Otekaikea, Tanaka and Fordyce, 2014

Tanaka, Y & Fordyce, R, 2015, A new Oligo-Miocene dolphin from New Zealand: Otekaikea huata expands diversity of the early Platanistoide, Palaeontologia Electronica (London, England) 9 (2), pp. 1-71 : 4-5

Genus OTEKAIKEA Tanaka and Fordyce, 2014

Type species. Prosqualodon marplesi Dickson, 1964 = Otekaikea marplesi ( Dickson, 1964) sensu Tanaka and Fordyce (2014) .

Included species. O. marplesi ( Dickson, 1964) and O. huata n. sp.

Diagnosis. Genus Otekaikea includes longirostral odontocetes with: condylobasal length around 790+ mm; procumbent tusks; presence of an intra-premaxillary foramina in each premaxilla; large and rounded carotid foramen; and a deep voluminous facial fossa. Otekaikea has the following synapomorphies: ventromedial edge of the internal opening of infraorbital foramen is formed by both the maxilla and palatine; both nasals have a point on the midline and gap with the premaxillae; nasals are relatively narrow; and accessory ossicle is fused on the periotic. Otekaikea differs from Waipatia in skull features that include: rostrum is relatively longer; premaxillary sac fossa is more elevated; posterolateral plate and posteromedial splint of the premaxilla are more distinct, with an infra-premaxillary foramen on the right or bilaterally; vertex is less symmetrical, with nasals subrhomboidal rather than transversely oval; ascending process of the maxilla is less-rounded; frontal on the vertex is anteroposteriorly shorter; postglenoid process is tapered rather than squared in lateral view; zygomatic process is more robust in ventral view; and paroccipital process has a medially-developed tongue-like articulation for the stylohyal. The teeth are near-homodont, and the cheekteeth mostly lack denticles; the mandibles have a fused symphysis. The periotic differs from Waipatia in that: anterior keel is less distinct; accessory ossicle is fused; a less-strongly projecting lateral tuberosity; a wider and more-circular internal acoustic meatus; posterior process is longer and subrectangular rather than elongate comma-shaped, and angled relative to the axis of the periotic from ventral or dorsal views. The posterior process of the bulla has less prominent sutures for the periotic, posterior meatal ridge, and post-tympanic process.

Otekaikea differs from Squalodontidae and Prosqualodon in lacking large robust heterodont cheekteeth. Differs from Notocetus , Squalodelphis , Huaridelphis , and Platanistidae in lacking: orbital fossae for extensions of pterygoid sinuses; thickened maxilla or elevated maxillary crest over orbit.

Otekaikea differs from other archaic Odontoceti including Xenorophidae , Simocetus , Agorophius , Patriocetus , Prosqualodon , Squalodontidae , and Waipatia , in the unique combination of apomorphies involving: broad dished face; nasals elevated, nodular, and subrhomboidal; frontals elevated; premaxillary sac fossae smooth-surfaced, without prominent premaxillary sulci developed posteriorly; premaxillae bifurcated posteriorly, each with an intra-premaxillary foramen at the junction between posterolateral plate and posteromedial splint, and elevated crests on the maxillae; periotic with long, slender, parallel-sided posterior process. Otekaikea differs from crown odontocetes other than Platanistoidea in lacking: the supracranial basin of Physeteriidae and Kogiidae ; an enlarged hamular fossa of Ziphiidae ; medially located aperture for the cochlear aqueduct of Eurhinodelphinidae ; and the orbital fossae for extensions of pterygoid sinuses, parabullary ridge of periotic, and saddle-shaped involucrum of the bulla of Delphinida.

Comment on higher taxonomy. Gray (1863) was the first to use the family-group name Platanistidae . The content of the family varied in later years, to include species of Platanista , and also Inia and Pontoporia , and finally Lipotes . Simpson (1945) used a new rank in the family group, Superfamily Platanistoidea , to encompass a single family, Platanistidae Gray, 1863 . He justified the superfamily rank in general terms with the comment “The number of genera and families [amongst Odontoceti ] has become so large that I have introduced superfamilies for the association of families that appear to be specially related” ( Simpson, 1945, p. 215). According to the International Code of Zoological Nomenclature (1999), Article 50.3, Gray (1863) remains the author. This authorship for Platanistoidea follows Fordyce and de Muizon (2001).