This Western Indian Ocean group is notable for its high degree of endemism, with at least 8 recognizable populations present, two of which have yet to be described. The bulky size, broad host selection and overall appearance have led previous authorities to classify these fishes within a broadly defined clarkii group, but this has not been corroborated with genetic analysis.
Thus far, this “bicinctus group” has appeared nearest to the polymnus group in most molecular phylogenies, but more study is warranted to determine if this is an accurate understanding of the true evolutionary history. There are major ecological differences in their habitat (reefs vs sand flats) and host selection that argue against this, and, given their obvious propensity for speciating, there is reason to believe these may represent a western lineage sister to the Indo-Pacific clarkii species. Lending further support to this is the fact that nowhere are these two groups known to overlap in their distribution, with the closest populations being found along the southern and eastern coasts of Oman.
One interesting phenomenon found in these fishes is the tendency for the caudal fin to remain dark. This is seen in only two populations: A. chrysogaster and A. fuscocaudalis, and it may be indicative of a paedogenetic alteration to their development, as juveniles of all populations tend to possess heavily pigmented tails.
Amphiprionology 