New deep-sea species of Xenoturbella and the position of Xenacoelomorpha

  title={New deep-sea species of Xenoturbella and the position of Xenacoelomorpha},
  author={Greg W. Rouse and Nerida G. Wilson and Jos{\'e} Ignacio Carvajal and Robert C. Vrijenhoek},
The discovery of four new Xenoturbella species from deep waters of the eastern Pacific Ocean is reported here. The genus and two nominal species were described from the west coast of Sweden, but their taxonomic placement remains unstable. Limited evidence placed Xenoturbella with molluscs, but the tissues can be contaminated with prey. They were then considered deuterostomes. Further taxon sampling and analysis have grouped Xenoturbella with acoelomorphs (=Xenacoelomorpha) as sister to all… 

Development of Xenoturbellida.

  • H. Nakano
  • Biology
    Results and problems in cell differentiation
  • 2019
Comparison with the other marine invertebrate larvae suggests that the morphologically simple swimming larvae described in Xenoturbella represent an ancestral larval type of all metazoans and bilaterians.

A New Species of Orthonectida That Parasitizes Xenoturbella bocki: Implications for Studies on Xenoturbella

This work regards this orthonectid found from the marine worm Xenoturbella bocki as a new species, Rhopalura xenoturbellae sp.

A bathypelagic ostracod Conchoecissa nigromaculatus sp. nov. (Myodocopa, Halocyprididae) from the South China Sea

In this species, mandibular coxal endite has no ventral finger process, maxilla has prominently large endites and has only two claws on the tip, the sixth limb has very simple endites, and this species has distinctive features not previously observed in the tribe Conchoeciini before, necessary to emend the diagnosis of this group.

Facultative chemosynthesis in a deep-sea anemone from hydrothermal vents in the Pescadero Basin, Gulf of California

Ottiactis pearseae represents the first member of Cnidaria described to date to have a physical and nutritional alliance with chemosynthetic bacteria and may play a role in symbiont sulfur cycling.

Hidden diversity of Acoelomorpha revealed through metabarcoding

Analysis of 18S rDNA metabarcoding data from three marine projects covering benthic and pelagic habitats worldwide shows that acoels have a greater richness in planktonic environments than previously described, and identifies a putative novel clade in the deep benthos that branches as sister group to the rest of Acoela, thus representing the earliest-branching acoel clade.

Mixotrophic chemosynthesis in a deep-sea anemone from hydrothermal vents in the Pescadero Basin, Gulf of California

The Cnidarian Ostiactis pearseae maintains a physical and nutritional alliance with chemosynthetic bacteria, consistent with what is known about other cnidarians and the SUP05 bacterial group, in that they both form dynamic relationships to succeed in nature.

Multiple paedomorphic lineages of soft-substrate burrowing invertebrates: parallels in the origin of Xenocratena and Xenoturbella

It is confirmed with phylogenetic data that a soft-substrata burrowing-related environment strongly favours paedomorphic evolution and suggested that the ancestral organisation of the enigmatic metazoan, Xenoturbella, might correspond to the larval part of a complex ancestral bilaterian ontogenetic cycle with sedentary/semi-sedentary adult stages and planula-like larval stages.

Phylogeny: A home for Xenoturbella

Four new deep-sea species of Xenoturbella are added from the eastern Pacific Ocean to the two already known from the Atlantic, and phylogenetic analysis aligns them at the base of the Protostomia or even as basal bilaterians.

Molecular approaches for studying the evolution of the Xenacoelomorpha

Gen visualisation protocols are developed and applied to investigate the expression patterns of genes commonly associated with ultrafiltration in Xenoturbella and the acoel Symsagittifera roscoffensis to shed light on the origin and homology of filtratory structures, which remain unclear.

Correction to: A new species of Xenoturbella from the western Pacific Ocean and the evolution of Xenoturbella

The authors describe the two xenoturbellids as a new species again in this correction article.



Feeding ecology of Xenoturbella bocki (phylum Xenoturbellida) revealed by genetic barcoding

Xenoturbella only contains molluscan DNA originating from bivalves living in the same environment, refuting former hypotheses of a bivalve relationship and suggesting that Xenoturblla feeds specifically onbivalve prey from multiple species, possibly in the form of eggs and larvae.

Xenoturbella is a deuterostome that eats molluscs

It is shown that the samples in these studies were contaminated by bivalve embryos eaten by Xenoturbella and that XenOTurbella is in fact a deuterostome related to hemichordates and echinoderms.

What is Xenoturbella?

  • H. Nakano
  • Biology, Environmental Science
    Zoological Letters
  • 2015
Although recent studies have uncovered many new and crucial facts regarding Xenoturbella, some fundamental biological information, such as phylogeny, complete life cycle, and genome, remain unsolved.

New light on the enigmatic Xenoturbella (phylum uncertain): ontogeny and phylogeny

  • O. Israelsson
  • Biology
    Proceedings of the Royal Society of London. Series B: Biological Sciences
  • 1999
The previously unknown embryology of Xenoturbella is reported here that unequivocally corroborates a bivalve relationship and thus once and for all dismisses the potential new phylum plesiomorphic phylum.

Acoelomorph flatworms are deuterostomes related to Xenoturbella

This phylogeny makes sense of the shared characteristics of Xenoturbellida and Acoelomorpha, and implies the loss of various deuterostome characters in the Xenobiology including coelomic cavities, through gut and gill slits.

The mitochondrial genome structure of Xenoturbella bocki (phylum Xenoturbellida) is ancestral within the deuterostomes

The mitochondrial genome of Xenoturbella bocki has a very conserved gene arrangement in the deuterostome group, strikingly similar to that of the hemichordates and the chordates, and thus to the ancestral deuterstome gene order.

Mitochondrial genomes of Galathealinum, Helobdella, and Platynereis: sequence and gene arrangement comparisons indicate that Pogonophora is not a phylum and Annelida and Arthropoda are not sister taxa.

Comparisons of relative gene arrangements and of the nucleotide and inferred amino acid sequences among these and other published taxa provide strong support for an annelid-mollusk clade that excludes arthropods, and for the inclusion of pogonophorans within Annelida, rather than giving them separate phylum status.

The Genome of the Ctenophore Mnemiopsis leidyi and Its Implications for Cell Type Evolution

The genome of the ctenophore the warty comb jelly or sea walnut, Mnemiopsis leidyi, is sequenced and it is concluded that c tenophores alone, not sponges or the clade consisting of both ctenphores and cnidarians, are the most basal extant animals.

The mitochondrial DNA of Xenoturbella bocki: genomic architecture and phylogenetic analysis

A second complete mitochondrial genome of this species is sequenced and phylogenetic analyses based on the amino acid sequences of all 13 mitochondrial protein-coding genes and on its gene order confirm the deuterostome relationship of Xenoturbella.

Deuterostome phylogeny reveals monophyletic chordates and the new phylum Xenoturbellida

To study the relationships among all deuterostome groups, an alignment of more than 35,000 homologous amino acids is assembled, including new data from a hemichordate, starfish and Xenoturbella and it is concluded that chordates are monophyletic.