DNA-based phylogeny of the marine genus Heterodrilus (Annelida, Clitellata, Naididae) : Phylogeny of the clitellate genus Heterodrilus

• Heterodrilus is a group of marine Naididae, common worldwide in subtropical and tropical areas, and unique among the oligochaetes by their triden- tate chaetae. The phylogenetic relationships within the group are assessed from the nuclear 18S rDNA gene, and the mitochondrial cytochrome c oxi- dase subunit I (COI) and 16S rDNA genes. Sequence data were obtained from 16 Heterodrilus species and 13 out-group taxa; 48 sequences are new for this study. The data were analysed by Bayesian inference. Monophyly of the genus is corroborated by the resulting tree, with Heterodrilus ersei (a taxon representing a small group of species with aberrant male genitalia) proposed to be outside all other sampled species. Although earlier regarded as a member of the subfamily Rhyacodrilinae, both molecular and morphological data seem to support that Heterodrilus is closely related to Phallodril- inae. However, the results are not conclusive as to whether the genus is the sister group of, or a group nested inside, or separate from this latter sub- family. The studied sample of species suggests at least two major clades in Heterodrilus with different geographical distributions, in one of the clades, most species are from the Indo-West Pacific Ocean, while in the other, the majority are from the Western Atlantic Ocean. Morphological characters traditionally used in Heterodrilus taxonomy are optimized on the phylogenetic tree, revealing a high degree of homoplasy.

Ämnesord

NATURVETENSKAP  -- Biologi -- Evolutionsbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Evolutionary Biology (hsv//eng)

Nyckelord

16S rDNA gene

18S rDNA gene

Cytochrome c oxidase subunit I

Heterodrilus

phylogeny

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