Novelty in Phylogeny of Gastrotricha: Evidence from 18S rRNA Gene

Annarita Wirz, Sandra Pucciarelli, Cristina Miceli, Paolo Tongiorgi, Maria Balsamo

Research output: Contribution to journalArticlepeer-review


Gastrotricha form a phylum which is crucial for defining the origin of pseudocoelomates, in that they share a number of characters with Rotifera and Nematoda but also with acoelomates, and even the evolutionary relationships within the phylum are anything but defined. For this reason the first extensive molecular data on Gastrotricha from the 18S rRNA sequences of both orders have been obtained and analyzed. Sequence analyses show that the phylum Gastrotricha is strictly monophyletic along an evolutionary line quite distinct from that of both Rotifera and Nematoda. A new view of the evolutionary history of the phylum Gastrotricha is put forward, in which Chaetonotida, and not Macrodasyida, are the most primitive forms of the group, contrary to the commonly held view. A polyphyletic origin of aschelminthes is supported, and the misleading term pseudocoelomates should be discarded.

Original languageEnglish
Pages (from-to)314-318
Number of pages5
JournalMolecular Phylogenetics and Evolution
Issue number2
Publication statusPublished - Nov 1999


  • Molecular phylogeny; ribosomal RNA; Gastrotricha; Aschelminthes

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • Molecular Biology


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