Morphology, Phylogeny and Distribution of Scaeurgus (Cephalopoda: Octopoda) in Southeast Pacific Seamounts

Résumé fourni par la source

Octopuses of the genus Scaeurgus inhabit upper bathyal benthic habitats and are composed of five recognized species. In this study, we conducted morphological and molecular phylogenetic analyses of two individuals of Scaeurgus and provided additional field observations of the genus in seamounts of the Nazca and Salas y Gómez ridges (southeast Pacific Ocean) over the last six years. Specifically, two specimens of Scaeurgus were collected at 234 m depth in 2019 during the EPIC oceanographic cruise onboard the R/V Mirai (JAMSTEC, Japan), and five other specimens were video recorded at depths between 210 and 340 m during three oceanographic expeditions in 2024 onboard the R/V Falkor (too) (Schmidt Ocean Institute). Both specimens collected during 2019 corresponded to medium-sized females (18 and 38 mm mantle length). Each arm presented 108–132 biserial suckers, nine to ten lamellae per demibranch, and a W-shaped funnel organ. Morphological traits evidenced a closer resemblance of these specimens to S. patagiatus from the NW Pacific; however, phylogenetic evidence did not clearly differentiate them from S. unicirrhus from the Atlantic and the Mediterranean. Although molecular evidence supports the hypothesis of the monophyly of Scaeurgus, further morphological and genetic analysis are needed to delimit and validate the different species proposed along the global distribution of the genus.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.