The whale formally described as new in 2003 after DNA and skull studies was Omura's whale.
Omura's whale, Balaenoptera omurai, is a small rorqual also called the dwarf fin whale. Before its recognition as a distinct species, specimens were often treated as an unusual small form of Bryde's whale. Researchers compared external features, skeletal anatomy and mitochondrial DNA to show that the whales represented a separate lineage.
The formal description appeared in Nature on 20 November 2003, authored by Shiro Wada, Masayuki Oishi and Tadasu Yamada. The evidence included specimens caught by Japanese research vessels in the late 1970s and an adult female found after a boat collision near Tsunoshima, Japan, in 1998. The latter specimen allowed a detailed osteological study of the skull and skeleton.
Omura's whale remains poorly known because it is elusive and generally occurs offshore. Its common name and species name honor Japanese cetologist Hideo Omura. It should not be confused with Rice's whale, a separate and critically endangered Gulf of Mexico species.