The newest species of cetacean to be recognized by science is Deraniyagala's beaked whale Mesoplodon hotaula. This little-known marine cetacean, reported from seven locations in the Indian and Pacific Oceans, was formally described and designated as a new species in February 2014, just a month after the formal recognition of the newest species of freshwater cetacean – the Araguaian river dolphin Inia araguaiaensis. It was first classified as a valid species back in 1963 by mammalogist Dr Paules E.P. Deraniyagala, who based his decision on a specimen from Sri Lanka. However, his classification was subsequently discounted by other researchers, and this cetacean was merged with the Japanese beaked whale M. ginkgodens until the new study revealed genetic and morphological differences that fully justified Deraniyagala's opinion, so it is now re-elevated accordingly as a separate species in its own right. This newly recognised species of beaked whale belonging to the genus Mesoplodon raises the total number of known species within this genus to 15. This is a far higher tally than that of any other cetacean genus. Ironically, however, its species are also, collectively, the least known of all cetaceans.