A DNA barcoding approach in the study of tardigrades

Cesari, Michele; Guidetti, Roberto; Rebecchi, Lorena; Giovannini, Ilaria; Bertolani, Roberto

doi:10.4081/jlimnol.2013.s1.e23

Cited by 22 publications

(17 citation statements)

References 54 publications

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“…A molecular approach is undoubtedly useful to identify and discriminate tardigrade species. Previous studies on some Macrobiotus taxa (Cesari et al ., ; Bertolani et al ., ,b; Cesari et al ., , ) identified a threshold in genetic difference between cox1 gene sequences that can help in discriminating two species: a p ‐distance and/or Kimura two‐parameter value higher than 3%. The analysed populations of Richtersius showed genetic distances often much higher than 3% amongst them (Table S2).…”

Section: Discussionmentioning

confidence: 99%

Morphological and molecular analyses onRichtersius(Eutardigrada) diversity reveal its new systematic position and lead to the establishment of a new genus and a new family within Macrobiotoidea

et al. 2016

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Important contributions have been made to the systematics of Eutardigrada in recent years, but these have also revealed that several taxa are polyphyletic and that cryptic species are present. To shed light on the taxonomy and systematic position of the genus Richtersius (Eutardigrada, Macrobiotoidea), six populations attributed to Richtersius coronifer were collected and analysed from morphological (light and scanning electron microscopy) and molecular (mitochondrial cytochrome oxidase subunit 1, 18S, 28S) points of view. In particular, a new morphometric index (claw common tract: length of the common tract of the claw/total claw length 9 100) and a new morphological character (stalk system) were introduced. Our integrative study was able to unveil the 'cryptic' species diversity within Richtersius, showing that the genus contains more than one evolutionary lineage. A morphological peculiarity in the animals of all lineages is the dimorphism in the morphology of the cuticle. Cuticular pores are present in the newborns and are lost with the first moult; this morphological change represents a novelty in the life cycle of eutardigrades. The phylogenetic analyses carried out on Richtersius populations and other Macrobiotoidea show that Richtersius is closely related to Macrobiotus islandicus, whereas Adorybiotus granulatus is more related to Richtersius and M. islandicus than to other members of the genus Macrobiotus (type genus of Macrobiotidae); therefore, the genus Macrobiotus and the family Macrobiotidae are not monophyletic. Based on these results, the new genus Diaforobiotus (for M. islandicus) and the new family Richtersiidae (composed of Richtersius, Diaforobiotus gen. nov., and Adorybiotus) are established.

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Section: Discussionmentioning

confidence: 99%

Morphological and molecular analyses onRichtersius(Eutardigrada) diversity reveal its new systematic position and lead to the establishment of a new genus and a new family within Macrobiotoidea

et al. 2016

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“…To date, few studies focusing on tardigrades have generated molecular and morphological data for the same specimens (but see Cesari et al ., 2011b, ). In all cases, no parts from the extracted specimen remain, as the small size of tardigrades makes it necessary to use the whole animal for DNA extraction, although in some cases the egg cases are left as vouchers (Cesari et al ., 2011a).…”

Section: Methodsmentioning

confidence: 99%

“…Photographing the specimens prior to DNA extraction becomes the only feasible solution to link genetic and anatomical data, as done by Cesari et al . (2011b, ). While many authors provide identifications of each individual used for DNA extraction, especially when multiple species coexist in a sample (Cesari et al ., ; Guil & Giribet, , ; Bertolani et al ., , 2011), photographs of specimens preceding DNA extraction become the only unequivocal link between DNA sequences and morphology.…”

Section: Methodsmentioning

confidence: 99%

Congruence between molecular phylogeny and cuticular design in Echiniscoidea (Tardigrada, Heterotardigrada)

et al. 2013

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Although morphological characters distinguishing echiniscid genera and species are well understood, the phylogenetic relationships of these taxa are not well established. We thus investigated the phylogeny of Echiniscidae, assessed the monophyly of Echiniscus, and explored the value of cuticular ornamentation as a phylogenetic character within Echiniscus. To do this, DNA was extracted from single individuals for multiple Echiniscus species, and 18S and 28S rRNA gene fragments were sequenced. Each specimen was photographed, and published in an open database prior to DNA extraction, to make morphological evidence available for future inquiries. An updated phylogeny of the class Heterotardigrada is provided, and conflict between the obtained molecular trees and the distribution of dorsal plates among echiniscid genera is highlighted. The monophyly of Echiniscus was corroborated by the data, with the recent genus Diploechiniscus inferred as its sister group, and Testechiniscus as the sister group of this assemblage. Three groups that closely correspond to specific types of cuticular design in Echiniscus have been found with a parsimony network constructed with 18S rRNA data.

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“…When possible, DNA was extracted from hologenophore specimens ( sensu Pleijel et al ., ), using the protocol described in Cesari et al . (, ). Fragments of the nuclear 18S (733–885 bp) and 28S (891–899 bp) genes were amplified following the methods described in Bertolani et al .…”

Section: Methodsmentioning

confidence: 99%

What if the claws are reduced? Morphological and molecular phylogenetic relationships of the genusHaplomacrobiotusMay, 1948 (Eutardigrada, Parachela)

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Eutardigrada systematics relies mainly on the morphology of the sclerified structures of the animals. In particular, the main division of Parachela into four superfamilies relies heavily upon claw morphology; however, this character, alone, may be either inadequate or useless for tardigrades with no claws, or when secondary claw branches are reduced or absent, as in the case of species belonging to the genus Haplomacrobiotus. This is a very uncommon genus, so far reported only in North America. The systematic position of this genus has been debated since its description, having first been placed in the family Macrobiotidae (Macrobiotoidea) and then in the family Calohypsibiidae (Hypsibioidea). Currently, the position of the supposedly related genus Hexapodibius is still debated, being attributed to Isohypsibiidae (Isohypsibioidea) or to Calohypsibiidae (Hypsibioidea), i.e. to two different superfamilies. The morphological (light and electron microscopy), chemical (X-ray spectroscopy), and molecular (18S and 28S genes) analyses of a population of Haplomacrobiotus utahensis Pilato & Beasley, 2005 from Snow Canyon State Park (Utah, USA) allowed us to validate the position of this genus within Isohypsibioidea. Our integrated findings placed Haplomacrobiotus in a close relationship with the genus Hexapodibius, and allowed us to erect the new family Hexapodibiidae, comprising the genera Hexapodibius, Parhexapodibius, Haplomacrobiotus, and Haplohexapodibius.

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A DNA barcoding approach in the study of tardigrades

Cited by 22 publications

References 54 publications

Morphological and molecular analyses onRichtersius(Eutardigrada) diversity reveal its new systematic position and lead to the establishment of a new genus and a new family within Macrobiotoidea

Morphological and molecular analyses onRichtersius(Eutardigrada) diversity reveal its new systematic position and lead to the establishment of a new genus and a new family within Macrobiotoidea

Congruence between molecular phylogeny and cuticular design in Echiniscoidea (Tardigrada, Heterotardigrada)

What if the claws are reduced? Morphological and molecular phylogenetic relationships of the genusHaplomacrobiotusMay, 1948 (Eutardigrada, Parachela)

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