Herentalia nigra gen. et sp. nov. is described and compared to other mysticetes. It belongs to Cetotheriidae s.s. and represents one of the best-preserved cetotheriid skulls from the southern border of the North Sea. A comprehensive phylogenetic analysis revealed that it is closely related to Nannocetus and to a Japanese Herpetocetus , suggesting that it belongs to the subfamily Herpetocetinae. The phylogenetic analysis performed tests the recent hypothesis that Caperea marginata belongs to Cetotheriidae. However the present results confirm that the pygmy right whale cannot be considered a member of Cetotheriidae. The phylogenetic analysis was used as the basis for a cladistic palaeobiogeographical analysis of Cetotheriidae that revealed that the family originated in the Pacific basin during the Burdigalian and subsequently underwent a sequence of dispersal and vicariance events that allowed its members to enter other ocean basins. The evolution of Cetotheriidae diversity was punctuated by two distinct ...