The sovereign nation of Niue is comprised of just a single small speck of volcanic rock located due east of the Tongan Trench. Few have ever heard of it and fewer still could point it out on a map, but it’s an interesting region from a biogeographical perspective. It exists on the edge of Melanesia and Polynesia, two massive regions of the Pacific with distinctive faunae. Since there are relatively few species of Amphiprion that extend this far east, we don’t see as much evidence for this as we do in some other groups of reef fishes, but close examination still reveals a faunal break.
The best example of this might be Amphiprion pacificus, a species known only from the westernmost edge of Polynesia at Samoa, Wallis & Futuna and Tuvalu. The Tongan and Samoan populations in the melanopus group may also adhere to this pattern, being noticeably different than their carmine brothers at Fiji.
Only one other group is known from Polynesia: the widespread Central Pacific complex containing the Bluestripe Anemonefish (A. chrysopterus) and its many regional variants. The local Fijian species can be recognized for its entirely yellow fins, thick stripes and dark colors, while a similar form from French Polynesia differs in having thinner, often broken, stripes and a brown, rather than black, hue.
The video I’ve shared here is important as it offers a rare glimpse into the biogeographical relationship the remote island of Niue may share with its more westerly neighbors. The specimens seen in this brief clip possess far more in common with the fish from Fiji than any of their Polynesian relatives from the east. This has been seen before in other groups of reef creatues, such as the recent study of Veron et al 2015 which examined stony corals across the Indo-Pacific.
It’s quite likely that we could expect Amphiprion pacificus to also turn up here if this relationship holds true, but, with so little recreational diving taking place in this far-off land, it will probably be a great, long while before we know the full extent of the anemonefish fauna found at Niue.
Amphiprionology 