title: Articulating "Archiannelids": Phylogenomics and Annelid Relationships, with Emphasis on Meiofaunal Taxa.
abstract: Annelid disparity has resulted in morphological-based classifications that disagree with phylogenies based on Sanger sequencing and phylogenomic analyses. However, the data used for the latter studies came from various sources and technologies, involved poorly occupied matrices and lacked key lineages. Here, we generated a new Illumina-based data set to address annelid relationships from a fresh perspective, independent from previously generated data and with nearly fully occupied matrices. Our sampling reflects the span of annelid diversity, including two symbiotic annelid groups (Myzostomida and Spinther) and five meiofaunal groups once referred to as part of Archiannelida (three from Protodrilida, plus Dinophilus and Polygordius). As well as the placement of these unusual annelids, we sought to address the overall phylogeny of Annelida, and provide a new perspective for naming of major clades. Our results largely corroborate the phylogenomic results of Weigert et al. (2014; Illuminating the base of the annelid tree using transcriptomics. Mol Biol Evol. 31:1391-1401), with "Magelona + Owenia" and Chaetopteridae forming a grade with respect to all other annelids. Echiura and Sipuncula are supported as being annelid groups, with Sipuncula closest to amphinomids as sister group to Sedentaria and Errantia. We recovered the three Protodrilida terminals as sister clade to Phyllodocida and Eunicida (=clade Aciculata). We therefore place Protodrilida as part of Errantia. Polygordius was found to be sister group to the scaleworm terminal and the possibility that it is a simplified scaleworm clade, as has been shown for the former family Pisionidae, is discussed. Our results were equivocal with respect to Dinophilus, Myzostomida, and Spinther possibly owing to confounding long-branch effects.
authors.affiliation: Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University Departamento de Genética e Biologia Evolutiva, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Sónia C S
authors.initials: SC
authors.lastname: Andrade
authors.affiliation: Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University Cardiff School of Biosciences, Cardiff University, BIOSI 1, Cardiff, United Kingdom.
authors.forename: Marta
authors.initials: M
authors.lastname: Novo
authors.affiliation: Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University Centro de Biologia Marinha, CEBIMar, University of São Paulo, São Sebastião, SP, Brazil.
authors.forename: Gisele Y
authors.initials: GY
authors.lastname: Kawauchi
authors.affiliation: Marine Biological Section, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Katrine
authors.initials: K
authors.lastname: Worsaae
authors.affiliation: Department of Biological and Environmental Sciences - Tjärnö, University of Gothenburg, Strömstad, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Pleijel
authors.affiliation: Museum of Comparative Zoology, Department of Organismic and Evolutionary Biology, Harvard University.
authors.forename: Gonzalo
authors.initials: G
authors.lastname: Giribet
authors.affiliation: Scripps Institution of Oceanography, University of California San Diego grouse@ucsd.edu.
authors.forename: Greg W
authors.initials: GW
authors.lastname: Rouse
mesh_terms: D000818:Animals; D000845:Annelida / Q000145:classification* / Q000235:genetics*; D019143:Evolution, Molecular; D010802:Phylogeny; D011077:Polychaeta / Q000145:classification / Q000235:genetics; D017422:Sequence Analysis, DNA
keywords: Aciculata; Errantia; Sedentaria; meiofauna; morphological diversification; phylogeny; polychaete; supermatrix