Phylogeny and Integrative Taxonomy of Tardigrada

  • Aslak Jørgensen
  • Reinhardt M. Kristensen
  • Nadja Møbjerg
Part of the Zoological Monographs book series (ZM, volume 2)


Tardigrade phylogeny is currently the object of intense investigations driven by an increasing amount of molecular data from a broad taxonomic range of tardigrades. New information obtained from these investigations plays a crucial role in establishing a reliable systematic framework of Tardigrada. Importantly, contemporary phylogenetic investigations readily incorporate and reinvestigate morphological characters and character systems. Most of these newer investigations are, however, primarily based on a few conservative nuclear genes (in addition to the mitochondrial COI). Emerging transcriptomic and genomic data sets provide promising new information for future phylogenetic studies.

Currently the traditional major taxa of Tardigrada are still accepted, with Eutardigrada constituted by Apochela and Parachela and Heterotardigrada by Echiniscoidea and Arthrotardigrada. However, the arthrotardigrades seem to be a paraphyletic assemblage of distantly related taxa. During the last decade, major rearrangements have occurred in the parachelan taxa Eohypsibioidea, Hypsibioidea, Isohypsibioidea and Macrobiotoidea. Likewise, progress has been made within Arthrotardigrada and Echiniscoidea, but stable phylogenies have yet to be reached within these major taxa.

At the species level, an integrative approach to taxonomy has recently been implemented. Thus, molecular methods in support of morphological investigations are used to facilitate the identification and characterization of different tardigrade species. Phylogenetic inference methods have been combined with DNA barcoding approaches, and the ITS2 secondary structure has been applied as a marker for taxonomy.

In this review we present the current knowledge of tardigrade phylogeny. We emphasise that major changes likely will occur within the phylogenies of arthrotardigrades and echiniscoideans as additional species and genes are sampled for use in molecular phylogenies. We also foresee that integrative approaches to species identification and description will become more widespread securing a firm basis for future investigations in tardigrade taxonomy and systematics.



We are grateful to scientific illustrator Stine Elle for her drawings of animals in the cladograms. Funding came from the Carlsberg Foundation and the Danish Council for Independent Research (grant no. DFF – 4090-00145).


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Copyright information

© Springer Nature Switzerland AG 2018

Authors and Affiliations

  • Aslak Jørgensen
    • 1
  • Reinhardt M. Kristensen
    • 2
  • Nadja Møbjerg
    • 1
  1. 1.Department of BiologyUniversity of CopenhagenCopenhagenDenmark
  2. 2.Natural History Museum, University of CopenhagenCopenhagenDenmark

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