Phylum Tardigrada: an “individual” approach

Chester J. Sands, Sandra J. Mcinnes, Nigel J. Marley, William P. Goodall-Copestake, Peter Convey, Katrin Linse

Research output: Contribution to journalArticlepeer-review

134 Citations (Scopus)


Phylum Tardigrada consists of ∼1000 tiny, hardy metazoan species distributed throughout terrestrial, limno‐terrestrial and oceanic habitats. Their phylogenetic status has been debated, with current evidence placing them in the Ecdysozoa. Although there have been efforts to explore tardigrade phylogeny using both morphological and molecular data, limitations such as their few morphological characters and low genomic DNA concentrations have resulted in restricted taxonomic coverage. Using a protocol that allows us to identify and extract DNA from individuals, we have sequenced 18S rDNA from 343 tardigrades from across the globe. Using maximum parsimony and Bayesian analyses we have found support for dividing Order Parachela into three super‐families and further evidence that indicates the traditional taxonomic perspective of families in the class Eutardigrada are nonmonophyletic and require re‐working. It appears that conserved morphology within Tardigrada has resulted in conservative taxonomy as we have found cases of several discrete lineages grouped into single genera. Although this work substantially adds to the understanding of the evolution and taxonomy of the phylum, we highlight that inferences gained from this work are likely to be refined with the inclusion of further taxa—specifically representatives of the nine families yet to be sampled.
Original languageEnglish
Pages (from-to)861-871
Number of pages11
Issue number6
Early online date11 Jul 2008
Publication statusPublished - 1 Dec 2008


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