I’ve gotten this from several readers, so thanks to all. According to The Province and several other sources, a defunct spade-toothed beaked whale and her calf (Mesoplodon traversii) washed up on the shores of New Zealand in 2010 and have just been identified as the world’s rarest whale in a new paper in Current Biology (full disclosure: I’m in Mexico and haven’t read the paper. The link is below but you’ll get only the abstract for free.)
Apparently the species was originally described from just a few skull and jaw fragments, but a fleshed-out specimen had never been seen until the pair washed ashore in 2010. Those individuals, however, were misidentified as Gray’s beaked whale (Mesoplodon grayi), and buried. But DNA testing on saved tissue specimens now confirms that the carcasses were indeed those of the spade-toothed beaked whale, since the unearthed skeletal remains are similar to the species described previously and the DNA is quite different from that of Gray’s beaked whale.
The beached whales, an adult and her three-metre male calf, were discovered on Opape Beach on the North Island on New Year’s Eve in 2010. Conservation workers thought they were Gray’s beaked whales and took tissue samples before burying them about nine feet under the sand.
Those samples ended up at the University of Auckland, where scientists did routine tests about six months later. Rochelle Constantine, a co-author of the paper, said she and her colleague Kirsten Thompson couldn’t believe it when the results showed the pair to be the rarest of whales.
“Kirsten and I went quiet. We were pretty stunned,” she said.
Further tests confirmed the discovery. Constantine said they then retested about 160 samples taken from other stranded Gray’s whales but didn’t find any more that had been misidentified.
This year, researchers returned to the beach to exhume the skeletons
Until I see the paper, I won’t know how different the DNA is from the congeneric species, and whether that difference supports species status. I assume, however, that we have DNA from several Gray’s beaked whales, and the DNA of the new whale is quite different from those.
Here’s the mother photographed in 2010; note the snout that resembles the “beak” of a porpoise:
Needless to say, nothing is know of its behavior, and, as Wikipedia says dryly, it is “unlikely to be abundant.”