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Journal of Molecular Evolution

, Volume 50, Issue 6, pp 532–540 | Cite as

Phylogenetic Relationships of Acanthocephala Based on Analysis of 18S Ribosomal RNA Gene Sequences

  • Martín  García-Varela
  • Gerardo  Pérez-Ponce de León
  • Patricia  de la Torre
  • Michael P.  Cummings
  • S.S.S.  Sarma
  • Juan P.  Laclette

Abstract.

Acanthocephala (thorny-headed worms) is a phylum of endoparasites of vertebrates and arthropods, included among the most phylogenetically basal tripoblastic pseudocoelomates. The phylum is divided into three classes: Archiacanthocephala, Palaeacanthocephala, and Eoacanthocephala. These classes are distinguished by morphological characters such as location of lacunar canals, persistence of ligament sacs in females, number and type of cement glands in males, number and size of proboscis hooks, host taxonomy, and ecology. To understand better the phylogenetic relationships within Acanthocephala, and between Acanthocephala and Rotifera, we sequenced the nearly complete 18S rRNA genes of nine species from the three classes of Acanthocephala and four species of Rotifera from the classes Bdelloidea and Monogononta. Phylogenetic relationships were inferred by maximum-likelihood analyses of these new sequences and others previously determined. The analyses showed that Acanthocephala is the sister group to a clade including Eoacanthocephala and Palaeacanthocephala. Archiacanthocephala exhibited a slower rate of evolution at the nucleotide level, as evidenced by shorter branch lengths for the group. We found statistically significant support for the monophyly of Rotifera, represented in our analysis by species from the clade Eurotatoria, which includes the classes Bdelloidea and Monogononta. Eurotatoria also appears as the sister group to Acanthocephala.

Key words: Acanthocephala — Archiacanthocephala — Eoacanthocephala — Palaeacanthocephala — Rotifera — Eurotatoria — Bdelloidea — Monogononta — 18S rRNA — Phylogeny 

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Copyright information

© Springer-Verlag New York Inc. 2000

Authors and Affiliations

  • Martín  García-Varela
    • 1
  • Gerardo  Pérez-Ponce de León
    • 2
  • Patricia  de la Torre
    • 1
  • Michael P.  Cummings
    • 3
  • S.S.S.  Sarma
    • 4
  • Juan P.  Laclette
    • 1
  1. 1.Department of Immunology, Instituto de Investigaciones Biomédicas UNAM, A.P. 70228, 04510 México D.F., MéxicoMX
  2. 2.Department of Zoology, Instituto de Biología, UNAM, A.P. 70228, 04510 México D.F., MéxicoMX
  3. 3.The Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543-1015, USAUS
  4. 4.Carrera de Biología, Escuela Nacional de Estudios Profesionales, UNAM, A.P. 316, 54090 Edo. de México, MéxicoMX

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