Journal of Molecular Evolution

, Volume 42, Issue 5, pp 552–559

18S rRNA suggests that Entoprocta are protostomes, unrelated to Ectoprocta


  • L. Y. Mackey
    • Department of Biological SciencesDuquesne University
  • B. Winnepenninckx
    • Departement BiochemieUniversiteit Antwerpen (UIA)
  • R. De Wachter
    • Koninklijk Belgisch Instituut voor Natuurwetenschappen
  • T. Backeljau
    • Koninklijk Belgisch Instituut voor Natuurwetenschappen
  • P. Emschermann
    • Institut für Biologie IIIAlbert-Ludwig-Universität-Freiburg
  • J. R. Garey
    • Department of Biological SciencesDuquesne University

DOI: 10.1007/BF02352285

Cite this article as:
Mackey, L.Y., Winnepenninckx, B., De Wachter, R. et al. J Mol Evol (1996) 42: 552. doi:10.1007/BF02352285


The Ento- and Ectoprocta are sometimes placed together in the Bryozoa, which have variously been regarded as proto- or deuterostomes. However, Entoprocta have also been allied to the pseudocoelomates, while Ectoprocta are often united with the Brachiopoda and Phoronida in the (super)phylum Lophophorata. Hence, the phylogenetic relationships of these taxa are still much debated. We determined complete 18S rRNA sequences of two entoprocts, an ectoproct, an inarticulate brachiopod, a phoronid, two annelids, and a platyhelminth. Phylogenetic analyses of these data show that (1) entoprocts and lophophorates have spiralian, protostomous affinities, (2) Ento- and Ectoprocta are not sister taxa, (3) phoronids and brachiopods form a monophyletic clade, and (4) neither Ectoprocta or Annelida appear to be monophyletic. Both deuterostomous and pseudocoelomate features may have arisen at least two times in evolutionary history. These results advocate a Spiralia-Radialia-based classification rather than one based on the Protostomia-Deuterostomia concept.

Key words

EctoproctaEntoproctaPhoronidaBrachiopodaLophophorata18S rRNAMolecular phylogenyOligochaetaHirudinidaPolychaeta





maximum parsimony

Copyright information

© Springer-Verlag New York Inc 1996