Molecular phylogenetic reconstruction and taxonomic investigation of eelpouts (Cottoidei: Zoarcales) based on Co-1 and Cyt-b mitochondrial genes

Abstract

The infraorder Zoarcales (Cottoidei), or eelpouts, includes about 400 species of coldwater fishes concentrated mainly in the North Pacific. To date, the molecular phylogenetic methods in combination with morphological data have significantly contributed to understanding the taxonomic composition of this group and made it possible to confirm/refute validity of some families of obscure origin. In spite of the growing amount of new data on taxonomy and evolution of eelpouts, a consideration of the original and independent data is obviously needed to verify the existing knowledge of this taxon. In this study, which is based on concatenated matrix of Co-1 and Cyt-b mitochondrial genes, as well as relying on the samples from seven families and 45 species of eelpouts, we have reconstructed the phylogeny, which is generally consistent with previous inferences. Despite the resolution of the original data matrix is low, we have demonstrated the monophyletic origin of the families Zoarcidae and Anarhichadidae, as well as Neozoarcidae, previously related to Stichaeidae and recently revised Eulophiidae. The polyphyletic patterns amongst some subfamilies in Stichaeidae have been confirmed, whereas Opisthocentrinae and Pholidae seem to constitute a valid family-level taxon. Our results provide new opportunities with respect to taxonomic relationships in the complex and diverse group of eelpouts , whose part in the tree of life is not covered by recently flourishing multilocus phylogeny of teleost fishes. In light of the data obtained, the necessity of more unified and reproducible approaches to resolve the issues of evolution and taxonomy of such a complex group as Zoarcales becomes more evident.

Keywords:

• Co-1
• Cyt-b
• eelpouts
• mitochondrial genes
• phylogeny
• taxonomy
• Zoarcales

Acknowledgements

The authors are very thankful to I.A. Barsegova and E.P. Shvetsov for their proofreading of the manuscript.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.

Funding information

The authors gratefully acknowledge the financial support provided by the Russian Science Foundation (project no. 14-50-00034 connected with the section of molecular phylogenetics) and in part by the Russian Foundation for Basic Research (project no. 14-04-00758, connected with genetic differentiation between species). Also, funding was provided in part by the Far Eastern Branch of the Russian Academy of Sciences in the framework of the Federal Program of Base Research (projects no. 15-I-6-014 о, 15-II-6-075).