Unveiling hidden marine biodiversity in the southern Atlantic Moroccan ecosystem: integrating DNA barcoding and morphological reassessment

Marine biodiversity provides vital ecosystem services but faces multiple threats, leading to global declines and increasing concern. Effective conservation of marine biodiversity requires comprehensive knowledge of species and accurate taxonomic identification, which remain challenging. DNA barcoding offers a reliable method for species identification. Focusing on the Southern Atlantic Moroccan ecosystem, this study aims to link DNA barcodes to species, investigate cryptic diversity and provide an updated marine species checklist. A total of 145 specimens from 85 species were collected and barcoded, producing 72 unique BINs in BOLD. Most sequences exhibited over 97.8% similarity with existing data, while nine sequences formed three new BINs. Twenty-three species displayed 2-12 BINs, indicating potential cryptic diversity or misidentifications. Additionally, sequences were used for Discriminant Analysis of Principal Components and Neighbor-joining analyses, thereby improving understanding of species boundaries. A morphological reassessment of the specimens was performed when discordances between BIN assignments and species names were observed. This study contributed to updating Morocco's marine checklist, demonstrated high success in species-level discrimination by combining genetic and morphological reassessments, and revealed potential cryptic diversity that warrants further investigation. Continued research is essential to monitor and conserve the Moroccan marine biodiversity amid global environmental changes.