title: Evaluating the Utility of Single-Locus DNA Barcoding for the Identification of Ribbon Worms (Phylum Nemertea).
abstract: Whereas many nemerteans (ribbon worms; phylum Nemertea) can be identified from external characters if observed alive, many are still problematic. When it comes to preserved specimens (as in e.g. marine inventories), there is a particular need for specimen identifier alternatives. Here, we evaluate the utility of COI (cytochrome c oxidase subunit I) as a single-locus barcoding gene. We sequenced, data mined, and compared gene fragments of COI for 915 individuals representing 161 unique taxonomic labels for 71 genera, and subjected different constellations of these to both distance-based and character-based DNA barcoding approaches, as well as species delimitation analyses. We searched for the presence or absence of a barcoding gap at different taxonomic levels (phylum, subclass, family and genus) in an attempt to understand at what level a putative barcoding gap presents itself. This was performed both using the taxonomic labels as species predictors and using objectively inferred species boundaries recovered from our species delimitation analyses. Our data suggest that COI works as a species identifier for most groups within the phylum, but also that COI data are obscured by misidentifications in sequence databases. Further, our results suggest that the number of predicted species within the dataset is (in some cases substantially) higher than the number of unique taxonomic labels-this highlights the presence of several cryptic lineages within well-established taxa and underscores the urgency of an updated taxonomic backbone for the phylum.
authors.affiliation: Department of Marine Science, University of Gothenburg, Box 463, SE-405 30, Gothenburg, Sweden.
authors.forename: Per
authors.initials: P
authors.lastname: Sundberg
authors.affiliation: Department of Natural History, Royal Ontario Museum, 100 Queen's Park, Toronto, ON, M5S 2C6, Canada.|Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON, M5S 2B4, Canada.
authors.forename: Sebastian
authors.identifier: 0000-0003-3200-6207
authors.initials: S
authors.lastname: Kvist
authors.affiliation: Swedish Species Information Center, Swedish University of Agricultural Sciences, SE-75007, Uppsala, Sweden.
authors.forename: Malin
authors.initials: M
authors.lastname: Strand
mesh_terms: D000049:Acanthocephala / Q000235:genetics*; D000818:Animals; D004247:DNA / Q000235:genetics*; D058893:DNA Barcoding, Taxonomic / Q000379:methods*; D003576:Electron Transport Complex IV / Q000235:genetics; D056426:Genetic Loci; D016013:Likelihood Functions; D013045:Species Specificity
chemical_list: D004247:DNA; D003576:Electron Transport Complex IV