A new breed of dolphin has been identified in Australia, genetic testing has confirmed.

The Australian snubfin dolphin (Orcaella heinsohni) has a distinctive stubby dorsal fin and rounded nose. It swims in shallow waters off Australia's northern coast.

Scientists had thought the snubfin was a related species called the Irrawaddy dolphin (Orcaella brevirostris), which is found in Australia and in Asian rivers.

The snubfin dolphin (Courtesy: Isabel Beasley)

Isabel Beasley, a doctoral candidate at James Cook University, suspected the snubfins were a distinct species after she noticed size and colour differences between the Asian and Australian populations.

Snubfins are tri-coloured dolphins ranging from dark brown to white; the Irrawaddy is slate grey with a white belly, Beasley said.

To back up the new species designation, Beasley and Peter Arnold, a curator at the Museum of Tropical Queensland watched both types of dolphins at sea. They also examined the dolphins' skulls and measured the mammals.

The pair sent DNA samples to the National Oceanic and Atmospheric Administration's Southwest Fisheries Science Center in La Jolla, Calif., which confirmed snubfin's separate status as a species.

"Given that the Australian snubfin dolphin appears to be restricted to Australian, and possibly Papua New Guinea waters, Australia now has significant national and international obligations to research and conserve remaining populations," Arnold said in a statement.

The researchers said they reported the discovery in the Marine Mammal Science Journal in the hopes of helping to save the dolphins.

The scientific name of the new species honours Australian researcher George Heinsohn. His studies on stranded dolphin carcasses in the 1960s and 1970s contributed to the new species designation, the pair said.

with files from the Australian Broadcasting Corporation