, Marine Biology Research, 1–2. [published online]
    https://doi.org/10.1080/17451000.2016.1257809

    Fujimoto, S., Miyazaki, K. & Suzuki, A.C. (2013) A new marine tardigrade, Tanarctus diplocerus (Arthrotardigrada: Halechiniscidae) from Japan. Journal of the Marine Biological Association of the United Kingdom, 93 (4), 955–961.
    https://doi.org/10.1017/S0025315412000689

    Fujimoto, S., Jørgensen, A. & Hansen, J.G. (2016) A molecular approach to arthrotardigrade phylogeny (Heterotardigrada, Tardigrada). Zoologica Scripta. [published online]
    https://doi.org/10.1111/zsc.12221

    Gallo d’Addabbo, M., de Zio Grimaldi, S., De Lucia Morone, M.R., Pietanza, R, D’Addabbo, R. & Todaro, M.A. (1999) Diversity and dynamics of an interstitial Tardigrada population in the Meloria Shoals, Ligurian Sea, with a redescription of Batillipes similis (Heterotardigrada, Batillipedidae). Italian Journal of Zoology, 66, 51–61.
    https://doi.org/10.1080/11250009909356237

    Gallo d’Addabbo, M., de Zio Grimaldi, S. & D’Addabbo, R. (2000) Pseudostygarctus apuliae (Tardigrada, Heterotardigrada): a new species from the lower Adriatic Sea. Italian Journal of Zoology, 67, 125–128.
    https://doi.org/10.1080/11250000009356302

    Gallo d’Addabbo, M., de Zio Grimaldi & Sandulli, R. (2001) Heterotardigrada of two submarine caves in S. Domino Island (Tremiti Islands) in the Mediterranean Sea. Zoologischer Anzeiger, 240, 361–369.
    https://doi.org/10.1078/0044-5231-00043

    Gallo d’Addabbo, M., Sandulli, R. & de Zio Grimaldi, S. (2005) New Batillipedidae (Tardigrada, Heterotardigrada) from the Orosei Gulf, Sardinia, Tyrrhenian Sea. Zoologischer Anzeiger, 243, 219–225.
    https://doi.org/10.1016/j.jcz.2004.07.004

    Grimaldi de Zio, S. & D’Addabbo Gallo, M. (1975) Reproductive cycle of Batillipes pennaki Marcus (Heterotardigrada) and observations on the morphology of the female genital apparatus. Pubblicazioni della Stazione Zoologica di Napoli, 39 (Supplement), 212–225.

    Grimaldi de Zio, S. & D’Addabbo Gallo, M. (1987) Archechiniscus minutus n. sp. and its systematic position within Arthrotardigrada (Tardigrada: Heterotardigrada). In: Bertolani, R. (Ed.), Biology of Tardigrades, Selected Symposia and Monographs U.Z.I. Vol. 1, Muchi, Modena, pp. 253–260.

    Grimaldi de Zio, S., D’Addabbo Gallo, M. & Morone De Lucia, M.R. (1982a) Neostygarctus acanthophorus, n. gen., n. sp., nuovo tardigrado marino del mediterraneo. Cahiers de Biologie Marine, 23, 319–323.

    Grimaldi de Zio, S., D’Addabbo Gallo, M., Morone De Lucia, M.R., Vaccarella, R. & Grimaldi, P. (1982b) Quattro nuove specie di Halechiniscidae rinvenute in due grotte sottomarine dell’Italia meridionale. (Tardigrada: Heterotardigrada). Cahiers de Biologie Marine, 23, 415–426.

    Grimaldi de Zio, S., D’Addabbo Gallo, M. & Morone De Lucia, M.R. (1987a) Adaptive radiation and phylogenesis in marine Tardigrada and the establishment of Neostygarctidae, a new family of Heterotardigrada. Bollettino di Zoologia, 54, 27–33.
    https://doi.org/10.1080/11250008709355552

    Grimaldi de Zio, S., D'Addabbo Gallo, M., Morone De Lucia, M.R. & D’Addabbo, L. (1987b) Marine Arthrotardigrada and Echiniscoidea (Tardigrada, Heterotardigrada) from the Indian Ocean. Bollettino di Zoologia, 4, 347–357.
    https://doi.org/10.1080/11250008709355608

    Grimaldi de Zio, S., D’Addabbo Gallo, M. & Morone De Lucia, M.R. (1988) Two new Mediterranean species of the genus Halechiniscus (Tardigrada, Heterotardigrada). Bollettino di Zoologia, 3, 205–211.
    https://doi.org/10.1080/11250008809386618

    Grimaldi de Zio, S., D’Addabbo Gallo, M. & Morone De Lucia, M.R. (1990a) Revision of the genus Halechiniscus (Halechiniscidae, Arthrotardigrada). Cahiers de Biologie Marine, 31, 271–279.

    Grimaldi de Zio, S., D’Addabbo Gallo, M., Morone De Lucia, M.R. & Troccoli, A. (1990b) New description of Neostygarctus acanthophorus (Tardigrada, Arthrotardigrada). Cahiers de Biologie Marine, 31, 409–416.

    Gross, V., Miller, W.R. & Hochberg, R. (2014) A new tardigrade, Mutaparadoxipus duodigifinis gen. nov., sp. nov. (Heterotardigrada: Arthrotardigrada), from the southeastern United States. Zootaxa, 3835 (2), 263–272.
    https://doi.org/10.11646/zootaxa.3835.2.6

    Grothman, G.T., Johansson, C., Chilton, G., Kagoshima, H., Tsujimoto, M. & Suzuki, A.C. (2017) Gilbert Rahm and the Status of Mesotardigrada Rahm, 1937. Zoological Science, 34 (1), 5–10.
    https://doi.org/10.2108/zs160109

    Guidetti, R. & Bertolani, R. (2005) Tardigrade taxonomy: an updated check list of the taxa and a list of characters for their identification. Zootaxa, 845 (1), 1–46.
    https://doi.org/10.11646/zootaxa.845.1.1

    Hallas, T.E. & Kristensen, R.M. (1982) Two new species in the tidal genus Echiniscoides from Rhode Island, U.S.A. (Echiniscoididae Heterotardigrada). In: Nelson, D. (Ed.), Proceedings of the Third International Symposium on the Tardigrada. August 3–6, 1980, East Tennessee State University Press, Johnson City, TN, pp. 179–192.

    Hansen, J.G. (2005) The ongoing investigation of the Faroe Bank tardigrade fauna. Fróᵭskapparrit supplementum. Proceedings from the BIOFAR Symposium, Tórshavn, Faroe Islands, 24–26 April 2003, North-East Atlantic marine benthic organisms in the Faroes – taxonomy, distribution and ecology, 220–223.

    Hansen, J.G. (2007) The deep-sea elements of the Faroe Bank tardigrade fauna with a description of two new species. Journal of Limnology, 66 (Supplement 1), 12–20.
    https://doi.org/10.4081/jlimnol.2007.s1.12

    Hansen, J.G. & Kristensen, R.M. (2006) The “hyena female” of tardigrades and descriptions of two new species of Megastygarctides (Arthrotardigrada: Stygarctidae) from Saudi Arabia. Hydrobiologia, 558, 81–101.
    https://doi.org/10.1007/s10750-005-1409-5

    Hansen, J.G., Gallo D’Addabbo, M. & de Zio Grimaldi, S. (2003a) A comparison of morphological characters within the genus Rhomboarctus (Tardigrada: Heterotardigrada) with the description of two new species. Zoologischer Anzeiger, 242, 83–96.
    https://doi.org/10.1078/0044-5231-00089

    Hansen, J.G., Kristensen, R.M. & Arbizu, P.M. (2003b) Deep-sea tardigrades from the Angola Basin. Abstract in: First International DIVA Workshop, Wilhelmshaven, 5–6 June 2003, 23.

    Hansen, J.G., Kristensen R.M. & Jørgensen, A. (2012) The armoured marine tardigrades (Arthrotardigrada, Tardigrada). Scientia Danica, Series B. Biologica, 2, 1–91.

    Hansen, J.G., Kristensen, R.M., Jørgensen, A., Accogli, G, D’Addabbo, R. & Gallo, M. (2016) Postembryonic development, paedomorphosis, secondary sexual dimorphism and population structure of a new Florarctus species (Tardigrada, Heterotardigrada) Zoological Journal of the Linnean Society, 178, 871–877.
    https://doi.org/10.1111/zoj.12436

    Hay, W.P. (1917) A new species of bear-animalcule from the coast of North Carolina. Proceedings of The United States National Museum, 53, 251–254.
    https://doi.org/10.5479/si.00963801.53-2203.251

    Herapath, W.B. (1865) On the genus Synapta, with some new British species. Quarterly Journal of Microscopical Science, New Series, 5, 1–7.

    Jørgensen, A. & Kristensen, R.M. (2001) A new tanarctid arthrotardigrade with buoyant bodies. Zoologischer Anzeiger, 240, 425–439.
    https://doi.org/10.1078/0044-5231-00051

    Jørgensen, A., Faurby, S., Hansen, J.G., Møbjerg, N. & Kristensen, R.M. (2010) Molecular phylogeny of Arthrotardigrada. Molecular Phylogenetics and Evolution, 54, 1006–1015.
    https://doi.org/10.1016/j.ympev.2009.10.006

    Jørgensen, A., Boesgaard, T.M., Møbjerg, N. & Kristensen, R.M. (2014) The tardigrade fauna of Australian marine caves: With descriptions of nine new species of Arthrotardigrada. Zootaxa, 3802 (4), 401–443.
    https://doi.org/10.11646/zootaxa.3802.4.1

    Kaczmarek, Ł., Bartels, P.J., Roszkowska, M. & Nelson, D.R. (2015) The zoogeography of marine tardigrades. Zootaxa, 4037 (1), 1–189.
    https://doi.org/10.11646/zootaxa.4037.1.1

    Kinchin, I.M. (1994) The Biology of Tardigrades. Portland Press, London, 186 pp.

    Kristensen, R.M. (1978) Notes on marine heterotardigrades. 1. Description of two new Batillipes species, using the electron microscope. Zoologischer Anzeiger, 200, 1–17.

    Kristensen, R.M. (1980) Zur Biologie des marinen Heterotardigraden Tetrakentron synaptae. Helgoländer Meeresuntersuchungen, 34, 165–177.
    https://doi.org/10.1007/BF01984038

    Kristensen, R.M. (1981) Sense organs of two marine arthrotardigrades (Heterotardigrada, Tardigrada). Acta Zoologica (Stockholm), 62 (1), 27–41.
    https://doi.org/10.1111/j.1463-6395.1981.tb00614.x

    Kristensen, R.M. (1982) The first record of cyclomorphosis in Tardigrada based on a new genus and species from Arctic meiobenthos. Zeitschrift für Zoologische Systematik und Evolutionsforschung, 20 (4), 249–270.
    https://doi.org/10.1111/j.1439-0469.1983.tb00552.x

    Kristensen, R.M. (1984) On the biology of Wingstrandarctus corallinus nov. gen. et spec., with notes on the symbiontic bacteria in the subfamily Florarctinae (Arthrotardigrada). Videnskabelige Meddelelser Dansk naturhistorisk Forening, 145, 201–218.

    Kristensen, R.M. & Hallas, T.E. (1980) The tidal genus Echiniscoides and its variability, with erection of Echiniscoididae fam. n. (Tardigrada). Zoologica Scripta, 9, 113–127.
    https://doi.org/10.1111/j.1463-6409.1980.tb00657.x

    Kristensen, R.M. & Hansen, J.G. (2005) Tardigrada (water bears) Ch. 5 Minor groups and fossils, In: Rohde, K. (Ed.), Marine Parasitology. CSIRO Publishing, Melburne, pp. 230–235.

    Kristensen, R.M. & Higgins, R.P. (1984a) Revision of Styraconyx (Tardigrada: Halechiniscidae), with description of two new species from Disko Bay, West Greenland. Smithsonian Contributions to Zoology, 391, 1–40.
    https://doi.org/10.5479/si.00810282.391

    Kristensen, R.M. & Higgins, R.P. (1984b) A new family of Arthrotardigrada (Tardigrada: Heterotardigrada) from the Atlantic Coast of Florida, U.S.A. Transactions of the American Microscopical Society, 103 (3), 295–311.
    https://doi.org/10.2307/3226191

    Kristensen, R.M. & Higgins, R.P. (1989) Marine Tardigrada from the southeastern United States coastal waters. I. Paradoxipus orzeliscoides n.gen., n.sp. (Arthrotardigrada: Halechiniscidae). Transactions of the American Microscopical Society, 108 (3), 262–282.
    https://doi.org/10.2307/3226344

    Kristensen, R.M. & Mackness, B.S. (2000) First record of the marine tardigrade genus Batillipes (Arthrotardigrada: Batillipedidae) from South Australia with a description of a new species. Records of the South Australian Museum, 33, 73–87.

    Kristensen, R.M. & Renaud-Mornant, J. (1983) Existence d’arthrotardigrades semi-benthiques de genres nouveaux de la sous-famille des Styraconyxinae subfam. nov. Cahiers de Biologie Marine, 24, 337–353.

    Kristensen, R.M., Sørensen, M.V., Hansen, J.G. & Zeppilli, D. (2015) A new species of Neostygarctus (Arthrotardigrada) from the Condor Seamount in the Azores, Northeast Atlantic. Marine Biodiversity, 45 (3), 453–467.
    https://doi.org/10.1007/s12526-015-0323-y

    Land, J. van der (1968) Florarctus antillensis, a new tardigrade from the coral sand of Curaçao. Studies on the Fauna of Curacao and other Caribbean Islands, 25, 140–146.

    Land, J. van der (1975) The parasitic marine tardigrade Tetrakentron synaptae. In: Higgins, R.P. (Ed.), International Symposium on Tardigrades. Memorie dell'Istituto Italiano di Idrobiologia, 32 (Supplement), 413–423.

    Lindgren, E.W. (1971) Psammolittoral marine tardigrades from North Carolina and their conformity to worldwide zonation patterns. Cahiers de Biologie Marine, 12, 481–496.

    Linnaeus, C. (1767) Systema Naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus & differentis, animale. Editio duodecima, reformata. Laurentius Salvius: Holmiae, II, 1–735.

    Marcus, E. (1927) Zur Anatomie und Ökologie mariner Tardigraden. Zoologische Jahrbücher Abteilung für Systematik, Ökologie und Geographie der Tiere, 53, 487–558.

    Marcus, E. (1936) Tardigrada. In: de Gruyter, W. (Ed.), Das Tierreich, 66, 1–340. [Berlin und Leipzig]

    Menechella, A.G., Bulnes, V.N. & Cazzaniga, N.J. (2015) A new Batillipedidae (Tardigrada. Arthrotardigrada) from Argentina. Zootaxa, 4032 (3), 339-344.
    https://doi.org/10.11646/zootaxa.4032.3.11

    Menechella, A.G., Bulnes, V.N. & Cazzaniga, N.J. (2017) Two new species of Batillipes (Tardigrada, Arthrotardigrada, Batillipedidae) from the Argentinean Atlantic coast, and a key to all known species. Marine Biodiversity, 1–9. [published online]
    https://doi.org/10.1007/s12526-017-0640-4

    McKirdy, D.J. (1975) Batillipes (Heterotardigrada): Comparison of six species from Florida (USA) and a discussion of taxonomic characters within the genus. Memorie dell’Istituto Italiano di Idrobiologia Pallanza, 32, 177–223.

    McKirdy, D.J., Schmidt, P. & McGinty-Bayly, M. (1976) Interstitielle Fauna von Galapagos. XVI. Tardigrada. Mikrofauna Meeresbodens, Mainz, 58, 409–449.

    Miller, W.R., Clark, T. & Miller, C. (2012) Tardigrades of North America: Archechiniscus biscaynei, nov. sp. (Arthrotardigrada, Archechiniscidae), a marine tardigrade from Biscayne National Park, Florida. Southeastern Naturalist, 11 (2), 279–286.
    https://doi.org/10.1656/058.011.0209

    Møbjerg, N., Kristensen, R.M. & Jørgensen, A. (2016) Data from new taxa infer Isoechiniscoides gen. nov. and increase the phylogenetic and evolutionary understanding of echiniscoidid tardigrades (Echiniscoidea: Tardigrada). Zoological Journal of the Linnean Society, 178, 804–818.
    https://doi.org/10.1111/zoj.12500

    Morgan, C.I., & O'Reilly, M. (1988) Additions to the Scottish tardigrade fauna, including a description of Megastygarctides setoloso new species, with a revised key for identification of Scottish marine species. Glasgow Naturalist, 21, 445–454.

    Morone De Lucia, M.R., Grimaldi de Zio, S. & D'Addabbo Gallo, M. (1984) Description of Parastygarctus biungulatus n. sp. and hypothesis of phylogeny in the Stygarctidae family (Heterotardigrada: Arthrotardigrada). Oebalia, 10, 85–94.

    Müller, O.F. (1776) Zoologica Danicae Prodromus seu Animalium Daniae et Norvegiae indigenarum characters, nomine, et synonyma imprimis popularium. Havniae, 32, 1–274.
    https://doi.org/10.5962/bhl.title.13268

    Nelson, D.R. & Marley, N. (2000) The biology and ecology of lotic Tardigrada. Freshwater Biology, 44, 93–108.
    https://doi.org/10.1046/j.1365-2427.2000.00586.x

    Nelson, D.R., Guidetti, R. & Rebecchi, L. (2015) Phylum Tardigrada. In: Thorp, J. & Rogers, D.C. (Eds.), Ecology and General Biology. Thorp and Covich’s Freshwater Invertebrates. Academic Press, New York, pp. 347–380.
    https://doi.org/10.1016/B978-0-12-385026-3.00017-6

    Perry, E.S. & Miller, W.R. (2015) Echiniscoides wyethi, a new marine tardigrade from Maine, U.S.A. (Heterotardigrada: Echiniscoidea: Echiniscoididae). Proceedings of the Biological Society of Washington, 128 (1), 103–110.
    https://doi.org/10.2988/0006-324X-128.1.103

    Pilato, G. & Binda, M.G. (2010) Definition of families, subfamilies, genera and subgenera of the Eutardigrada, and keys to their identification. Zootaxa, 2404, 1–54.

    Plate, L.H. (1889) Beiträge zur Naturgeschichte der Tardigraden. Zoologische Jahrbücher Abteillung für Anatomie und Ontogenie der Tiere, 3, 487–550.
    https://doi.org/10.5962/bhl.part.1265

    Pollock, L.W. (1970) Batillipes dicrocercus n. sp., Stygarctus granulatus n. sp. and other Tardigrada from Woods Hole, Massachusetts, U.S.A. Transactions of the American Microscopical Society, 89 (1), 38–52.
    https://doi.org/10.2307/3224613

    Pollock, L.W. (1971) On some British marine Tardigrada including two new species of Batillipes. Journal of the Marine Biological Association of the United Kingdom, 51, 93–103.
    https://doi.org/10.1017/S0025315400006482

    Pollock, L.W. (1975) Observations on marine Heterotardigrada including a new genus from the western Atlantic Ocean. Cahiers de Biologie Marine, 16, 121–132.

    Pollock, L.W. (1976) Marine flora and fauna of the northeastern United States. Tardigrada. National Oceanic and Atmospheric Administration Technical Report, National Marine Fisheries Service, Circular 394, 1–25.

    Pollock, L.W. (1979) Angursa bicuspis n. sp., a marine arthrotardigrade from the western North Atlantic. Transactions of the American Microscopical Society, 98, 558–565.
    https://doi.org/10.2307/3225907

    Pollock, L.W. (1982) A closer look at some marine Heterotardigrada. I. The morphology and taxonomy of Orzeliscus. In: Nelson, D. (Ed.), Proceedings of the Third International Symposium on Tardigrada. East Tennessee State University Press, Johnson City, Tennessee, pp. 193–202.

    Pollock, L.W. (1983) A closer look at some marine Heterotardigrada. II. The morphology and taxonomy of Bathyechiniscus, with the description of B. craticulus n. sp. from the Caribbean. Bulletin of Marine Science, 33 (1), 109–117.

    Pollock, L.W. (1989) Marine interstitial Heterotardigrada from the Pacific Coast of the United States, including a description of Batillipes tridentatus n. sp. Transactions of the American Microscopical Society, 108 (2), 169–189.
    https://doi.org/10.2307/3226373

    Pollock, L.W. (1995) New marine tardigrades from Hawaiian beach sand and phylogeny of the family Halechiniscidae. Invertebrate Biology, 114 (3), 220–235.
    https://doi.org/10.2307/3226877

    Rahm, G. (1937) A new ordo [sic] of tardigrades from the hot springs of Japan (Furu-yu Section, Unzen). Annotationes Zoologicae Japonensis, 16, 345–352.

    Ramazzotti, G. (1962) Il Phylum Tardigrada. Memorie dell'Istituto Italiano di Idrobiologia, 14, 1–595.

    Ramazzotti, G. (1972) Tardigradi delle Isole Kerguelen e descrizione della nuova specie Hypsibius (I.) renaudi. Memorie dell'Istituto Italiano di Idrobiologia, 29, 141–144.

    Ramazzotti, G. & Maucci, W. (1983) Il Phylum Tardigrada - III edizione. Memorie dell'Istituto Italiano di Idrobiologia, 41, 1–1012.

    Rathke, J. (1799) Jattagelser henhørende til Indvoldeormenes og Bløddyrenes Naturhistorie. Skrivter af Naturhistorie- Selskabet, Kiøbenhavn, 5 (1), 61–153.

    Renaud-Debyser, J. (1959) Études sur la faune interstitielle des Îles Bahamas. III: Tardigrades. Vie et Milieu, 10, 297–302.

    Renaud-Debyser, J. (1965) Étude sur un Stygarctidae (Tardigrada) nouveau de Madagascar. Bulletin de la Societé Zoologique de France, 90, 31–38.

    Renaud-Mornant, J. (1974) Une nouvelle famille de Tardigrades marins abyssaux: Coronarctidae fam. nov. (Heterotardigrada). Comptes Rendus de l’Académie des sciences, Série D, 278, 3087–3090.

    Renaud-Mornant, J. (1975a) Deep Sea Tardigrada from «Meteor» Indian Ocean Expedition. «Meteor» Forschungen-Ergnisse, Series D, 21, 54–61.

    Renaud-Mornant, J. (1975b) Occurrence of the genus Tanarctus Renaud-Debyser, 1959 in North Eastern Atlantic waters with a description of T. ramazzotti n. sp. (Arthrotardigrada). Memorie dell’Istituto Italiano di Idrobiologia Pallanza, 32, 325–332.

    Renaud-Mornant, J. (1976) Le genre Florarctus Delamare-Deboutteville et Renaud-Mornant, 1965, en Mediterrannée, description de deux espèces nouvelles (Arthrotardigrada). Bulletin du Muséum National d’Histoire Naturelle (Paris), 369, 325–333.

    Renaud-Mornant, J. (1979a) Tardigrades marins de Madagascar. I. Halechiniscidae et Batillipedidae. Bulletin du Muséum National d'Histoire Naturelle, Paris, Série 4e, 1 (Section A, nº 1), 257–277.

    Renaud-Mornant, J. (1979b) Tardigrades marins de Madagascar. II. Stygarctidae et Oreellidae. III. Considérations écologiques générales. Bulletin du Muséum National d’Histoire Naturelle (Paris), Série 4e, 1 (Section A, nº 2), 3, 339–351.

    Renaud-Mornant, J. (1980) Description de trois espèces nouvelles du genre Tanarctus Renaud-Debyser 1959, et création de la sous-famille des Tanarctinae, subfam. nov. (Tardigrada, Heterotardigrada). Bulletin du Muséum National d’Histoire Naturelle (Paris), 2 (1), 129–142.

    Renaud-Mornant, J. (1981a) Raiarctus colurus n.g., n.sp., et R. aureolatus n.sp., Tardigrades (Arthrotardigrada) marins nouveaux de sédiments calcaires. Bulletin du Muséum National d’Histoire Naturelle (Paris), Série 4e, 3 (Section A, nº 2), 515–522.

    Renaud-Mornant, J. (1981b) Deux nouveaux Angursa Pollock, 1979, du domaine abyssal (Tardigrada, Arthrotardigrada). Tethys, 10, 161–164.

    Renaud-Mornant, J. (1982a) Species diversity in marine Tardigrada. In: Nelson, D. (Ed.), Proceedings of the Third International Symposium on Tardigrada. East Tennessee State University Press, Johnson City, Tennessee, 149–177.

    Renaud-Mornant, J. (1982b) Sous-famille et genre nouveaux de Tardigrades marins (Arthrotardigrada). Bulletin du Muséum National d’Histoire Naturelle, Paris, Série 4e, (Section A, nº 1–2), 89–94.

    Renaud-Mornant, J. (1983) Tardigrades abyssaux nouveaux de la sous-famille des Euclavarctinae n. subfam. (Arthrotardigrada, Halechiniscidae) Bulletin du Muséum National d’Histoire Naturelle (Paris), Séries 4e, 5e (Section A, nº 1), 201–219.

    Renaud-Mornant, J. (1984) Halechiniscidae (Heterotardigrada) de la campagne Benthedi, canal du Mozambique. Bulletin du Muséum National d’Histoire Naturelle (Paris), Séries 4e, 6e (Section A, nº 1), 67–88.

    Renaud-Mornant, J. (1987a) Halechiniscidae nouveaux de sables coralliens tropicaux (Tardigrada, Arthrotardigrada). Bulletin du Muséum National d’Histoire Naturelle, Paris, 9 (2), 353–373.

    Renaud-Mornant, J. (1987b) Bathyal and abyssal Coronarctidae (Tardigrada), description of new species and phylogenetical significance. In: Bertolani, R. (Ed.), Biology of Tardigrades. Selected Symposia and Monographs U.Z.I. 1. Mucchi Editore, Modena, pp. 229–252.

    Renaud-Mornant, J. (1989a) Espèces nouvelles de Florarctinae de l’Atlantique Nord-Est et du Pacifique Sud (Tardigrada, Arthrotardigrada). Bulletin du Muséum National d'Histoire Naturelle, Paris, Série 4e, 11 (Section A, nº 3), 571–592.

    Renaud-Mornant, J. (1989b) Opydorscus, un nouveau genre d’Orzeliscinae et sa signification phylogénique (Tardigrada, Arthrotardigrada). Bulletin du Muséum National d’Histoire Naturelle, Paris, Série 4e, 11 (Section A, nº 4), 763–771.

    Rho, H.S., Min, B.H. & Chang, C.Y. (1999) Taxonomic study of marine tardigrades from Korea. I Genus Batillipes (Heterotardigrada: Batillipedidae). The Korean Journal of Systematic Zoology, 15 (1), 107–118.

    Richters, F. (1908) Marine Tardigraden. Zoologischer Anzeiger, 33, 77–85.

    Richters, F. (1909) Tardigraden-Studien. Bericht der Senckenbergzischen Naturforschenden Gesellschaft in Frankfurt am Main, 1–2, 28–49.

    Richters, F. (1926) Tardigrada. In: Kükentahl, W. & Krumbach, T. (Eds.), Handbuch der Zoologie. Vol. 3. Walter de Gruyter & Co., Berlin and Leipzig, pp. 58–61.

    Romano III, F., Gallo, M., D’Addabbo, R., Accogli, G., Bagueley, J. & Montagna, P. (2011) Deep-sea tardigrades in the northern Gulf of Mexico with a description of a new species of Coronarctidae (Tardigrada: Arthrotardigrada), Coronarctus mexicus. Journal of Zoological Systematics and Evolutionary Research, 49 (Supplement 1), 48–52.
    https://doi.org/10.1111/j.1439-0469.2010.00597.x

    Rubal, M., Veiga, P., Fontoura, P. & Sousa-Pinto, I. (2013) A new intertidal arthrotardigrade, Prostygarctus aculeatus gen. nov., sp. nov. (Tardigrada: Heterotardigrada) from the north of Portugal (Atlantic Ocean). Journal of Limnology, 72 (Supplement 1), 8–14.
    https://doi.org/10.4081/jlimnol.2013.s1.e2

    Rubal, M., Veiga, P., Fontoura, P. & Sousa-Pinto, I. (2016) A new Batillipes (Tardigrada, Heterotardigrada, Batillipedidae) from North Portugal (Atlantic Ocean). Marine Biodiversity. [published online]
    https://doi10.1007/s12526-016-0526-x

    Schulz, E. (1935) Actinarctus doryphorus nov. gen. nov. spec., ein merkwürdiger Tardigrad aus der Nordsee. Zoologischer Anzeiger, 111, 285–288.

    Schulz, E. (1951) Über Stygarctus bradypus n.g., s.p., einen Tardigraden aus dem Küstengrundwasser und seine phylogenetische Bedeutung. Kieler Meeresforschung, 8, 86–97.

    Schulz, E. (1953) Ein neue Tardigraden-Gattung von der pacifischen Küste. Zoologischer Anzeiger, 151, 306–310.

    Schulz, E. (1955) Studien an marinen Tardigraden. Kieler Meeresforschung, 11, 73–79.

    Schulz, E. (1963) Über die Tardigraden. Zoologischer Anzeiger, 171, 3–12.

    Schultze, M. (1865) Echiniscus sigismundi, ein Arctiscoide der Nordsee. Archiv für Mikroskopische Anatomie, 1, 1, 428–436. https:// doi.org:10.1007/BF02961427

    Schuster, R.O., Nelson, D.R., Grigarick, A.A. & Christenberry, D. (1980) Systematic criteria of the Eutardigrada. Transactions of the American Microscopical Society, 99 (3), 284–303.
    https://doi.org/10.2307/3226004

    Steiner, G. (1926) Bathyechiniscus tetronyx n. g. n. sp. Ein neuer mariner Tardigrade. Deutschen Südpolar-Expedition, 18, 1–10.

    Thulin, G. (1928) Über die Phylogenie und das System der Tardigraden. Hereditas Genetiskt Arkiv, 11, 207–266.
    https://doi.org/10.1111/j.1601-5223.1928.tb02488.x

    Thulin, G. (1942) Ein neuer mariner Tardigrad. Meddelanden från Göteborgs Musei Zoologiska Avdelning, 99, 1–10.

    Tsurusaki, N. (1980) A new species of marine interstitial Tardigrada of the genus Hypsibius from Hokkaido, northern Japan, Annotationes Zoologicae Japonense, 53 (4), 280–284.

    Villora-Moreno, S. (1996) A new genus and species of deep-sea family Coronarctidae (Tardigrada) from a submarine cave with a deep-sea like condition. Sarsia, 81, 275–283.
    https://doi.org/10.1080/00364827.1996.10413625

    Villora-Moreno, S. (1998) Deep-sea Tardigrada from South Shetland Islands (Antarctica) with description of Angursa antarctica sp. nov. (Arthrotardigrada, Halechiniscidae). Polar Biology, 19, 336–341.
    https://doi.org/10.1007/s003000050255