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Phylogeny of Catenulida and support for Platyhelminthes
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Systematic Zoology.
2008 (English)In: Organisms Diversity & Evolution, ISSN 1439-6092, E-ISSN 1618-1077, Vol. 8, no 5, 378-387 p.Article in journal (Refereed) Published
Abstract [en]

Molecular studies have shown that Platyhelminthes is polyphyletic, placing Rhabditophora within Lophotrochozoa, whereas Acoela and Nemertodermatida are separate early bilaterian branches. However, there has been little evidence to support the position of Catenulida, a group that was traditionally classified within Platyhelminthes. In Ehlers' pioneering cladistic system of the Platyhelminthes they were placed as the earliest clade. Other morphologists have considered the Catenulida as an early bilaterian clade separate from Rhabditophora, a position that was supported in an early molecular study. Subsequent molecular phylogenetic studies, which placed Catenulida as the sister group of Rhabditophora with no or low branch support, included 18S rDNA data from only one or two catenulid species. The aims of the present study were (1) to test the putative sister-group relationship of Catenulida and Rhabditophora by improving the taxon sampling of molecular data spanning a larger part of catenulid taxonomic diversity and (2) to provide a phylogenetic framework for the systematization of Catenulida. Twelve catenulid species were sampled around Sweden. Both the 18S rDNA gene and the 28S rDNA gene were sequenced and analysed in a Metazoa-wide data set within parsimony and Bayesian frameworks. The results unambiguously support Catenulida as the sister group of Rhabditophora within Lophotrochozoa. Parsimony-based inferences about the common ancestor of Catenulida and Rhabditophora are presented. A definition of the name Platyhelminthes is suggested.

Place, publisher, year, edition, pages
2008. Vol. 8, no 5, 378-387 p.
Keyword [en]
Bilateria, Metazoa, Phylogeny, Ribosomal DNA
National Category
Biological Sciences
URN: urn:nbn:se:uu:diva-96768DOI: 10.1016/j.ode.2008.09.002ISI: 000262430000005OAI: oai:DiVA.org:uu-96768DiVA: diva2:171451
Available from: 2008-02-27 Created: 2008-02-27 Last updated: 2015-07-29Bibliographically approved
In thesis
1. Taxonomy and Phylogeny of Catenulida (Platyhelminthes) with Emphasis on the Swedish Fauna
Open this publication in new window or tab >>Taxonomy and Phylogeny of Catenulida (Platyhelminthes) with Emphasis on the Swedish Fauna
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis focuses on phylogenetic and taxonomic studies of Catenulida (Platyhelminthes). Catenulida is a group of microscopic free-living worms mainly found in freshwater habitats. The Swedish catenulid fauna was previously virtually unknown. The taxonomy of Catenulida is difficult because of the paucity of good morphological characters, which makes species identification extremely difficult.

Molecular phylogenies are inferred from DNA sequences. Based on two molecular markers, 18S rDNA and 28S rDNA, the phylogenetic position of Catenulida has now been well established as the sister group to the rest of the flatworms, Rhabditophora. Within Catenulida there is a basal split between two major clades: Retronectidae + Catenulidae and Stenostomidae. The hypothesis of the marine Retronectidae as the sister group of the limnic Catenulida is rejected.

Four molecular markers, 18S rDNA, 28S rDNA, ITS-5.8S and CO1, are used as a backbone to infer phylogeny and to generate hypotheses about species delimitation in Catenulida using parsimony jackknifing and Bayesian analysis. Anokkostenostomum comes out non-monophyletic, and Suomina nested within Catenula, so two new synonymies are proposed: Stenostomum Schmidt, 1848 (Anokkostenostomum Noreña et al. 2005) and Catenula Duges, 1832 (Suomina Marcus, 1945) are proposed.

A first report on Swedish freshwater Catenulida are given. A total of 13 species are reported from Sweden. Four of them, all belonging to the taxon Stenostomum are new to science: S. gotlandense n.sp.; S. handoelense n.sp.; S. heebuktense n.sp. and S. steveoi n.sp.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2008. 48 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 395
Biology, taxonomy, phylogeny, molecular phylogenies, cryptic species, micro-invertebrate, Biologi, Catenulida, Platyhelminthes
urn:nbn:se:uu:diva-8470 (URN)978-91-554-7097-5 (ISBN)
Public defence
2008-03-20, Zootissalen, Evolutionsmuseet, Villavägen 9, Uppsala, 10:00
Available from: 2008-02-27 Created: 2008-02-27Bibliographically approved

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