Japanese whalers and fishermen knew of the smaller, darker beaked whalefor a long time and had their own name for it, “kuro-tsuchi." A specimen 6.2m was stranded in Hokkaido in 2012 but was misidentified as an existing species. Indeed, the scientists who wrote the description used "three individuals from Hokkaido and one additional individual from the United States National Museum of Natural History collection."
The whale's big leap into recognition began when a stranded specimen in Alaska's Prilobof Islands was seen by a biology teacher, who thought it was significant and called a seal researcher he knew, She in turn decided it was significant, not to mention odd, and called n a cetologist, and it went on from there, through the long, hard work of comparing it to identified and unidentified skeletal material and testing its DNA. So this case is a good reminder that "collected" doesn't always mean "classified," and "identified as a new species" takes a while to become "described."
This makes 22 species in the enigmatic group known as the beaked whales, and no one can be sure we know them all.
Photograph from 2016 by Karin Holser, who helped identify the species in the field: I believe this is educational / scientific "fair use." I emailed Holser about it but did not hear back. Note the specimen had been stranded long enough that its characteristic dark coloration has faded, although Mead et. al. note the color is not 100 percent distinguishing from Berardius bairdii, whose range it overlaps.