The Gastropoda is one of the best studied classes of marine invertebrates. Yet, most species have been delimited based on morphology only. The application of DNA barcodes has shown to be greatly useful to help delimiting species. Therefore, sequences of the cytochrome c oxidase I gene from 108 specimens of 34 morpho-species were used to investigate the molecular diversity within the gastropods from the Portuguese coast. To the above dataset, we added available COI-5P sequences of taxonomically close species, in a total of 58 morpho-species examined. There was a good match between ours and sequences from independent studies, in public repositories. We found 32 concordant (91.4%) out of the 35 Barcode Index Numbers (BINs) generated from our sequences. The application of a ranking system to the barcodes yield over 70% with top taxonomic congruence, while 14.2% of the species barcodes had insufficient data. In the majority of the cases, there was a good concordance between morphological identification and DNA barcodes. Nonetheless, the discordance between morphological and molecular data is a reminder that even the comparatively well-known European marine gastropods can benefit from being probed using the DNA barcode approach. Discordant cases should be reviewed with more integrative studies.The present study was financed by FEDER through POFC-COMPETE, in the scope the project FCOMP-01-0124-FEDER-015429 funded by "Fundacao para a Ciencia e a Tecnologia" (FCT), Portugal. Work at CBMA was supported by FCT I.P. through the strategic funding UID/BIA/04050/2013. Sequencing at the Biodiversity Institute of Ontario was funded by the International Barcode of Life (iBOL), through the Canadian Centre for DNA Barcoding, from the Ontario Genomics Institute, Genome Canada, the Ontario Ministry of Research and Innovation, and the Natural Sciences and Engineering Research Council of Canada. Claudia Hollatz was supported by a CAPES Post-doctoral fellowship (Ministry of Education, Brazil), while Jorge Lobo was supported by a PhD fellowship (SFRH/BD/69750/2010) from FCT.info:eu-repo/semantics/publishedVersio
