A new species of piranha-like fish has been discovered in the Amazon River after secretly masquerading as another, nearly identical species for almost 200 years. Scientists have named the newly found fish after the dark lord Sauron from JRR Tolkien’s fantasy epic The Lord of the Rings.
However, the fish is not nearly as scary as its ominous name suggests.
Newly identified species, Myloplus Sauron, is a pacu — a close relative of the piranha, which is often mistaken for the iconic freshwater fish. The researchers found M. sauron when studying 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 performed a genetic analysis M. Schomburgkii population, revealing that it actually consisted of three distinct species: M. Schomburgkii, M. sauron and M. aylans. After examining the fish in detail, the researchers also noticed almost imperceptible physiological differences between the three species, including the number of dorsal fin vertebrae and rays and the shape of the anal fins in females.
M. sauronwhich was described next M.aylans in the new study, it is named after the black stripe on its side. This streak, which is also present on M. Schomburgkii and M. aylansit bears a striking resemblance to the “Eye of Sauron” — a gigantic fiery eye wielded by the titular villain.
“Its pattern looks a lot like the Eye of Sauron, especially with the orange spots on its body,” co-author of the study Rupert Collinschief curator of fish at the Natural History Museum in London, said declaration. “As soon as one of my colleagues came up with the name for this fish, we knew it was perfect for it.”
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Pacus and piranhas, both in the Serrasalmidae family, are often considered aggressive, bloodthirsty predators. But most of both groups are actually omnivores, preferring a mostly plant-based diet. Most pacus, e.g. they have flattened, human-like teeth which help them break down plant matter rather than tearing through flesh.
Even purely carnivorous piranha species are not as aggressive as most people imagine – a misconception driven in part by President Theodore Roosevelt, who wrote in 1913 that piranhas were “the wildest fish in the world” after seeing a demonstration of the fish tearing flesh from a cow in minutes during a trip to Brazil. What Roosevelt actually saw, however, was a group of piranhas that had been deliberately rounded up and starved to whip them into a feeding frenzy.
Despite the similarities between the three pacu species identified in the new study, scientists aren’t sure how closely related the three fish are. It is possible that they could all have descended from a single recent ancestor. But it’s also possible that they’re distantly related and all evolved to look alike 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 all three species came from a common ancestor or whether they evolved convergently,” Collins said.
As a result, it is possible that M. sauron and M. aylans they 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 along the Amazon River – that had large black spots on its side instead of stripes. However, the genetic differences between these fish and M. Schomburgkii they were “borderline,” Collins said. Therefore, they are currently referred to as subpopulations M. Schomburgkii.