In the latest edition of Marine Mammal Science there is an article about a likely new species of Mesoplodon (a beaked whale). As Robert Pitman says in an email tonight, “the last two years two new species of dolphins were also described in the pages of MMS – snubfin dolphin (Orcaella heinsohni) and costero (Sotalia guianensis). Genetics has revolutionized cetacean systematics – talk about cryptic species!”

The new Marine Mammal Science, 23(4): 954–966 (October 2007), carries an article entitled “A Divergent mtDNA Linegage Among Mesoplodon Beaked Whales: Molecular Evidence for a New Species in the Tropical Pacific?” by Merel L. Dalebout, C. Scott Baker, Debbie Steel, Kelly M. Robertson, Susan J. Chivers, William F. Perrin, James G. Mead, Robert V. Grace, and T. David Schofield.

Dalebout, et al. begin their paper with a concise locating of the significance of the DNA findings and recent discoveries issuing from such analysis:

DNA sequence data enable not only the inference of evolutionary relationships and population histories but also represent a powerful tool for uncovering hidden biodiversity, an approach that has become known as “DNA taxonomy” (Dalebout et al. 2002, Meegaskumbura et al. 2002, Hebert et al. 2004). The application of DNA taxonomy to beaked whales (Ziphiidae), the least known of all cetacean families, has led to some significant discoveries in recent years. These include the description of a new species from the North Pacific (Mesoplodon perrini; Dalebout et al. 2002), the resurrection of a long-forgotten species in the Southern Hemisphere (M. traversii; van Helden et al. 2002), and confirmation of the identity of the enigmatic “tropical bottlenose whale” (Indopacetus pacificus; Dalebout et al. 2003). The framework for these findings was provided by comprehensive data sets of DNA reference sequences for two mitochondrial (mtDNA) genes, the control region (CR) and cytochrome b (CYB), derived from validated voucher specimens identified by experts in beaked whale morphology.

During the sequencing of worldwide data sets, the scientists began to notice something, a couple tissue samples stood out. They found there was a highly divergent lineage represented by several recently discovered specimens from the tropical Pacific. They wrote that this “lineage is represented by two skulls (adult female 2 and immature of unknown sex) and associated tissue samples recovered from Palmyra Atoll Wildlife Refuge (5◦ 52 N, 162◦ 06 W), which appeared to be ginkgo-toothed beaked whales M. ginkgodens based on cranial morphology (as determined by WFP and JGM), and two tissue samples 3 collected from Tabiteuea Atoll, Republic of Kiribati (Gilbert Islands; 1◦ 24 N, 173◦ 6 E).”

But these specimens differ from M. ginkgodens. Found in the tropical and temperate waters of the Indo-Pacific, M. ginkgodens was first described in 1958 from a specimen collected in Tokyo, Japan.

The authors of the paper suggest that the Kiribati and Palmyra specimens could be a distinct subspecies of M. ginkgodens or a new species.

It appears another new beaked whale discovery has been made.