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Kihm JH, Smith FW, Kim S, Rho HS, Zhang X, Liu J, Park TYS. Cambrian lobopodians shed light on the origin of the tardigrade body plan. Proc Natl Acad Sci U S A 2023; 120:e2211251120. [PMID: 37399417 PMCID: PMC10334802 DOI: 10.1073/pnas.2211251120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Accepted: 05/22/2023] [Indexed: 07/05/2023] Open
Abstract
Phylum Tardigrada (water bears), well known for their cryptobiosis, includes small invertebrates with four paired limbs and is divided into two classes: Eutardigrada and Heterotardigrada. The evolutionary origin of Tardigrada is known to lie within the lobopodians, which are extinct soft-bodied worms with lobopodous limbs mostly discovered at sites of exceptionally well-preserved fossils. Contrary to their closest relatives, onychophorans and euarthropods, the origin of morphological characters of tardigrades remains unclear, and detailed comparison with the lobopodians has not been well explored. Here, we present detailed morphological comparison between tardigrades and Cambrian lobopodians, with a phylogenetic analysis encompassing most of the lobopodians and three panarthropod phyla. The results indicate that the ancestral tardigrades likely had a Cambrian lobopodian-like morphology and shared most recent ancestry with the luolishaniids. Internal relationships within Tardigrada indicate that the ancestral tardigrade had a vermiform body shape without segmental plates, but possessed cuticular structures surrounding the mouth opening, and lobopodous legs terminating with claws, but without digits. This finding is in contrast to the long-standing stygarctid-like ancestor hypothesis. The highly compact and miniaturized body plan of tardigrades evolved after the tardigrade lineage diverged from an ancient shared ancestor with the luolishaniids.
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Affiliation(s)
- Ji-Hoon Kihm
- Division of Earth Sciences, Korea Polar Research Institute, Yeonsu-gu, Incheon21990, Korea
| | - Frank W. Smith
- Department of Biology, University of North Florida, Jacksonville, FL32224
| | - Sanghee Kim
- Division of Life Sciences, Korea Polar Research Institute, Yeonsu-gu, Incheon21990, Korea
| | - Hyun Soo Rho
- East Sea Environment Research Center, East Sea Research Institute, Korea Institute of Ocean Science and Technology, Uljin, Gyeongsangbuk-do36315, Korea
| | - Xingliang Zhang
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi’an710069, China
| | - Jianni Liu
- State Key Laboratory of Continental Dynamics, Shaanxi Key Laboratory of Early Life and Environments, Department of Geology, Northwest University, Xi’an710069, China
| | - Tae-Yoon S. Park
- Division of Earth Sciences, Korea Polar Research Institute, Yeonsu-gu, Incheon21990, Korea
- Polar Science, University of Science and Technology, Yuseong-gu, Daejeon34113, Korea
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Bartels PJ, Nelson DR. Do marine sponges host epizoic tardigrades? CARIBB J SCI 2020. [DOI: 10.18475/cjos.v50i1.a8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Paul J. Bartels
- Department of Biology, Warren Wilson College, Asheville, North Carolina, U. S. A
| | - Diane R. Nelson
- Department of Biological Sciences, East Tennessee State University, Johnson City, Tennessee, U. S. A
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Abstract
Recent discoveries of fossil nervous tissue in Cambrian fossils have allowed researchers to trace the origin and evolution of the complex arthropod head and brain based on stem groups close to the origin of the clade, rather than on extant, highly derived members. Here we show that Kerygmachela from Sirius Passet, North Greenland, a primitive stem-group euarthropod, exhibits a diminutive (protocerebral) brain that innervates both the eyes and frontal appendages. It has been surmised, based on developmental evidence, that the ancestor of vertebrates and arthropods had a tripartite brain, which is refuted by the fossil evidence presented here. Furthermore, based on the discovery of eyes in Kerygmachela, we suggest that the complex compound eyes in arthropods evolved from simple ocelli, present in onychophorans and tardigrades, rather than through the incorporation of a set of modified limbs. The arthropod head is complex and its evolution has been difficult to reconstruct. Here, Park et al. describe new specimens of the Cambrian stem-group euarthropod Kerygmachela that preserve evidence of primitive compound eyes and a unipartite brain, providing insight into the structure of the early arthropod head.
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Møbjerg N, Jørgensen A, Kristensen RM, Neves RC. Morphology and Functional Anatomy. WATER BEARS: THE BIOLOGY OF TARDIGRADES 2018. [DOI: 10.1007/978-3-319-95702-9_2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Smith FW, Goldstein B. Segmentation in Tardigrada and diversification of segmental patterns in Panarthropoda. ARTHROPOD STRUCTURE & DEVELOPMENT 2017; 46:328-340. [PMID: 27725256 DOI: 10.1016/j.asd.2016.10.005] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 08/11/2016] [Accepted: 10/03/2016] [Indexed: 05/03/2023]
Abstract
The origin and diversification of segmented metazoan body plans has fascinated biologists for over a century. The superphylum Panarthropoda includes three phyla of segmented animals-Euarthropoda, Onychophora, and Tardigrada. This superphylum includes representatives with relatively simple and representatives with relatively complex segmented body plans. At one extreme of this continuum, euarthropods exhibit an incredible diversity of serially homologous segments. Furthermore, distinct tagmosis patterns are exhibited by different classes of euarthropods. At the other extreme, all tardigrades share a simple segmented body plan that consists of a head and four leg-bearing segments. The modular body plans of panarthropods make them a tractable model for understanding diversification of animal body plans more generally. Here we review results of recent morphological and developmental studies of tardigrade segmentation. These results complement investigations of segmentation processes in other panarthropods and paleontological studies to illuminate the earliest steps in the evolution of panarthropod body plans.
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Affiliation(s)
- Frank W Smith
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
| | - Bob Goldstein
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
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Fujimoto S, Jørgensen A, Hansen JG. A molecular approach to arthrotardigrade phylogeny (Heterotardigrada, Tardigrada). ZOOL SCR 2016. [DOI: 10.1111/zsc.12221] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Shinta Fujimoto
- Department of Zoology; Division of Biological Science; Graduate School of Science; Kyoto University; Kitashirakawa-Oiwakecho Sakyo-ku Kyoto 606-8502 Japan
- Research Center for Marine Biology; Graduate School of Life Sciences; Tohoku University; Kyoto University; 9 Sakamoto Asamushi Aomori 039-3501 Japan
| | - Aslak Jørgensen
- Department of Biology; August Krogh Centre; University of Copenhagen; Universitetsparken 13; DK-2100 Copenhagen Ø Denmark
| | - Jesper G. Hansen
- Natural History Museum of Denmark; University of Copenhagen; Universitetsparken 15; DK-2100 Copenhagen Ø Denmark
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Morek W, Stec D, Gąsiorek P, Schill RO, Kaczmarek Ł, Michalczyk Ł. An experimental test of eutardigrade preparation methods for light microscopy. Zool J Linn Soc 2016. [DOI: 10.1111/zoj.12457] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Witold Morek
- Department of Entomology; Institute of Zoology; Jagiellonian University; Gronostajowa 9 30-387 Kraków Poland
| | - Daniel Stec
- Department of Entomology; Institute of Zoology; Jagiellonian University; Gronostajowa 9 30-387 Kraków Poland
| | - Piotr Gąsiorek
- Department of Entomology; Institute of Zoology; Jagiellonian University; Gronostajowa 9 30-387 Kraków Poland
| | - Ralph O. Schill
- Department of Zoology; Institute of Biomaterials and Biomolecular Systems; Stuttgart University; Stuttgart Germany
| | - Łukasz Kaczmarek
- Department of Animal Taxonomy and Ecology; Adam Mickiewicz University; Umultowska 89 61-614 Poznań Poland
| | - Łukasz Michalczyk
- Department of Entomology; Institute of Zoology; Jagiellonian University; Gronostajowa 9 30-387 Kraków Poland
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Gross V, Mayer G. Neural development in the tardigrade Hypsibius dujardini based on anti-acetylated α-tubulin immunolabeling. EvoDevo 2015; 6:12. [PMID: 26052416 PMCID: PMC4458024 DOI: 10.1186/s13227-015-0008-4] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Accepted: 04/02/2015] [Indexed: 12/15/2022] Open
Abstract
Background The tardigrades (water bears) are a cosmopolitan group of microscopic ecdysozoans found in a variety of aquatic and temporarily wet environments. They are members of the Panarthropoda (Tardigrada + Onychophora + Arthropoda), although their exact position within this group remains contested. Studies of embryonic development in tardigrades have been scarce and have yielded contradictory data. Therefore, we investigated the development of the nervous system in embryos of the tardigrade Hypsibius dujardini using immunohistochemical techniques in conjunction with confocal laser scanning microscopy in an effort to gain insight into the evolution of the nervous system in panarthropods. Results An antiserum against acetylated α-tubulin was used to visualize the axonal processes and general neuroanatomy in whole-mount embryos of the eutardigrade H. dujardini. Our data reveal that the tardigrade nervous system develops in an anterior-to-posterior gradient, beginning with the neural structures of the head. The brain develops as a dorsal, bilaterally symmetric structure and contains a single developing central neuropil. The stomodeal nervous system develops separately and includes at least four separate, ring-like commissures. A circumbuccal nerve ring arises late in development and innervates the circumoral sensory field. The segmental trunk ganglia likewise arise from anterior to posterior and establish links with each other via individual pioneering axons. Each hemiganglion is associated with a number of peripheral nerves, including a pair of leg nerves and a branched, dorsolateral nerve. Conclusions The revealed pattern of brain development supports a single-segmented brain in tardigrades and challenges previous assignments of homology between tardigrade brain lobes and arthropod brain segments. Likewise, the tardigrade circumbuccal nerve ring cannot be homologized with the arthropod ‘circumoral’ nerve ring, suggesting that this structure is unique to tardigrades. Finally, we propose that the segmental ganglia of tardigrades and arthropods are homologous and, based on these data, favor a hypothesis that supports tardigrades as the sister group of arthropods. Electronic supplementary material The online version of this article (doi:10.1186/s13227-015-0008-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Vladimir Gross
- Animal Evolution and Development, Institute of Biology, University of Leipzig, Talstraße 33, 04103 Leipzig, Germany ; Department of Zoology, Institute of Biology, University of Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany
| | - Georg Mayer
- Department of Zoology, Institute of Biology, University of Kassel, Heinrich-Plett-Str. 40, D-34132 Kassel, Germany
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Fujimoto S. Halechiniscidae (Heterotardigrada, Arthrotardigrada) of Oura Bay, Okinawajima, Ryukyu Islands, with descriptions of three new species. Zookeys 2015:149-66. [PMID: 25755627 PMCID: PMC4351450 DOI: 10.3897/zookeys.483.8936] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 02/09/2015] [Indexed: 11/28/2022] Open
Abstract
Marine tardigrades of the family Halechiniscidae (Heterotardigrada: Arthrotardigrada) are reported from Oura Bay, Okinawajima, one of the Ryukyu Islands, Japan, including Dipodarctus sp., Florarctuswunaisp. n., Halechiniscuschurakaagiisp. n., Halechiniscusyanakaagiisp. n. and Styraconyx sp. The attributes distinguishing Florarctuswunaisp. n. from its congeners is a combination of two characters, the smooth dorsal cuticle and two small projections of the caudal alae caestus. Halechiniscuschurakaagiisp. n. is differentiated from its congeners by the combination of two characters, the robust cephalic cirrophores and the scapular processes with flat oval tips, while Halechiniscusyanakaagiisp. n. can be identified by the laterally protruded arched double processes with acute tips situated dorsally at the level of leg I. A list of marine tardigrades reported from the Ryukyu Islands is provided.
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Affiliation(s)
- Shinta Fujimoto
- Department of Zoology, Division of Biological Science, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502, Japan
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Smith FW, Jockusch EL. The metameric pattern of Hypsibius dujardini(Eutardigrada) and its relationship to that of other panarthropods. Front Zool 2014. [DOI: 10.1186/s12983-014-0066-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
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Schulze C, Neves RC, Schmidt-Rhaesa A. Comparative immunohistochemical investigation on the nervous system of two species of Arthrotardigrada (Heterotardigrada, Tardigrada). ZOOL ANZ 2014. [DOI: 10.1016/j.jcz.2013.11.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Mayer G, Martin C, Rüdiger J, Kauschke S, Stevenson PA, Poprawa I, Hohberg K, Schill RO, Pflüger HJ, Schlegel M. Selective neuronal staining in tardigrades and onychophorans provides insights into the evolution of segmental ganglia in panarthropods. BMC Evol Biol 2013; 13:230. [PMID: 24152256 PMCID: PMC4015553 DOI: 10.1186/1471-2148-13-230] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 10/16/2013] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Although molecular analyses have contributed to a better resolution of the animal tree of life, the phylogenetic position of tardigrades (water bears) is still controversial, as they have been united alternatively with nematodes, arthropods, onychophorans (velvet worms), or onychophorans plus arthropods. Depending on the hypothesis favoured, segmental ganglia in tardigrades and arthropods might either have evolved independently, or they might well be homologous, suggesting that they were either lost in onychophorans or are a synapomorphy of tardigrades and arthropods. To evaluate these alternatives, we analysed the organisation of the nervous system in three tardigrade species using antisera directed against tyrosinated and acetylated tubulin, the amine transmitter serotonin, and the invertebrate neuropeptides FMRFamide, allatostatin and perisulfakinin. In addition, we performed retrograde staining of nerves in the onychophoran Euperipatoides rowelli in order to compare the serial locations of motor neurons within the nervous system relative to the appendages they serve in arthropods, tardigrades and onychophorans. RESULTS Contrary to a previous report from a Macrobiotus species, our immunocytochemical and electron microscopic data revealed contralateral fibres and bundles of neurites in each trunk ganglion of three tardigrade species, including Macrobiotus cf. harmsworthi, Paramacrobiotus richtersi and Hypsibius dujardini. Moreover, we identified additional, extra-ganglionic commissures in the interpedal regions bridging the paired longitudinal connectives. Within the ganglia we found serially repeated sets of serotonin- and RFamid-like immunoreactive neurons. Furthermore, our data show that the trunk ganglia of tardigrades, which include the somata of motor neurons, are shifted anteriorly with respect to each corresponding leg pair, whereas no such shift is evident in the arrangement of motor neurons in the onychophoran nerve cords. CONCLUSIONS Taken together, these data reveal three major correspondences between the segmental ganglia of tardigrades and arthropods, including (i) contralateral projections and commissures in each ganglion, (ii) segmentally repeated sets of immunoreactive neurons, and (iii) an anteriorly shifted (parasegmental) position of ganglia. These correspondences support the homology of segmental ganglia in tardigrades and arthropods, suggesting that these structures were either lost in Onychophora or, alternatively, evolved in the tardigrade/arthropod lineage.
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Affiliation(s)
- Georg Mayer
- Animal Evolution and Development, Institute of Biology, University of Leipzig, Talstraße 33, D-04103 Leipzig, Germany
| | - Christine Martin
- Animal Evolution and Development, Institute of Biology, University of Leipzig, Talstraße 33, D-04103 Leipzig, Germany
| | - Jan Rüdiger
- Animal Evolution and Development, Institute of Biology, University of Leipzig, Talstraße 33, D-04103 Leipzig, Germany
| | - Susann Kauschke
- Animal Evolution and Development, Institute of Biology, University of Leipzig, Talstraße 33, D-04103 Leipzig, Germany
| | - Paul A Stevenson
- Physiology of Animals and Behavior, Institute of Biology, University of Leipzig, Talstraße 33,D-04103 Leipzig, Germany
| | - Izabela Poprawa
- Department of Animal Histology and Embryology, University of Silesia, Bankowa 9, 40-007 Katowice, Poland
| | - Karin Hohberg
- Senckenberg Museum of Natural History Görlitz, Am Museum 1, D-02826 Görlitz, Germany
| | - Ralph O Schill
- Biological Institute, Zoology, University of Stuttgart, Pfaffenwaldring 57, D-70569 Stuttgart, Germany
| | - Hans-Joachim Pflüger
- Neurobiology, Institute of Biology, Freie Universität Berlin, Königin-Luise-Str. 28-30, D-14195 Berlin, Germany
| | - Martin Schlegel
- Molecular Evolution & Animal Systematics, Institute of Biology, University of Leipzig, Talstraße 33, D-04103 Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv), Halle-Jena-Leipzig, Deutscher Platz 5e, D-04103 Leipzig, Germany
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Persson DK, Halberg KA, Jørgensen A, Møbjerg N, Kristensen RM. Brain anatomy of the marine tardigradeactinarctus doryphorus(arthrotardigrada). J Morphol 2013; 275:173-90. [DOI: 10.1002/jmor.20207] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2013] [Revised: 07/01/2013] [Accepted: 08/19/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Dennis K. Persson
- Department of Invertebrate Zoology, Natural History Museum of Denmark; University of Copenhagen, Universitetsparken 15; DK-2100 Copenhagen Ø Denmark
- Department of Biology, August Krogh Centre; University of Copenhagen, Universitetsparken 13; DK-2100 Copenhagen Ø Denmark
| | - Kenneth A. Halberg
- Department of Biology, August Krogh Centre; University of Copenhagen, Universitetsparken 13; DK-2100 Copenhagen Ø Denmark
| | - Aslak Jørgensen
- Laboratory of Molecular Systematics, Natural History Museum of Denmark; University of Copenhagen; Sølvgade 83 DK-1307 Copenhagen K Denmark
| | - Nadja Møbjerg
- Department of Biology, August Krogh Centre; University of Copenhagen, Universitetsparken 13; DK-2100 Copenhagen Ø Denmark
| | - Reinhardt M. Kristensen
- Department of Invertebrate Zoology, Natural History Museum of Denmark; University of Copenhagen, Universitetsparken 15; DK-2100 Copenhagen Ø Denmark
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Fujimoto S, Miyazaki K. Neostygarctus lovedeluxe n. sp. from the Miyako Islands, Japan: the first record of Neostygarctidae (Heterotardigrada: Arthrotardigrada) from the Pacific. Zoolog Sci 2013; 30:414-9. [PMID: 23646947 DOI: 10.2108/zsj.30.414] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A new species of the previously monospecific marine tardigrade family Neostygarctidae is described. Neostygarctus lovedeluxe n. sp. was found from a submarine cave in Miyako Islands, Japan. This is the first record of Neostygarctidae from the Pacific. The new species is easily distinguished from the previously known N. acanthophorus by its number of dorsal spines, as N. lovedeluxe has two spines each on the three dorsal body plates in contrast to one in N. acanthophorus. Furthermore the morphology of the two clawed juvenile is reported for the first time in Neostygarctidae, providing new insights into the common sequence in some ontogenic traits.
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Affiliation(s)
- Shinta Fujimoto
- Department of Zoology, Division of Biological Science, Graduate School of Science, Kyoto University, Japan
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Persson DK, Halberg KA, Jørgensen A, Møbjerg N, Kristensen RM. Neuroanatomy ofHalobiotus crispae(Eutardigrada: Hypsibiidae): Tardigrade brain structure supports the clade panarthropoda. J Morphol 2012; 273:1227-45. [DOI: 10.1002/jmor.20054] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2011] [Revised: 04/26/2012] [Accepted: 05/27/2012] [Indexed: 12/18/2022]
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Calloway S, Miller WR, Johansson C, Whiting J. Tardigrades of North America: Oreella chugachii, a new species (Heterotardigrada, Echiniscoide, Oreellidae) from Alaska. P BIOL SOC WASH 2011. [DOI: 10.2988/10-08.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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Jørgensen A, Faurby S, Hansen JG, Møbjerg N, Kristensen RM. Molecular phylogeny of Arthrotardigrada (Tardigrada). Mol Phylogenet Evol 2010; 54:1006-15. [DOI: 10.1016/j.ympev.2009.10.006] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2009] [Revised: 10/01/2009] [Accepted: 10/05/2009] [Indexed: 10/20/2022]
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Sands CJ, McInnes SJ, Marley NJ, Goodall-Copestake WP, Convey P, Linse K. Phylum Tardigrada: an “individual” approach. Cladistics 2008; 24:861-871. [DOI: 10.1111/j.1096-0031.2008.00219.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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WIEDERHÖFT HOLGER, GREVEN HARTMUT. The cerebral ganglia of Milnesium tardigradum Doyère (Apochela, Tardigrada): Three dimensional reconstruction and notes on their ultrastructure. Zool J Linn Soc 2008. [DOI: 10.1111/j.1096-3642.1996.tb02334.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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DEWEL RUTHANN, DEWEL WILLIAMC. The brain of Echiniscus viridissimus Peterfi, 1956 (Heterotardigrada): a key to understanding the phylogenetic position of tardigrades and the evolution of the arthropod head. Zool J Linn Soc 2008. [DOI: 10.1111/j.1096-3642.1996.tb02331.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Three-dimensional reconstruction of the central nervous system of Macrobiotus hufelandi (Eutardigrada, Parachela): implications for the phylogenetic position of Tardigrada. ZOOMORPHOLOGY 2007. [DOI: 10.1007/s00435-007-0045-1] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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23
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Jørgensen A, Kristensen RM. Molecular phylogeny of Tardigrada—investigation of the monophyly of Heterotardigrada. Mol Phylogenet Evol 2004; 32:666-70. [PMID: 15223045 DOI: 10.1016/j.ympev.2004.04.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2003] [Revised: 04/23/2004] [Indexed: 11/24/2022]
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24
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Hansen JG, Jørgensen A, Kristensen RM. Preliminary Studies of the Tardigrade Fauna of the Faroe Bank. ZOOL ANZ 2001. [DOI: 10.1078/0044-5231-00046] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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de Zio Grimaldi S, Gallo MD, Lucia MRM. Neoarctus primigeniusn. g., n. sp., a new Stygarctidae of the Tyrrhenian Sea (Tardigrada, Arthrotardigrada). ACTA ACUST UNITED AC 1992. [DOI: 10.1080/11250009209386687] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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BUSSAU CHRISTIAN. New deep-sea Tardigrada (Arthrotardigrada, Halechiniscidae) from a manganese nodule area of the eastern South Pacific*. ZOOL SCR 1992. [DOI: 10.1111/j.1463-6409.1992.tb00311.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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de Zio SG, Gallo MD, de Lucia MRM, Daddabbo L. Marine Arthrotardigrada and Echiniscoidea (Tardigrada, Heterotardigrada) from the Indian Ocean. ACTA ACUST UNITED AC 1987. [DOI: 10.1080/11250008709355608] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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