Newly discovered Amazon fish species is named after ‘The Lord of the Rings’ villain for its odd pattern

By Taylor Nicioli, CNN

(CNN) — Thousands of fish species — about 2,500 of them named — call the Amazon River home, but scientists estimate nearly half of the marine creatures lurking in the massive stretch of water remain undiscovered.

While studying piranhas and pacus in an effort to better assess vital fish biodiversity in the 4,000-mile-long (6,400-kilometer-long) river, an international team of researchers has found and identified a new species of pacu, a piranha relative with a plant-based diet and humanlike teeth.

Besides its odd pearly whites, the newfound species has striking orange and black markings — including a bold vertical black bar stretching across its flank — that the researchers say resemble the fiery eye symbol for the villain Sauron from J.R.R. Tolkien’s “The Lord of the Rings” book and film series. The marks inspired the fish’s name, Myloplus sauron, according to a study published Monday in the journal Neotropical Ichthyology.

“Me and the coauthors thought (the name) would be a nice idea — it really looks like the Sauron’s eye,” said study coauthor Victória Pereira, a graduate student in biology at the University of Paulista in São Paulo, Brazil. The researchers hoped the pop culture reference would draw attention to the fish and efforts to protect biodiversity in the Amazon, Pereira added.

The eye-catching fish is not the only animal named for Tolkien’s Dark Lord. A genus of butterflies was found in May 2023 with spots that looked like eyes on its wings, reminding researchers of the well-known symbol from the trilogy. There is also a species of tree frog, a dung beetle and a genus of dinosaurs named after the character.

The confusion around pacus

Besides Myloplus sauron, the researchers also discovered the species Myloplus aylan, which they described as having a slightly thicker black bar on its flank. The Myloplus genus falls within the Serrasalmidae fish family, which is made up of piranha and pacu species.

Because piranhas and pacus are closely related and have similar features, differentiating the species can be difficult, the authors noted in the study. Both pacu and piranha species can change appearance throughout various stages of their life, and males and females often look different from one another, also making the various species hard to tell apart, according to London’s Natural History Museum.

Myloplus sauron and Myloplus aylan have flat, blunt teeth used to chew on plants, a stark contrast with the razor-sharp teeth found in piranhas, but similar to their other pacu counterparts. While some species of piranhas are known for their carnivorous diets, all species of pacus are primarily herbivores.

Previously, these two new species were grouped in with another fish, Myloplus schomburgkii, because of the shared design of the black mark on the fish’s round body. However, through closer inspection and DNA analysis, researchers found three different species shared the eye-catching design.

Researchers hope to study Myloplus sauron and Myloplus aylan further to learn more about their evolution and relation to other species, Pereira said.

“People studying pacus have recognized for a while that there were multiple species ‘hiding in plain sight,’” said Matthew Kolmann, an assistant professor in the department of biology at the University of Louisville in Kentucky, who has studied the fish. He was not involved with the new study.

“The size of the Amazon and other basins, and their inaccessibility, makes it a place of constant discovery,” Kolmann said in an email. “What this means is that it has and will continue to take generations of scientists’ effort to increase our knowledge of the area.”

Pacus’ impact on their ecosystem

Pacus are important to their ecosystem largely due to their role in spreading seeds through their diet of mostly fruit, which make them vital for the growth of rainforest trees and other plants. The fish tend to spread seeds far from their parent plants, helping to expand the forest and limit disease that easily spreads through crowded trees, Kolmann said.

By discovering and identifying the species that live in certain ecosystems, researchers will be able to better lead conservation efforts to protect animals that are endangered or at risk, Kolmann said. It is particularly important for areas such as the Amazon that are under threat from habitat destruction, he added.

“We run the very real risk of losing thousands, if not hundreds of thousands, of species before we know they even exist, and by proxy, not ever understanding how these species contribute to a healthy functioning ecosystem,” Kolmann said. “Inventorying what species are found where, and when, is the first step in any future conservation effort.”

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