Victorian researchers have discovered a new species of dolphin living right under their noses on Melbourne's doorstep.

The dolphins are found in Port Phillip Bay, and the Gippsland Lakes and in waters as far afield as Tasmania and South Australia.

Their discovery is cause for much celebration as it is only the third time since the late 19th century that a new dolphin species has been recognised.

The new species will be formally named Tursiops australis.

PhD researcher Kate Charlton-Robb from Monash University discovered the new species after comparing the animal's skulls to those of bottlenose dolphins.

Sorry, this audio has expired Dolphin researcher speaks to AM

"We found that the skull morphology and the external morphology and colouration and their genetics is quite distinct," Ms Charlton-Robb said.

"It's distinct enough from the common bottlenose dolphin that this is actually a new dolphin species.

"So the animals that you would see out in the bay on a normal occasion would be this new species type."

Ms Charlton-Robb says there are only about 150 of the dolphins in the region.

"This animal has been living right under our noses for so many years, and just with combining those two different technologies, with looking at the skull morphology and the DNA, there's still really exciting discoveries to be made.

"The main focus is obviously the conservation of this new species so we can enjoy them for future generations and be able to continue the research," she added.

"It would be a shame to discover something and then and lose it. So we really are working hard to try and protect and conserve these animals."