Journal of Molecular Evolution

, Volume 60, Issue 6, pp 706-715

First online:

First Sequenced Mitochondrial Genome from the Phylum Acanthocephala(Leptorhynchoides thecatus) and Its Phylogenetic Position Within Metazoa

  • Michelle L. SteinauerAffiliated withDepartment of Biology, University of New Mexico, MSC 03 2020, 1 Univesity of New Mexico Email author 
  • , Brent B. NickolAffiliated withSchool of Biological Sciences, University of Nebraska—Lincoln
  • , Richard BroughtonAffiliated withOklahoma Biological Survey and Department of Zoology, University of Oklahoma
  • , Guillermo OrtíAffiliated withSchool of Biological Sciences, University of Nebraska—Lincoln

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The complete sequence of the mitochondrial genome of Leptorhynchoides thecatus (Acanthocephala) was determined, and a phylogenetic analysis was carried out to determine its placement within Metazoa. The genome is circular, 13,888 bp, and contains at least 36 of the 37 genes typically found in animal mitochondrial genomes. The genes for the large and small ribosomal RNA subunits are shorter than those of most metazoans, and the structures of most of the tRNA genes are atypical. There are two significant noncoding regions (377 and 294 bp), which are the best candidates for a control region; however, these regions do not appear similar to any of the control regions of other animals studied to date. The amino acid and nucleotide sequences of the protein coding genes of L. thecatus and 25 other metazoan taxa were used in both maximum likelihood and maximum parsimony phylogenetic analyses. Results indicate that among taxa with available mitochondrial genome sequences, Platyhelminthes is the closest relative to L. thecatus, which together are the sister taxon of Nematoda; however, long branches and/or base composition bias could be responsible for this result. The monophyly of Ecdysozoa, molting organisms, was not supported by any of the analyses. This study represents the first mitochondrial genome of an acanthocephalan to be sequenced and will allow further studies of systematics, population genetics, and genome evolution.


Acanthocephala Leptorhynchoides thecatus Mitogenomics Metazoa Phylogeny Parasite