Marine Mammals of the World: Systematics and Distribution (1998)


(page 121)
(…) Miller (1925) and Kellogg (1928) included the true porpoises in the family Delphinidae and did not even grant them subfamily status. However, Slijper (1936) and Fraser and Purves (1960) recognized them as a separate family, an arrangement that has been accepted by almost all subsequent authors. The phocoenids have traditionally been divided into three well-defined genera, Neophocaena, Phocoena, and Phocoenoides. Fraser (1937), followed by Ellerman and Morrison-Scott (1951) and Simpson (1945), included Phocoenoides in Phocoena, but the two genera are strongly differentiated. Phocoena dioptrica is remarkable for its conspicuous sexual dimorphism (Fraser 1968), and Barnes (1984b, 1985a) noted morphological and behavioral similarities between it and Phocoenoides dalli, so he erected the new genus Australophocoena for P. dioptrica, and recognized two subfamilies, Phocoeninae for Neophocaena and Phocoena, and Phocoenoidinae for Australophocoena and Phocoenoides. However, his arrangement was not corroborated by studies of the cytochrome b gene and the displacement loop of the mtDNA (Rosel et al. 1995). which instead indicated that Neophocoena phocoenoides is the most basal member of the family, while all the other species fall into an unresolved trichotomy between Phocoenoides dalli, Phocoena phocoena, and a southern clade consisting of P. dioptrica, P. sinus, and P. spinipinnis. (…)