Historically significant late Oligocene dolphin Microcetus hectori Benham 1935: a new species of Waipatia (Platanistoidea)

The late Oligocene dolphin Microcetus hectori Benham 1935 (Otekaike Limestone, Duntroonian, around 25.2 million years ago) is documented, involving redescription of the teeth, and new description of the formerly undescribed skull. A separate recent phylogenetic analysis that included skull features indicates that M. hectori belongs in the genus Waipatia, rather than with Microcetus ambiguus. Waipatia hectori is readily distinguished from the older Waipatia maerewhenua by features that include: more robust zygomatic process of the squamosal; larger foramen spinosum; long and slender postorbital process; more inflated cheek-teeth. The two species of Waipatia form a basal clade in the Platanistoidea, elucidating the relationships of the hitherto monotypic late Oligocene genus Waipatia.