Disentangling taxonomy within the Rhabditis (Pellioditis) marina (Nematoda, Rhadbitidae) species complex using molecular and morphological tools
Derycke, S.; Fonseca, G.; Vierstraete, A.; Vanfleteren, J.; Vincx, M.; Moens, T. (2007). Disentangling taxonomy within the Rhabditis (Pellioditis) marina (Nematoda, Rhadbitidae) species complex using molecular and morphological tools, in: Derycke, S. Patronen en processen in de genetische structuur van twee mariene nemarodentaxa Rhabditis (Pellioditis) marina and Halomonhystera disjuncta): een moleculaire, morfologische en experimentele benadering = Patterns and processes in the genetic structure of two marine nematode taxa (Rhabditis (Pellioditis) marina and Halomonhystera disjuncta): a molecular, morphology and experimental approach. pp. 113-136 In: Derycke, S. (2007). Patronen en processen in de genetische structuur van twee mariene nemarodentaxa Rhabditis (Pellioditis) marina and Halomonhystera disjuncta): een moleculaire, morfologische en experimentele benadering = Patterns and processes in the genetic structure of two marine nematode taxa (Rhabditis (Pellioditis) marina and Halomonhystera disjuncta): a molecular, morphology and experimental approach. PhD Thesis. Universiteit Gent. Faculteit Wetenschappen: Gent. X, 252 pp., more |  |
| Keywords | Classification > Taxonomy > Chemotaxonomy
Rhabditis (Pellioditis) marina (Bastian, 1865) Dougherty, 1955 [WoRMS]
Marine/Coastal |
| Abstract | Correct taxonomy is a prerequisite for biological research, but currently it is undergoing a serious crisis, resulting in the neglect of many highly diverse groups of organisms. In nematodes, species delimitation remains problematic due to their high morphological variability. Evolutionary approaches using DNA sequences can potentially overcome the problems caused by morphology, but they are also affected by flaws. A holistic approach with a combination of morphological and molecular methods can therefore produce a straightforward delimitation of species. The present study investigates the taxonomic status of some highly divergent mitochondrial haplotypes in the Rhabditis (Pellioditis) marina species complex by using a combination of molecular and morphological tools. We used concordance among phylogenetic trees of three molecular markers (COI, ITS, D2D3) to infer molecular lineages. Subsequently, morphometric data from nearly all lineages were analysed with multivariate techniques. The results showed that highly divergent genotypic clusters were accompanied by morphological differences, and we created a graphical polytomous key for future identifications. This study indisputably demonstrates that R. (P.) marina and R. (P.) mediterranea belong to a huge species complex and that biodiversity in free-living marine nematodes may seriously be underestimated. |
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