Arktocara, Alexandra T. Boersma & Nicholas D. Pyenson, 2016

Alexandra T. Boersma & Nicholas D. Pyenson, 2016, Arktocara yakataga, a new fossil odontocete (Mammalia, Cetacea) from the Oligocene of Alaska and the antiquity of Platanistoidea, Peerj 2321, pp. 1-41 : 7-8

Arktocara , gen. nov.

LSID: urn:lsid:zoobank.org:act:EE11B95B­8338­496B­

97F4­1673ED90E709

Definitions. Crown group Platanista refers to the crown clade arising from the last common ancestor of all lineages descending from Platanista , including two subspecies of Platanista gangetica (P. g. gangetica ( Lebeck, 1801) and P. g. minor Owen, 1853), as recognized by The Society for Marine Mammology’ Committee on Taxonomy (2015).

Platanistoidea is a converted clade name for a clade that includes Platanista gangetica and fossil taxa that support familial level taxonomic concepts such as: Allodelphis pratti; Squalodelphis fabianii Dal Piaz, 1917; and Waipatia maerewhenua. We do not formally recognize node­based versions of Squalodelphinidae and Waipatiidae at this time (except for in the Diagnosis section) because these familial level groupings are not the explicit focus of this study, and we defer to future work that can better substantiate their taxonomic scope and better test their monophyly (see, for example, Tanaka & Fordyce, 2014; Tanaka & Fordyce, 2015a). This node­based converted clade of Platanistoidea corresponds to the Fordyce (1994) ’s concept of Platanistoidea, but differs from Muizon (1987), and Muizon (1991)’s concept, in its exclusion of Squalodontidae . Following Lambert, Bianucci & Urbina (2014), we exclude Squalodontidae and stem Platanistoidea, such as Prosqualodon davidis Flynn, 1923, and Papahu taitapu Aguirre­FernAEndez & Fordyce, 2014, from our node­based concept of Platanistoidea. Our concept is more inclusive than Geisler et al. (2011) ’s Platanistoidea, which included only Platanista, Zarhachis and Squalodelphis , while excluding Waipatia to outside of crown Odontoceti. Moreover, our concept of Platanistoidea shares very little with Simpson (1945) ’s articulation, which included all ‘river dolphin’ lineages, including Inia, Pontoporia, and Lipotes. Subjective synonymies of the converted clade name of Platanistoidea include, among others: Platanistoidea Fordyce, 1994; Platanistoidea Barnes, 2006; Platanistoidea Tanaka & Fordyce, 2014; Platanistoidea Tanaka & Fordyce, 2015a; Platanistoidea Kimura & Barnes, 2016.

Here, we also propose the converted clade name Platanistidae as a node­based clade defined by Platanista, Zarhachis and Pomatodelphis. This node­based converted clade of Platanistidae corresponds to the most recent concepts of the familial level grouping of closest fossil relatives of Platanista , such as Platanistidae Barnes, 2006 ; Platanistidae Barnes, Kimura & Godfrey, 2010 ; Platanistidae Geisler et al., 2011 ; and Platanistidae Bianucci et al., 2013 .

Lastly, Allodelphinidae is the converted clade name for the clade that includes the following fossil odontocete genera: Allodelphis, Arktocara, Goedertius, Ninjadelphis, and Zarhinocetus. Subjective synonymies of the converted clade name include: Allodelphinidae Barnes, 2006 ; Allodelphinidae Lambert, Muizon & Bianucci, 2015 ; Allodelphinidae Kimura & Barnes, 2016 . All previous studies have indicated that Allodelphinidae belongs as a sub­clade within a node­based Platanistoidea.

Type and only included species: Arktocara yakataga, sp. nov.

Etymology. The name Arktocara derives from the combination of arktos from Greek and cara from Latin, which together signify ‘‘the face of the North.’’ The only preserved material of the type specimen, USNM 214830 consists of the cranium, or its face, and its type locality is the furthest north that a platanistoid has ever been found.

Age. Same as that of the species.

Diagnosis. Same as that of the species.