Biodiversity and vertical distribution of pelagic cephalopods in the Western Tropical Atlantic

We propose an integrative analysis of the diversity and distribution of pelagic cephalopods collected in the Western Tropical Atlantic (WTA), encompassing the Amazon River mouth, oceanic islands, and seamounts. A total of 1,270 specimens were collected from surface waters down to 1,500 m depth, representing 33 species and two taxa identified at the genus level, distributed among 31 genera, 19 families, and six orders. The known distribution ranges of at least ten species are extended, and new occurrence records are provided for several rare species. The assemblage was dominated by Abralia veranyi, Japetella diaphana, Enoploteuthis anapsis , and Vampyroteuthis infernalis , which accounted for most of the abundance and biomass, and whose ecological roles are further discussed. Comparisons with data from other oceanic regions indicate that tropical cephalopod assemblages exhibit lower species richness than those from temperate zones, a pattern that contrasts with trends observed in other pelagic taxa occupying similar environments. Overall, this study provides the first comprehensive assessment of pelagic cephalopod diversity in the WTA, establishing an essential ecological baseline for this poorly known deep-pelagic fauna and supporting future biodiversity monitoring and management efforts in the region. • Comprehensive survey of pelagic cephalopods in the Western Tropical Atlantic. • The 1,270 specimens revealed 35 species across 31 genera and six orders. • Four species dominated abundance and biomass. • Distributions of at least ten species were extended. • Comparative analysis indicates reduced diversity in tropical regions.