In 1941, Abel establishedBalaena belgicabased on a series of fused cervical vertebrae and citing other cranial fragments from the late Neogene of the Antwerp harbor (northern Belgium). Later, Plisnier-Ladame & Quinet (1969) added a neurocranium and other skeletal remains from the same area to this species. Recently, the neurocranium was re-assigned to the genusEubalaenathanks to newer phylogenetic analyses. Here, a new description is provided of materials previously assigned to “Balaena”belgicatogether with taxonomic revisions. Our work suggests that the cervical complex originally designated as the type of “Balaena”belgicais too poorly preserved to be used as such and is assigned to Balaenidae gen. et sp. indet., thus making “Balaena”belgicaa nomen dubium. In addition to the neurocranium, the other remains consist in a fragment of maxilla assigned to Balaenidae gen. et sp. indet. and in a humerus assigned toEubalaenasp. Discovered in the Kruisschans Sands Member of the Lillo Formation (3.2–2.8 Ma, Piacenzian, Late Pliocene), the neurocranium is designated as the holotype of the new speciesEubalaena ianitrix. Our phylogenetic analysis supports a sister-group relationship ofEubalaena ianitrixandEubalaena glacialis, and helps constraining the ages of origin for balaenid clades. Ecological and phylogenetic data suggest thatEubalaena ianitrixmay represent the direct ancestor ofEubalaena glacialis, the latter having evolved through phyletic transformation including body size increase during the temperature decline of the Late Pliocene.