Pinniped taxonomy: review of currently recognized species and subspecies, and evidence used for their description

1 Pinnipeds are charismatic but difficult to study, and taxonomy is poorly understood. An accurate taxonomic framework is essential for studies of biogeography, ecology and conservation. 2 Morphologic and genetic criteria used to recognize pinniped species and subspecies are evaluated individually for all taxa in the three families: Otariidae (sea lions and fur seals), Odobenidae (walruses) and Phocidae (seals). We advocate a pragmatic approach that, in general, follows the Evolutionary Species Concept and ‘diagnosability’ criterion for subspecies delimitations. 3 Of the 33 species, all have at least two lines of evidence to distinguish them, and of the 29 subspecies, 24 have at least one line of evidence, but five have inadequate support. We present a composite phylogeny for pinnipeds. 4 We propose that the genus Arctocephalus be limited to Arctocephalus pusillus, and we resurrect the name Arctophoca for at least six species and subspecies. 5 We recommend large sample sizes and broad, random sampling in further research on pinniped taxonomy. Taxa should be described based on robust statistical analysis, not by arbitrary division of characters, and molecular research should include analysis of mtDNA and nuDNA. 6 Finally, we offer suggestions for further taxonomic research (on hybridization in otariids, and to allow consideration of life history data in sampling) in an effort to improve our understanding of pinniped diversity. Even for taxa which are already protected, better understanding of their taxonomy can only enhance their conservation status and facilitate efforts to protect their habitats.