Gw mau tau Sebelumnya dikelompokkan dalam Cetotherium dari Cetotherium

The following species were originally described as nominal species of Cetotherium but have been either reassigned to other genera or removed from Cetotherium:

Cetotherium furlongi Kellogg, 1925, is known from a partial skull from the Burdigalian of the Vaqueros Formation in California, but the holotype is lost.

Cetotherium gastaldii Strobel, 1875, known from the early Pliocene-age Sabbie d'Asti Formation of the Piedmont region in Italy, is now the type species of the eschrichtiid genus Eschrichtioides.

Cetotherium klinderi Brandt, 1871, is known from an isolated earbone from Miocene sediments in Chişinău, Moldova. Although fragmentary, it does not appear to be congeneric with either of the two valid species of Cetotherium.

Cetotherium maicopicum Spasski, 1951, based on a specimen from the late Miocene of the Russian Caucasus, has been reassigned to the genus Kurdalagonus from the same region.

Cetotherium mayeri Brandt, 1871, known from a partial skeleton, is apparently not congeneric with Cetotherium.