Pacific Elkhorn Acropora Coral at Arno Atoll, MI. Photo by Dr Maria Beger

Some unusual elkhorn coral colonies of Acropora have been found growing at Arno Atoll in the Marshall Islands. Only about 200 of these huge, mega colonies were found growing on a small stretch where they greatly resemble the legendary but threatened Caribbean elkhorn coral, Acropora palmata. Dr Zoe Richards of the ARC Centre of Excellence for Coral Reef Studies (CoECRS) who was part of the survey group that made the discovery had this to say of the pacific elkhorn coral:

“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,”

For comparison this is Caribeban Elkhorn Coral, growing in Puerto Rico.

Genetic analysis has revealed that is is not the same species as the Caribbean elkhorn coral but that the Pacific Elkhorn coral is more closely related to Acropora abrotanoides. The question of whether the Pacific Elkhorn corals is technically a new species is a matter of debate. In 1898, over a hundred years ago, a similar description was made for Acropora rotumana from the island of Rotuma in Fiji. Ironically enough the discovery of the Pacific Elkhorn corals was made only a few hundred miles away from Rongelap atoll where the last new species of Acropora, Acropora rongelapensis, was discovered. Perhaps there’s  many more species of popular stony corals yet to be discovered in the Marshall Islands and in other remote Pacific regions.

[Via Science Daily]