The most in-depth study of clownfish evolution to date has suggested that the fish may be members of a single genus, rather than two.
The new molecular study by Santini and Polacco, which is due to be published in the journal Gene, has provided evidence to suggest that all clownfishes are descendents of a common ancestor.
This monophyletic origin for the subfamily Amphiprioninae is at odds with morphological taxonomy, which splits the subfamily into two genera: Amphiprion and Premnas.
Although most fishkeepers are aware of only a single species, the Maroon clown, Premnas biaculeatus, the Premnas genus actually contains three species: the other two, Premnas trifasciatus and Premnas leucodesmus, are rarely imported.
Morphologically, Premnas are rather different to Amphiprion species and have a prominent spine on their opercula or gill covers, which is absent in Amphiprion.
The molecular evidence for the monophyly of the Amphiprioninae seems to suggest that all members of the subfamily could be members of a single genus.
The study is the largest done on the Amphiprioninae to date and analysed the genetic material of many species never previously studied in this manner.
Santini and Polacco sequenced the cytochrome b gene, 16S ribosomal RNA gene and the first half of the D-loop, of 23 of the 28-32 of clownfish to reconstruct a molecular phylogeny.
For more details see the paper: Santini S, Polacco G (2006) - Finding Nemo: Molecular phylogeny and evolution of the unusual life style of anemonefish. Gene. 2006.