title: Mitochondrial genome data support the basal position of Acoelomorpha and the polyphyly of the Platyhelminthes.
abstract: We determined 9.7, 5.2, and 6.8 kb, respectively, of the mitochondrial genomes of the acoel Paratomella rubra, the nemertodermatid Nemertoderma westbladi, and the free-living rhabditophoran platyhelminth Microstomum lineare. The identified gene arrangements are unique among metazoans, including each other, sharing no more than one or two single gene boundaries with a few distantly related taxa. Phylogenetic analysis of the amino acid sequences inferred from the sequenced genes confirms that the acoelomorph flatworms (acoels+nemertodermatids) do not belong to the Platyhelminthes, but are, instead, the most basal extant bilaterian group. Therefore, the Platyhelminthes, as traditionally constituted, is a polyphyletic phylum.
authors.affiliation: Departament de Genètica, Universitat de Barcelona, Av. Diagonal, 645, 08028 Barcelona, Spain.
authors.forename: Iñaki
authors.initials: I
authors.lastname: Ruiz-Trillo
authors.forename: Marta
authors.initials: M
authors.lastname: Riutort
authors.forename: H Matthew
authors.initials: HM
authors.lastname: Fourcade
authors.forename: Jaume
authors.initials: J
authors.lastname: Baguñà
authors.forename: Jeffrey L
authors.initials: JL
authors.lastname: Boore
mesh_terms: D000818:Animals; D003062:Codon / Q000235:genetics; D004272:DNA, Mitochondrial / Q000235:genetics*; D023061:Gene Order / Q000235:genetics; D016678:Genome; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D010986:Platyhelminths / Q000145:classification* / Q000235:genetics; D012343:RNA, Transfer / Q000235:genetics; D017422:Sequence Analysis, DNA; D020539:Sequence Analysis, Protein; D014419:Turbellaria / Q000145:classification* / Q000235:genetics
chemical_list: D003062:Codon; D004272:DNA, Mitochondrial; D012343:RNA, Transfer