The saddleback anemonefishes are the most ecologically distinctive lineage of Amphiprion. While all others in the genus are content to live in association with coral reef habitats, the polymnus group has taken to residing in sand flats and seagrass meadows, where there is little, if any, direct competition from congeners. In these environs, the host anemone is most often Haddon’s Carpet Anemone (Stichodactlya haddoni), but they can also be regularly found in the Sebae Anemone (Heteractis crispa).
The most distinctive feature of this group is the slanted middle stripe, which takes on a thickened and abbreviated appearance in certain populations. The darker population found in Indonesia is often mistaken for A. clarkii, but can easily be told apart by its dark caudal fin.
Genetic studies have indicated this group is derived from well within the genus, but traditional morphology based classification has tended to recognize these fishes as their own subgenus, Paramphiprion. Within the group, there are only two recognized taxa, but, more likely, there are four or five unique populations worthy of species recognition. Those from the Coral Triangle are easily differentiated in their patterning, split between northern, western and eastern ecoregions. On the other hand, the Indian Ocean, A. sebae seems quite homogenous across its range, similar to what is seen with the clarkii group.
Amphiprionology 