It wasn’t so much the eye of this little Amazonian fish that surprised the team of researchers who studied it, as the black stripe on its side, dotted with a few small orange spots. They saw in it the eye of Sauron, the most evil being to emerge from Tolkien’s imagination in The Lord of the Rings. This new species of piranha identified in the Xingu, a tributary of the Amazon, has been named Myloplus sauron. Valeria Machado (Federal University of Amazonia, Brazil), first author of the study published on June 9 in Neotropical Ichthyology, was working with Rupert Collins (British Natural History Museum) to unravel the mysteries of a herbivorous piranha, Myloplus schomburgkii, when, through the study of DNA, they discovered that the very small differences observed between individuals indicated the existence of three distinct species. M. sauron and M. aylan have thus been added to the 100 or so species in the Serrasalmidae family.

A nice set of teeth

Contrary to popular belief, not all piranhas are carnivores. The Myloplus genus includes the pacus, best known in South America. These fish are herbivores, although they do have a nice set of two rows of V-shaped teeth. As adults, they reach a size of between 4 and 16 centimeters. But there are doubts regarding the phylogenetic classification of all these freshwater fish species. The authors of the study said that some of the species that resemble each other may be from different genera that have come closer together as a result of environmental adaptation.

In the event, there was insufficient evidence to determine whether M. schomburgkii, M. sauron and M. aylan descended from a common ancestor, or whether they had evolved convergently. “For bow, we’ve left them in the genus Myloplus, but they might be moved in the future,” said Collins in a statement from the British Museum.

Ichthyology, the branch of zoology that studies fish, has its work cut out for it. According to estimates, 42% of fish species in South America are still unknown.