A taxogenomics approach uncovers a new genus in the phylum Placozoa

@article{Eitel2017ATA,
  title={A taxogenomics approach uncovers a new genus in the phylum Placozoa},
  author={Michael Eitel and Warren R. Francis and Hans-J{\"u}rgen Osigus and Stefan Krebs and Sergio Vargas and Helmut Blum and Gray A. Williams and Bernd Schierwater and Gert W{\"o}rheide},
  journal={bioRxiv},
  year={2017}
}
The Placozoa [1] is a monotypic phylum of non-bilaterian marine animals. Its only species, Trichoplax adhaerens, was described in 1883 [2], Despite the worldwide distribution of placozoans [3–6], morphological differences are lacking among isolates from different geographic areas and, consequently, no other species in this phylum has been described and accepted for more than 130 years. However, recent single-gene studies on the genetic diversity of this “species” have revealed deeply divergent… 

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INTRODUCTION

References

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Global Diversity of the Placozoa

TLDR
There is great potential and need to erect new taxa and to establish a firm system for this taxonomic tabula rasa within this phylum.

The Trichoplax genome and the nature of placozoans

TLDR
Despite the apparent cellular and organismal simplicity of Trichoplax, its genome encodes a rich array of transcription factor and signalling pathway genes that are typically associated with diverse cell types and developmental processes in eumetazoans, motivating further searches for cryptic cellular complexity and/or as yet unobserved life history stages.

The phylogeography of the Placozoa suggests a taxon‐rich phylum in tropical and subtropical waters

TLDR
Worldwide sampling and sequencing of the mitochondrial large ribosomal subunit (16S) reveals a cosmopolitan distribution in tropical and subtropical waters of genetically different clades and identifies several euryoecious haplotypes with a cosmopolitic distribution as well as some stenoecioushaplotypes with an endemic distribution.

Placozoa are not derived cnidarians: evidence from molecular morphology.

TLDR
The new molecular morphological characters provide compelling evidence that Trichoplax is not a derived (medusozoan) cnidarian, and it was found that the mitochondrial genome in Cubozoa consists of four linear molecules instead of a single circular molecule or two linear molecules, suggesting that the cubozoans may represent the most derived cNidarian group.

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TLDR
Changes in gene content are consistent with the view that ctenophores and sponges are the earliest-branching metazoan lineages and provide additional support for the proposed clade of Placozoa/Cnidaria/Bilateria.

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TLDR
The present study determined the mitochondrial genome sequence of a placozoan collected on the coast of Shirahama, Wakayama, Honshu, Japan, and compared it with those of Trichoplax adhaerens from the Red Sea and of three strains from the Caribbean Sea, finding that the ‘Shirahama’ strain most likely represents the H15 lineage.

Delineation of Taxonomic Species within Complex of Species: Aeromonas media and Related Species as a Test Case

TLDR
Genetic and genomic data analysis provided a more comprehensive knowledge of the cladogenesis determinants at the root and inside A. media species complex among aeromonads, and suggested that a third clade is a distinct genomospecies.

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TLDR
The analytical pipeline outlined here combines probabilistic phylogenomic inference with methods for evaluating data quality, model adequacy, and assessing systematic error, and thus is likely to help resolve similarly difficult internodes in the tree of life.

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TLDR
This study assembled the richest taxon sampling of Enterobacteriaceae to date and analyzed both nucleic and amino acid data sets using several probabilistic methods to address the monophyly versus polyphyly of enterobacterial symbionts by exploring a multigene matrix within a complex phylogenetic framework.

Placozoa – no longer a phylum of one

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