<abstract xmlns="http://www.w3.org/1999/xhtml">

<p>In the nematode family Criconematidae, a taxonomy primarily based on cuticle characters has created classifications that are notoriously volatile. Molecular characters may lead to their stabilization. A phylogenetic tree of Criconematoidea was constructed using 166 new near full-length 18S rDNA sequences and 58 sequences from GenBank. Bayesian and maximum likelihood (ML) analyses produced trees with similar topologies. Major features include a strongly supported clade that includes Criconematidae and Hemicycliophoridae, excluding Paratylenchidae and Tylenchulidae. Another well-supported clade groups <italic>Criconema</italic>, <italic>Ogma</italic>, <italic>Crossonema</italic>, and <italic>Hemicriconemoides</italic> plus <italic>Xenocriconemella</italic>, combining nematodes with cuticular scales with those without scales at any life stage. <italic>Mesocriconema</italic>, <italic>Discocriconemella limitanea</italic>, <italic>Hemicaloosia</italic>, and <italic>Lobocriconema</italic> are recognized as monophyletic groups, but <italic>Criconemoides</italic> is paraphyletic. Both trees support an unexpected sister relationship between <italic>Bakernema</italic> and <italic>Hemicycliophora</italic>. The 18S rDNA dataset was insufficient for distinguishing genus boundaries between <italic>Criconema</italic>, <italic>Ogma</italic>, and <italic>Crossonema</italic>. The relationships depicted by the 18S rDNA phylogeny suggest that key morphological characters used in the classification of Criconematidae are not homologous.</p>
</abstract>

In the nematode family Criconematidae, a taxonomy primarily based on cuticle characters has created classifications that are notoriously volatile. Molecular characters may lead to their stabilization. A phylogenetic tree of Criconematoidea was constructed using 166 new near full-length 18S rDNA sequences and 58 sequences from GenBank. Bayesian and maximum likelihood (ML) analyses produced trees with similar topologies. Major features include a strongly supported clade that includes Criconematidae and Hemicycliophoridae, excluding Paratylenchidae and Tylenchulidae. Another well-supported clade groups Criconema, Ogma, Crossonema, and Hemicriconemoides plus Xenocriconemella, combining nematodes with cuticular scales with those without scales at any life stage. Mesocriconema, Discocriconemella limitanea, Hemicaloosia, and Lobocriconema are recognized as monophyletic groups, but Criconemoides is paraphyletic. Both trees support an unexpected sister relationship between Bakernema and Hemicycliophora. The 18S rDNA dataset was insufficient for distinguishing genus boundaries between Criconema, Ogma, and Crossonema. The relationships depicted by the 18S rDNA phylogeny suggest that key morphological characters used in the classification of Criconematidae are not homologous.

An 18S rDNA Perspective on the Classification of Criconematoidea

Journal of Nematology

This work is licensed under the Creative Commons Attribution 4.0 International License.

{"article-title":"An 18S rDNA Perspective on the Classification of Criconematoidea"}

In the nematode family Criconematidae, a taxonomy primarily based on cuticle characters has created classifications that are notoriously volatile. Molecular...

An 18S rDNA Perspective on the Classification of Criconematoidea

Published Online: Dec 03, 2017

Page range: 168 - 176

Received: Apr 20, 2017

DOI: https://doi.org/10.21307/jofnem-2017-069

Keywords
18S rDNA, classification, criconematidae, phylogeny, systematics, taxonomy.

© 2017 Thomas Powers et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

An 18S rDNA Perspective on the Classification of Criconematoidea

Published Online: Dec 03, 2017

Page range: 168 - 176

Received: Apr 20, 2017

DOI: https://doi.org/10.21307/jofnem-2017-069

Keywords18S rDNA, classification, criconematidae, phylogeny, systematics, taxonomy.

© 2017 Thomas Powers et al., published by Sciendo

This work is licensed under the Creative Commons Attribution 4.0 International License.

Keywords
18S rDNA, classification, criconematidae, phylogeny, systematics, taxonomy.