Paralarval and juvenile stages as a proxy for cephalopod diversity in the juan fernández and desventuradas ecoregion, southeast pacific ocean

Southeast Pacific (SEP) oceanic islands are characterized by their extreme isolation and high degree of endemism. To date, most research has focused on species composition and distributions, with little information available on early life stages. In this study, we provide new records of early life stages of cephalopods based on planktonic collections carried out during October and November 2016 around three oceanic islands: San Félix, San Ambrosio (Desventuradas Islands; 26.3°S, 79.8°W), and Alejandro Selkirk (Juan Fernández Archipelago; 33.7°S, 80.7°W), which are part of the Nazca-Desventuradas Marine Park, the largest marine park in the Americas. Twenty-four paralarvae and juveniles were obtained and identified based on morphological characteristics [i.e., mantle length (ML), chromatophore patterns, number and shape of suckers on arms and tentacles] and DNA barcoding [i.e., mitochondrial Cytochrome c Oxidase subunit I (COI) sequences]. Six families were recorded, including Brachioteuthidae, Onychoteuthidae, Tremoctopodidae, Octopodidae, Octopoteuthidae, and Lycoteuthidae. Most individuals (92%) corresponded to larger stages of 4-12 mm ML (Brachioteuthidae, Onychoteuthidae, Tremoctopodidae, and Lycoteuthidae), and 8% were newly hatched paralarvae of around 1 mm ML (Octopodidae and Octopoteuthidae). The DNA barcoding approach validated the identity of Brachioteuthis sp., Onykia aff. robsoni, Octopus mimus, and Tremoctopus sp., with two specific identities (Octopoteuthidae and Lycoteuthis sp.) remaining to be evaluated. These records provide new information on cephalopod diversity and distribution around SEP islands, adding to the current knowledge about zoogeographic patterns of this group and evidencing their potential relationships with continental or nearby habitats.