New insights into the systematics of North Atlantic Gaidropsarus (Gadiformes, Gadidae): flagging synonymies and hidden diversity

ABSTRACT

Gaidropsarus Rafinesque, 1810 is a genus of marine fishes, commonly known as rocklings, comprising 14 living species and showing a high ecological diversity from the intertidal zone to the deep sea. The systematics of this group has been controversial due to a general lack of representative specimens and the conservative morphology exhibited. A multidisciplinary approach combining the analysis of meristic data and the DNA barcode standard was applied in a species delimitation approach. Individuals representing eight valid and three unnamed species were collected, morphologically identified and archived in several museum collections. Comparison of DNA sequences shows complex results, furthering the idea of the difficult identification of specimens based on traditional taxonomy. DNA barcoding supports synonymies, like G. biscayensis–G. macrophthalmus and G. guttatus–G. mediterraneus, agreeing with the extensive overlaps observed in the meristic variables analysed and suggesting a reduction in the number of species. Genetic distances showed pairs of closely related species like G. granti–G. vulgaris and G. argentatus–G. ensis, the latter being only distinguished by one main distinctive character. Four deep-water specimens, morphologically classified only to the genus level, constituted three independent taxa apart from the ones present in this study and with no barcode matches in the repository databases. They could represent new records for the North Atlantic or unknown species of this genus. The results obtained show that more studies will be necessary to solve the systematics of this branch of the Gadiformes.

SUBJECT EDITOR:

• Christopher Kenaley

KEYWORDS:

• Barcoding
• COI
• meristics
• morphology
• rocklings
• taxonomy

Data accessibility

Photographs, DNA sequence data and other details of the reference data set of specimens employed in this investigation are available in the Barcode of Life Database in the project entitled ‘Molecular identification of Gaidropsarus fishes’, code GSRUS. Barcodes have also been deposited in GenBank under accession numbers KY250169–KY250315, KY370533 and KY370534.

Acknowledgements

This work partially fulfils the PhD degree requirements of DBG at the University of Vigo. The authors would like to thank the staff involved in the following research surveys of the ‘Instituto Español de Oceanografía’: INDEMARES-BANGAL 0811 and FLETÁN ÁRTICO 2015 (Project ECOPESLE). We also extend our thanks to the crews of the Research Vessels ‘Miguel Oliver’ and ‘Vizconde de Eza’ (Ministry of Agriculture, Food and Environment, Spain). Alberto Serrano is especially recognized. We are very grateful to Prof. Dr André Freiwald and Dr Lydia Beuck, from the Centre for Marine Environmental Sciences of the University of Bremen (Germany), for the deposit in the CFM-IEOMA of the Gaidropsarus specimen from Mauritania (SMS 2010 Survey) included in this study. Thanks are due to João Medeiros for his help in the collection of specimens from the Azores.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was funded through the research project ECOMARG 3, Ministry of Agriculture, Food and the Environment, Spain, and the EC LIFE 07/NAT/E/000732+ ‘Nature Biodiversity’ INDEMARES project. Oceanographic surveys were partially funded by the EU through the European Maritime and Fisheries Fund within the National Programme of data collection in the fisheries sector.