The importance of distinguishing pufferfish species (Lagocephalus spp.) in the Mediterranean Sea for ensuring public health: Evaluation of the genetic databases reliability in supporting species identification

Taxonomic identification of marine organisms is sometimes hindered by morphological similarities and utilization of wrong criteria. Therefore, the morphological approach often requires the support of molecular tools which usually rely on a comparison of DNA sequences available in free publicly-accessible databases. However, the process can be affected by wrongly deposited sequences which lead to specimens’ misidentification. This is the case of two toxic pufferfish species (Lagocephalus spadiceus and L. guentheri), both reported as Lessepsian invasive species, whose actual presence in the Mediterranean is debated within the scientific community. In this study, the reliability of the genetic databases GenBank and BOLD in supporting the discrimination of L. spadiceus and L. guentheri was assessed as it has been already debated in literature. Twenty Mediterranean specimens of L. guentheri were collected and morphologically identified. COI and cytb reference sequences were then produced and included in two separate analyses (one for each gene) together with corresponding online sequences of L. spadiceus and L. guentheri from all the available localities. A high percentage of sequences with non-valid taxonomic identification was observed, involving 32.5% of the COI and 43.7% of the cytb sequences from GenBank and 30% of the COI sequences from BOLD. The majority of sequences deposited under L. spadiceus, mostly of Mediterranean origin, were genetically confirmed to be misidentified L. guentheri. Outcomes highlighted two main shortcomings: i) a low taxonomic accuracy of official databases due to the presence of sequences attributed to wrong species; (ii) a significant underestimation of L. guentheri presence in the Mediterranean Sea. This study, therefore, underlines the necessity to improve the databases accuracy in term of deposited sequences reliability. In this specific case, accuracy is even more important, considering the involved toxic species and the potential concern for public health associated with their accidental entering in the seafood chain.