The Beluga Whale is a member of the Monodontidae family, which is in turn part of the toothed whale suborder.    From Wordnik.com.  [KSAT.com - Local News] Reference

Although we focus on research from the study of dolphins, beluga whales (also toothed cetaceans and members of the family Monodontidae) make a signifi cant appearance.    From Wordnik.com.  [NPR Topics: News] Reference