Molecular phylogeny of Arthrotardigrada (Tardigrada)

Jørgensen, Aslak; Faurby, Søren; Hansen, Jesper Guldberg; Møbjerg, Nadja; Kristensen, Reinhardt Møbjerg

doi:10.1016/j.ympev.2009.10.006

Cited by 88 publications

(88 citation statements)

References 32 publications

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“…Neither the phylogeny within Tardigrada nor the relationships to other taxa are totally resolved. The taxon is classified into the two probably monophyletic groups Heterotardigrada and Eutardigrada (Nichols et al, 2006;Jørgensen et al, 2010). A third taxon, the Mesotardigrada, has been described by Rahm in 1937 (Rahm, 1937a(Rahm, , 1937b, but since then has never been found again (Ramazzotti and Maucci, 1983;Kinchin, 1994).…”

Section: Introductionmentioning

confidence: 99%

“…The Heterotardigrada and the Eutardigrada are divided into two taxa each, the Arthrotardigrada and the Echiniscoidea, and the Apochela and the Parachela, respectively. This traditional classification is based on morphological data (Marcus, 1929;Schuster et al, 1980;Ramazzotti and Maucci, 1983), but the validity of these taxa is still under discussion (Jørgensen and Kristensen, 2004;Sands et al, 2008;Guidetti et al, 2009;Jørgensen et al, 2010Jørgensen et al, , 2011Guil and Giribet, 2012). The Tardigrada possess morphological features that show similarities to both Panarthropoda (including Arthropoda and Onychophora) and Nematoda (Crowe et al, 1970;Dewel and Clark, 1973a, 1973b, 1973cSchmidt-Rhaesa et al, 1998;Giribet, 2003).…”

Section: Introductionmentioning

confidence: 99%

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The architecture of the nervous system of Echiniscus testudo (Echiniscoidea, Heterotardigrada)

Schulze

Schmidt‐Rhaesa

2013

J Limnol

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The architecture of the nervous system of Echiniscus testudo (Echiniscoidea, Heterotardigrada)

Schulze

Schmidt‐Rhaesa

2013

J Limnol

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“…Compared with the limno-terrestrial parachelan eutardigrades, the ionic composition of this heterotardigrade is characterized by a large contribution of Na + and Cl -(~45%), and a very low contribution of Mg 2+ (0.4%), SO 4 2-(0.6%) and PO 4 3-(1.4%) (Table5). The large contribution of Na + and Cl -to total osmotic concentration, which is comparable to that seen in the secondarily marine eutardigrade H. crispae (Table5), could reflect the marine origin of tardigrades (Jørgensen et al, 2010).…”

Section: Ionic Composition In Tardigradesmentioning

confidence: 66%

Inorganic ion composition in Tardigrada: cryptobionts contain large fraction of unidentified organic solutes

Halberg

Larsen

Jørgensen

et al. 2012

Journal of Experimental Biology

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Summary Many species of tardigrades are known to tolerate extreme environmental stress, yet detailed knowledge of the mechanisms underlying the remarkable adaptations of tardigrades is still lacking, as are answers to many questions regarding their basic biology. Here, we present data on the inorganic ion composition and total osmotic concentration of five different species of tardigrades (Echiniscus testudo, Milnesium tardigradum, Richtersius coronifer, Macrobiotus cf. hufelandi and Halobiotus crispae) using high-performance liquid chromatography and nanoliter osmometry. Quantification of the ionic content indicates that Na+ and Cl- are the principle inorganic ions in tardigrade fluids, albeit other ions, i.e. K+, NH4+, Ca2+, Mg2+, F-, SO42- and PO43- were also detected. In limno-terrestrial tardigrades, the respective ions are concentrated by a large factor compared to that of the external medium (Na+, ×70-800; K+, ×20-90; Ca2+ and Mg2+, ×30-200; F-, ×160-1040, Cl-, ×20-50; PO43-, ×700-2800; SO42-, ×30-150). In contrast, in the marine species H. crispae Na+, Cl- and SO42- are almost in ionic equilibrium with (brackish) salt water, while K+, Ca2+, Mg2+ and F- are only slightly concentrated (×2-10). An anion deficit of ~120 mEq 1-1 in M. tardigradum and H. crispae indicates the presence of unidentified ionic components in these species. Body fluid osmolality ranges from 361±49 mOsm kg-1 in R. coronifer to 961±43 mOsm kg-1 in H. crispae. Concentrations of most inorganic ions are largely identical between active and dehydrated groups of R. coronifer, suggesting that this tardigrade does not lose large quantities of inorganic ions during dehydration. The large osmotic and ionic gradients maintained by both limno-terrestrial and marine species are indicative of a powerful ion-retentive mechanism in Tardigrada. Moreover, our data indicate that cryptobiotic tardigrades contain a large fraction of unidentified organic osmolytes, the identification of which is expected to provide increased insight into the phenomenon of cryptobiosis.

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“…This stresses that digits apparently evolve easily among genera of arthrotardigrades, perhaps as an cE cirrus E, cl claw, cp cirrophore, ec external cirrus, ed external digit, ic internal cirrus, id internal digit, mc median cirrus, p4 leg pair IV sense organ, po pore, sc secondary clava, and sp scapus adaptation to the specific habitat, and their significance as phylogenetic characters above genus level is questionable. This would also explain why the family Halechiniscidae, that mainly was supported by the presence of digits, occurs as polyphyletic in analyses based on molecular sequence data (Jørgensen et al 2010). Abbreviations: cE cirrus E, cl claw, dpe dorsal pedunculus, ed external digit, go gonopore, id internal digit, le IV leg pair IV, lp III lateral processes 3, se seta, and sr seminal receptacle Regarding other characters, such as cirrus E and the shape of the cephalic plate, Neostygarctus resembles species of Stygarctidae, and as noted by Grimaldi de Zio et al (1982) Neostygarctus shares many similarities with Parastygarctus.…”

Section: Discussionmentioning

confidence: 89%

A new species of Neostygarctus (Arthrotardigrada) from the Condor Seamount in the Azores, Northeast Atlantic

et al. 2015

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The tardigrade fauna of Condor Seamount, west of the Azores, is relatively rich, and species from at least seven genera are represented. A new species of the rare marine genus Neostygarctus (Arthrotardigrada) was found at 206 m depth at the summit of the seamount. This is the first record of the genus from the Atlantic Ocean, and also the deepest record of the genus. The new species Neostygarctus oceanopolis sp. nov. is easily distinguished from the Mediterranean type species N. acanthophorus by the number of middorsal spines. N. acanthophorus has five dorsal spines, whereas the adult of N. oceanopolis sp. nov. has seven. The cave tardigrade from Japan, Neostygarctus lovedeluxe also has dorsal spines on all five segments, but only the cephalic and the caudal segments have a middorsal spine, while the three other trunk segments have two spines on each of the dorsal segmental body plates. For the first time, ventral plates are recorded for a species of Neostygarctus. A membranous coating of the all spines of the cephalic segment, the lateral processes of the first three trunk segments, and the spines of the fourth leg pair are unique for Neostygarctus.

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Molecular phylogeny of Arthrotardigrada (Tardigrada)

Cited by 88 publications

References 32 publications

The architecture of the nervous system of Echiniscus testudo (Echiniscoidea, Heterotardigrada)

The architecture of the nervous system of Echiniscus testudo (Echiniscoidea, Heterotardigrada)

Inorganic ion composition in Tardigrada: cryptobionts contain large fraction of unidentified organic solutes

A new species of Neostygarctus (Arthrotardigrada) from the Condor Seamount in the Azores, Northeast Atlantic

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