Identification of the enigmatic Deraniyagala’s beaked whale

It is essential to discover and identify animals in species level in the wild to achieve the collection of baseline data and benefit better understanding and conservation of the rare species. However, this is far from being realized for many beaked whales in the deep sea, including the Deraniyagala's beaked whale (<i>Mesoplodon hotaula</i>), which is one of the least-known whales with no confirmed live sightings at sea yet all over the world. Here, we provide the first robust field identification of <i>M. hotaula</i>, by integrating DNA sequencing of skin biopsies, acoustic data, and photographs. Our discovery illustrates that <i>M. hotaula</i> has distinguishing acoustic and morphological characteristics, enabling us to distinguish it from other mesoplodonts in the wild. The identification of <i>M. hotaula</i> in species level is rapidly advancing our knowledge on its distribution range, habitat characteristics, behavior, ontogenetic color pattern development, group size and structure, and potential threats.