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

• Published in: Journal of zoological systematics and evolutionary research Vol. 53; no. 3; pp. 194 - 199
• Main Authors: Mejlon, Erica, De Wit, Pierre, Matamoros, Lisa, Erséus, Christer
• Format: Journal Article
• Language: English
• Published: Berlin Blackwell Publishing Ltd 01.08.2015; Hindawi Limited
• Subjects: 16S rDNA gene; 18S rDNA gene; Cytochrome c oxidase subunit I; Heterodrilus; phylogeny
• ISSN: 0947-5745; 1439-0469; 1439-0469
• DOI: 10.1111/jzs.12092

Heterodrilus is a group of marine Naididae, common worldwide in subtropical and tropical areas, and unique among the oligochaetes by their tridentate chaetae. The phylogenetic relationships within the group are assessed from the nuclear 18S rDNA gene, and the mitochondrial cytochrome c oxidase 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 Phallodrilinae. 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 subfamily. 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. The phylogenetic relationships within the exclusively marine clitellate genus Heterodrilus are assessed using molecular genetic data. Monophyly of Heterodrilus is corroborated and the studied sample of species suggest at least two major clades with different geographical distributions, in one of them 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 optimised on the phylogenetic tree, revealing a high degree of homoplasy.