Fig. 2. Phylogenetic relationships of Southern Ocean endemic and deep-sea octopuses. Bayesian phylogenetic tree based on the results of the relaxed
phylogenetic analysis utilizing the seven genes: rhodopsin, pax-6, octopine dehydrogenase (ODH), 12S rDNA, 16S rDNA, cytochrome oxidase subunit
I (COI) and cytochrome oxidase subunit III (COIII) of 12 Antarctic octopus species, seven deep-sea octopus species and 15 outgroup taxa. The
topology is that from the posterior sample which has the maximum sum of posterior probabilities on its internal nodes. Each node in the tree is
labelled with its posterior probability, * indicates a posterior probability of 1.0. The divergence times correspond to the mean posterior estimate of
their age in millions of years. The genera Adelieledone (dark blue), Pareledone (blue), and Megaleledone (light blue) are endemic to Antarctic waters.
The deep-sea genera, Graneledone (red), Velodona (yellow), and Thaumeledone (orange) are a monophyletic group and are nested within the Antarctic
clade. The deep-sea clade was estimated to have originated around 33 millions years ago (Ma; 95% HPD interval 5–64 Ma). The three deep-sea
genera were estimated to have diverged from one another around 15 Ma (95% HPD interval 1–36 Ma). Depth ranges were taken from the literature
as follows except for P. turqueti and A. polymorpha (Allcock, unpublished data): A. piatkowski (Allcock et al., 2003a), Pareledone spp. except
P. turqueti (Allcock, 2005), M. setebos (Allcock et al., 2003b), G. antarctica (Voss, 1988; Vecchione et al., 2005), G. verrucosa (Allcock et al.,
2003c), G. boreopacifica and V. togata (Voss, 1988), T. peninsulae (Allcock et al., 2004; Strugnell et al., 2008), other Thaumeledone spp. (Allcock
et al., 2004).