Sharks of the genus Oxynotus (Chondrichthyes: Oxynotidae) are rare and poorly known benthic elasmobranchs, distributed in deep marine environments worldwide. Among them, the angular roughshark Oxynotus centrina (Linnaeus, 1758) is the only species of the genus reported in the Mediterranean Sea. Due to its biological traits, it is highly vulnerable to fishing pressures. Moreover, having experienced in the recent past a severe population decline in this area, it has been listed as Critically Endangered in the IUCN Red List. Through the analysis of two mitochondrial markers (COI and NADH2) widely used in elasmobranch studies, this work aims to investigate the intraspecific diversity and population connectivity of the species. Furthermore, the newly produced sequences were used to investigate the phylogenetic relationships among the species of the genus Oxynotus. To reach this scope, a total of 80 tissue samples were collected in Sardinian waters and from other Mediterranean areas, and the sequences newly produced here were compared with those already available in online databases. Preliminary results based on the concatenated dataset (COI+NADH2) indicate very low levels of genetic variability and a low number of haplotypes in O. centrina, suggesting a potential high connectivity among areas. Phylogenetic trees show a close relationship between the sailfin roughshark O. paradoxus Frade, 1929 and the prickly dogfish O. bruniensis (Ogilby, 1893), clearly separated from O. centrina. In addition, COI sequences suggest the occurrence of possible cryptic species and mislabelling/misidentification within the genus. Our results provide new genetic data for this poorly known species and lay the basis for future research that should encompass all the species included in the genus, presently lacking molecular characterization. Given the vulnerability of deep-sea species to environmental changes and human impacts, the implementation of baseline information is awaited to be provided for additional species, as it is essential for developing informed management and protection plans.
Pani, C., Di Crescenzo, S., Bellodi, A., Cariani, A., Catalano, G., Crobe, V., et al. (2025). In-Deep conservation: using genetic tools to protect a rare and threatened deep-sea shark.
In-Deep conservation: using genetic tools to protect a rare and threatened deep-sea shark
Alessia Cariani;Giusy Catalano;Valentina Crobe;
2025
Abstract
Sharks of the genus Oxynotus (Chondrichthyes: Oxynotidae) are rare and poorly known benthic elasmobranchs, distributed in deep marine environments worldwide. Among them, the angular roughshark Oxynotus centrina (Linnaeus, 1758) is the only species of the genus reported in the Mediterranean Sea. Due to its biological traits, it is highly vulnerable to fishing pressures. Moreover, having experienced in the recent past a severe population decline in this area, it has been listed as Critically Endangered in the IUCN Red List. Through the analysis of two mitochondrial markers (COI and NADH2) widely used in elasmobranch studies, this work aims to investigate the intraspecific diversity and population connectivity of the species. Furthermore, the newly produced sequences were used to investigate the phylogenetic relationships among the species of the genus Oxynotus. To reach this scope, a total of 80 tissue samples were collected in Sardinian waters and from other Mediterranean areas, and the sequences newly produced here were compared with those already available in online databases. Preliminary results based on the concatenated dataset (COI+NADH2) indicate very low levels of genetic variability and a low number of haplotypes in O. centrina, suggesting a potential high connectivity among areas. Phylogenetic trees show a close relationship between the sailfin roughshark O. paradoxus Frade, 1929 and the prickly dogfish O. bruniensis (Ogilby, 1893), clearly separated from O. centrina. In addition, COI sequences suggest the occurrence of possible cryptic species and mislabelling/misidentification within the genus. Our results provide new genetic data for this poorly known species and lay the basis for future research that should encompass all the species included in the genus, presently lacking molecular characterization. Given the vulnerability of deep-sea species to environmental changes and human impacts, the implementation of baseline information is awaited to be provided for additional species, as it is essential for developing informed management and protection plans.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
