Home > Phylum selection > Nematoda > Systematic overview
Home How to cite this site Terms & conditions Disclaimer Contact Site tutorial / Help Links	Phylum Nematoda A systematic overview Traditionally, the Nematoda are divided into two large groups, the Adenophorea (or Aphasmidia) and the Secernentea (or Phasmidia). Recent phylogenetic analyses, however, suggest that the Adenophorea are paraphyletic with respect to the Secernentea. Several authors have therefore abandoned this subdivision, but I retain it for the time being until a comprehensive new framework for the Nematoda is established that also includes scientific names for all important groups. Similar to the high level groups, some of the traditional groups of lower rank are paraphyletic as well. In addition, some of the traditional groups underwent "fusion" or "splitting" events based on new phylogenetic insight. Some of the more significant changes are as follows: Members of the traditional group Trefusiida are now included in the Enoplida or in the group Triplonchida. The Mononchida, that were formerly included in the Dorylaimida, are now listed as a separate high ranking group. The groups Mermithida and Trichinellida, that formerly constitued the taxon Trichosyringida (or Trichocephalida) are now separate high ranking groups and the Trichosyringida is abandoned. From the Chromadorida in the traditional sense are now separated the Plectida and Desmodorida. However, the latter group appears to be non-monophyletic as well and this needs further research. The Monhysterida now include the formerly separate Desmoscolecida. In addition, the taxon Araeolaimida that has recently been excluded from the Monhysterida, appears to be non-monophyletic and is now included in Monhysterida again by some authors. In addition, the Monhysterida is paraphyletic in some analyses. The Secernentea are indeed a monophyletic group, but most recent analyses show that this group is synonymous with the traditional taxon Rhabditida, because Rhabditida are paraphyletic with respect to the remaining Secernentea. However, I keep the Rhabditida in its paraphyletic form until further analyses become available. The Strongylida appear to be within a basal Rhabditida group, but for the time being I keep it as a separate Ordo. The Aphelenchida and certain Rhabditida (e.g. Strongyloides) appear to be closely related to Tylenchida, but I retain here provisionally their traditional assignment. In summary, the phylogeny and taxonomy of the Nematoda is currently in a state of flux and requires substantial research before a satisfying solution can be reached. In the meantime I use here a conservative systematic framework that tries to keep traditional groups if their monophyly is not yet rejected, but also accepts new developments as long as they are well-founded. This page has been updated on April 15, 2011 This site is online since May 31, 2005 Copyright © by Nikola-Michael Prpic-Schäper. All rights reserved.	Related information: Main page: Nematoda References