The Australian humpback dolphin is real, distinct and finally has its own name thanks to publication in Marine Mammal Science.

Determining whether similar creatures are the same species or not can be difficult. For some time there has been confusion as to whether humpback dolphins were one species or two. Last year a study by the Wildlife Conservation Society concluded there were actually four – with one species in the Atlantic, two with overlapping ranges in the Indo-Pacific and one in Australian waters.

It takes a while for formal recognition to come through, but now it has, and the Australian version is Sousa sahulensis. "We've finally managed to settle many long-standing questions about humpback dolphins -- particularly how many species actually exist -- using a huge body of data collected over two centuries and analyzed with the latest scientific tools," said Dr Thomas Jefferson of Clymene Enterprises, lead author of the paper declaring the Aussie cetacean's independence from either Indo-Pacific species.

The Australian humpback has darker coloring and a lower dorsal fin than the other species. Debate about the nature of the humpback dolphin dates back to the 19th Century, with Richard Owen, who came up with the name dinosaur, one of the naturalists whose collection was used to finally establish the species division.

The name comes from the Sahul Shelf between Australia and New Guinea, the dolphin's main habitat, which is also the name given to the continent that existed during the Ice Age when New Guinea and Tasmania were united with Australia. The wide gap between the habitats of the Australian and eastern Indo-Pacific humpback dolphin coincides with the Wallace Line between the islands that were connected (at least biologically) to Sahul at the time and those that were part of Asia. 

Splitting of species often prompts the recognition that at least one of the newly recognized animals or plants is endangered, and this is almost certainly the case for S sahulensis, with the population unlikely to exceed a few thousand. Co-author Howard Rosenbaum of the Wildlife Conservation Society says, "Humpback dolphins throughout their range are threatened with fisheries interactions, vessel impacts, and development in their coastal habitats. Efforts to protect humpback dolphins and other coastal dolphins, and their most important habitats are essential for the survival of these species."