Three, two, one! Revision of the long-bodied sphaerodorids (Sphaerodoridae, Annelida) and synonymization of Ephesiella, Ephesiopsis and Sphaerodorum

María Capa; Torkild Bakken; Karin Meißner; Arne Nygren

doi:10.7717/peerj.5783

Three, two, one! Revision of the long-bodied sphaerodorids (Sphaerodoridae, Annelida) and synonymization of Ephesiella, Ephesiopsis and Sphaerodorum

PeerJ. 2018 Oct 26:6:e5783. doi: 10.7717/peerj.5783. eCollection 2018.

Authors

María Capa^{1

2}, Torkild Bakken², Karin Meißner³, Arne Nygren^{4

5}

Affiliations

¹ Department of Biology, University of the Balearic Islands, Palma, Spain.
² NTNU University Museum, Norwegian University of Science and Technology, Trondheim, Norway.
³ Forschungsinstitut Senckenberg, Deutsches Zentrum für Marine Biodiversitätsforschung, Hamburg, Germany.
⁴ Sjöfartsmuseet Akvariet, Göteborg, Sweden.
⁵ Institutionen för marina vetenskaper, Göteborgs Universitet, Göteborg, Sweden.

Abstract

Background: Long-bodied sphaerodorids (Annelida, Sphaerodoridae) is the common name for members of the three closely and morphologically homogenous currently accepted genera of benthic marine bristle worms: Ephesiella, Ephesiopsis and Sphaerodorum. Members of this group share the presence of two dorsal and longitudinal rows of macrotubercles with terminal papillae, and two longitudinal rows of microtubercles, features that are unique among sphaerodorids. Genera are distinguished by the chaetae morphology. Members of Ephesiella are characterised by having compound chaetae (except, sometimes, simple chaetae in the first chaetigers), Sphaerodorum bear only simple chaetae, and Ephesiopsis have both compound and simple chaetae in all parapodia.

Methods: Mitochondrial (partial COI and 16S rDNA) and nuclear (partial 18S rDNA and 28S rDNA) sequence data of long-bodied sphaerodorids with compound and simple chaetae, and an outgroup of additional seven sphaerodorid species were analysed separately and in combination using Bayesian inference (BA), and Maximum Likelihood (ML) methods. Long-bodied sphaerodorids from around the world (including type specimens) were examined under a range of optical equipment in order to evaluate putative generic and specific diagnostic features, in addition to intraspecific variability.

Results: Phylogenetic analyses of mitochondrial and nuclear DNA sequences of specimens identified as Ephesiella and Sphaerodorum, based on chaeta morphology, were performed. Sphaerodorum and Ephesiella were recovered as paraphyletic and nested within each other. Revision of current nominal species diagnostic features are performed and discussed.

Discussion: Results contradict current generic definitions. Recovery of paraphyletic compound and simple chaetae clades urge the synonymization of these two genera of long-bodied sphaerodorids. Morphological data also suggest the synonymization of Ephesiopsis.

Keywords: Classification; Diagnostic features; Genera synonimization; Molecular phylogeny; Morphology; Polychaetes; Reciprocal monophyly; Systematics.

Grants and funding

Financial support was provided to María Capa by ForBio Research School, funded by the Research Council of Norway (project no. 248799) and the Norwegian Taxonomy Initiative (project no. 70184215) and by the Ramón y Cajal program (RYC-2016-20799) funded by the Spanish Ministerio de Economía, Industria y Competitividad, Agencia Estatal de Investigación, Comunidad Autónoma de las Islas Baleares and the European Social Fund. The Norwegian Taxonomy Initiative provided financial support to Arne Nygren (knr 49-13, pnr 70184228), to Torkild Bakken (knr 55-12, pnr 70184227); and by the Swedish Taxonomy Initiative (dnr 140/07 1.4 and 166/08 1.4) to Arne Nygren. Collections at Museo Nacional de Ciencias Naturales, Madrid, and Muséum National d’Histoire Naturelle, Paris, were visited thanks to the European Commission Taxonomic Initiative SYNTHESYS (ES-TAF-2839, ES-TAF-7033, and FR-TAF-2644). Publication fees were covered by Norwegian University of Science and Technology (NTNU) Publishing Fund to María Capa. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.