Taxonomy and Phylogeny
The taxonomy of ringed seal has been much debated and revised in the literature. Due to its wide range, as many as ten subspecies have been described. Currently, five distinct subspecies are recognized: P. h. hispida in the Arctic Ocean and Bering Sea, P. h. ochotensis in the Sea of Okhotsk, P. h. saimensis in Lake Saimaa in Finland, P. h. ladogensis in nearby Lake Ladoga in Russia and P.h. botnica in the Gulf of Bothnia. The ringed seal is most closely related to the Caspian seal (P. caspica) and Baikal seal (P. sibirica), all of which share similar small sizes, features of skull morphology and affinity for ice.
The closest phylogenetic relatives to the ringed seal are the grey seal (Halichoerus grypus) and the species in the Phoca genus (harbor seal and largha seal), to which the ringed seals were formerly attributed. Together with the remaining northern latitude ice seals (ribbon seal, bearded seal, harp seal and hooded seal), these seals constitute the subfamily Phocinae.
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