A new species of piranha-like fish has been discovered in the Amazon River after secretly masquerading as another, nearly identical species for nearly 200 years. Scientists have named the newly discovered fish after the dark lord Sauron from the fantasy epic by J. RR Tolkien The Lord of the Rings.
However, the fish is nowhere near as scary as its ominous moniker suggests.
The newly discovered species, Myloplus sauron, is the pacu — a close relative of the piranha, often confused with the iconic freshwater fish. The researchers found M. Sauron while studying the almost identical species M. schomburgkiiwhich was first discovered in the Amazon in 1841 but has since been largely ignored by scientists.
In a new study published June 10 in the journal Neotropical ichthyologyscientists did a genetic analysis of M. schomburgkii a population that reveals it is actually made up of three different species: M. schomburgkii, M. Sauron and M. ailans. After closely examining the fish, the researchers noticed almost imperceptible physiological differences between the three species, including the number of spines and rays on the dorsal fin and the shape of the female’s anal fins.
M. Sauronwhich was described together M.aylans in the new study, it is named after a black band on the side. This streak, which is also present on M. schomburgkii and M. ailansbears a striking resemblance to the Eye of Sauron, a giant fiery eye controlled by the titular villain.
“Its picture looks a lot like the Eye of Sauron, especially with the orange spots on its body,” co-author of the study Rupert Collinssenior curator of fish at the Natural History Museum in London, said in a statement. “As soon as one of my colleagues came up with the name for this fish, we knew it was perfect for it.”
Connected: The Eye of Sauron Volcano and Other Deep Sea Structures Found in Underwater Mordor
Pacus and piranhas, which belong to the Serrasalmidae family, are often thought of as aggressive, bloodthirsty predators. But the majority of both groups are actually omnivores and prefer a mostly plant-based diet. Most pacus, for example, they have flattened, human-like teeth which help them break down plant matter instead of tearing flesh.
Even the purely carnivorous species of piranha are not as aggressive as most people imagine – a misconception fueled in part by President Theodore Roosevelt, who wrote in 1913 that piranhas were “the most ferocious fish in the world” after seeing a demonstration of fish tearing the flesh of a cow in a matter of minutes during a trip to Brazil. However, what Roosevelt actually saw was a group of piranhas that had been purposefully rounded up and starved to drive them into a feeding frenzy.
Despite the similarities between the three species of pacu listed in the new study, researchers aren’t sure how closely related the three fish are. It is possible that they all descended from a single recent ancestor. But it’s also possible that they’re distantly related and all evolved to look the same because it gave them the best chance of survival in their environment — a phenomenon known as convergent evolution.
“There wasn’t enough evidence to suggest whether these three species all descended from a common ancestor or evolved convergently,” Collins said.
As a result, it is possible M. Sauron and M. ailans can be moved to different genera if they are later found to be more closely related to other species, the researchers wrote.
The researchers also identified a potential fourth species of pacu in the Tapajós River—a tributary that flows alongside the Amazon River—that had large black spots instead of stripes on its sides. However, the genetic differences between these fish and M. schomburgkii were “on the edge,” Collins said. Therefore, they are currently labeled as a subpopulation of M. schomburgkii.
