Figure 1

Phylogenetic relationships of the three octopod species analysed in this study and related octopodiformes. The Bayesian phylogenetic tree was based on the mitochondrial genes cytochrome oxidase subunit I and III and the nuclear genes rhodopsin, octopine dehydrogenase and 16S rDNA. Vampyroteuthis infernalis and Argonauta nodosa served as outgroup. Posterior probabilities were shown above nodes with stars marking values of 1.0. Colours denote the climatic origin. The opening of the Drake Passage ca. 29–32 million (Ma) years ago (position marked on tree was taken from [26]), denoting the isolation of Antarctic waters from warmer waters, preceded the diversification of the Antarctic genus Pareledone. Pareledone charcoti belongs to the endemic Southern Ocean octopod family Megaleledonidae and shares ancestry with Adelieledone polymorpha. This species inhabits the northern Antarctic Peninsula and the Scotia Arc island bridge connecting shallow South American waters with the Antarctic shelf, indicating an origin from temperate shallow waters [27]. Octopus pallidus and Eledone moschata belong to distinct families of non-polar shallow water octopods [28].