An Australian scientist has found what could be the world's rarest coral in the remote North Pacific Ocean.

The coral bears a close physical resemblance to the critically endangered and fast-vanishing elkhorn coral (Acropora palmata) of the Atlantic Ocean, but genetic analysis has shown it to be a different species.

The unique Pacific elkhorn coral was found during an underwater survey of Arno atoll in the Marshall Islands, by coral researcher Dr Zoe Richards of the ARC Centre of Excellence for Coral Reef Studies (CoECRS).

"When I first saw it, I was absolutely stunned. The huge colonies - five metres across and nearly two metres high with branches like an elk's antlers - were like nothing I'd seen before in the Pacific Ocean.

"So far I have only found this new population of coral to occur along a small stretch of reef at a single atoll in the Marshalls group.

"It grows in relatively shallow water along the exposed reef front and, so far, fewer than 200 colonies are known from that small area.

"The Pacific elkhorn coral has regular divergent blade-like branches that radiate out from single or multiple large central stalks. Its colonies are by far the largest of all the Acropora colonies observed at Arno Atoll, indicating that these are relatively old," she added.

Genetic analysis of the new coral found that its closest relative is Acropora abrotanoides.

"Currently the Pacific elkhorn would be rated as 'data deficient', meaning there isn't enough information to determine whether it is threatened, vulnerable or critically endangered," she explained.

This means that the Pacific elkhorn would join 141 other coral species on the IUCN list whose status is uncertain.

"When Zoe showed me pictures of the Pacific elkhorn, I was shocked," David Miller of CoECRS and James Cook University said.

"The colonies look just like the critically endangered Caribbean species A. palmata, one of the most distinctive of all corals.

"The fact that these colonies might represent a species that has not been seen for over a hundred years (A. rotumana) says something about how much we know about the remote reefs of North Pacific," he said.

The findings were published in journal Systematics and Biodiversity. (ANI)