Order Cetacea, suborder Odontoceti, family Delphinidae. The genus Sousa has traditionally been united with Steno and Sotalia in the subfamily Steninae
(sometimes elevated to family level), based on morphologic similarities (Barnes et al. 1985). However, cytochrome b sequences do not support this grouping among Delphinidae (LeDuc et al. 1999) and instead suggest a relationship of Sousa with Delphinus, Lagenodelphis, Stenella, and Tursiops. Ross et al. (1995) proposed only 1 species under the name Sousa chinensis, with possibly 3 or
more subspecies, whereas Rice (1998) listed 3 species, S. teuszii, S. plumbea, and S. chinensis (Atlantic, Indian, and Pacific ocean humpback dolphins, respectively). Most recent authors recognize only 2 species: S. teuszii (Atlantic humpback dolphin) and S. chinensis (Indo-Pacific humpback dolphin).
