New Insights into the Molecular Phylogeny of Graneledone (Cephalopoda, Megaleledonidae) and Description of a New Species from the Southeastern Pacific Ocean

Deep-sea octopuses of the genus Graneledone currently include ten recognized species, yet their phylogenetic relationships remain insufficiently resolved. Here, we provide molecular phylogenetic analyses for eight species based on three mitochondrial markers (16S, COIII, COI) and formally describe a new species from the southeastern Pacific. Four specimens previously reported lacked evidence necessary for taxonomic validation; in this study, we examine eight additional individuals collected between 436 and 1482 m depth, generating new mitochondrial sequences and proposing an updated phylogenetic hypothesis for the genus. Species delimitation analyses strongly support the recognition of a new species. The newly described octopus is medium-sized, lacks an ink sac, and bears a single series of suckers on arms of similar length. Key diagnostic traits include 43–45 suckers on the hectocotylized (right third) arm, six to seven gill lamellae per demibranch, a VV-shaped funnel organ, and five to seven transverse folds on the ligula. Among all examined characters, the number of opposite suckers provides the most robust morphological distinction from congeners distributed across the Pacific, Atlantic, and Antarctic oceans. Our results highlight the value of integrative taxonomy in resolving species boundaries within Graneledone and reveal previously undocumented diversity in the deep Southeastern Pacific. Continued sampling and molecular analyses will be essential for identifying additional cryptic lineages and refining evolutionary hypotheses for this poorly explored deep-sea octopod lineage.