Newly Discovered Monkey Pops Up in Camera Trap Footage
Scientists spotted Alouatta matogrossensis, a new species of howler monkey, while watching videos of animals scrambling across a canopy bridge in Brazil.
It’s a common storyline in conservation—a new species is discovered, and before there’s time to get out the Latin dictionary for naming, scientists realize the animals are already imperiled. Less common: To discover a new threatened species and find out it’s already being protected by an inspiring effort.
That’s what happened in the case of one of the world’s newest howler monkeys, Alouatta matogrossensis. Before an international team of scientists published their findings announcing the new South American species in Communications Biology in October, they reached out to Projeto Reconecta, an initiative that aims to construct numerous rope bridges to span Brazil’s roadways. These crossings act as safe passage for animals in the rainforest canopy, stitching together the tattered fabric of a once pristine ecosystem.
Among thousands of camera-trap photos from the bridges of wildlife using the crossings—including capuchins, marmosets, and titi monkeys—the researchers spotted the new matogrossensis. “We were all amazed that we were providing safe crossing opportunities for a new monkey species,” says Fernanda Abra, a road ecologist and National Geographic Explorer who leads Reconecta.
Those images were “super important,” says study co-author Romina Batista, an evolutionary biologist at the National Institute of Amazonian Research, “knowing that there was a project in that region helping these animals, keeping their gene flow across the fragmented areas. That has a huge impact on maintaining this brand-new species that we just described.”
Howlers are among the largest primates in the Western Hemisphere, found throughout Central and South America, and known for their extremely loud 100-plus decibel calls. Howlers announce themselves so loudly they can be heard miles away—but finding the new species still required painstaking work.
Matogrossensis are found in the Brazilian state Mato Grosso (hence the name), in the southern Amazon Rainforest. While they are a bit darker and redder than their closest relative, the Aloutta sara that lives across the border in Bolivia, an average person might have difficulty telling them apart. Their distinctiveness, instead, lies deeper. The new study compiles genetic evidence from decades of samples found across the Amazon, and reveals this population has likely been its own species for more than half a million years, isolated by rivers on one side, and the bordering Cerrado, a tropical savannah ecosystem, on the other.
Like other species in the region, they are likely in grave danger. “They're found in a place where the forest is at its worst shape in the whole of Brazil,” says study co-author Jean Boubli, a primatologist at the University of Salford in the UK and National Geographic Explorer. In Mato Grasso, expansion of the agricultural industry has historically led to some of the highest deforestation rates in all the Amazon. Over decades, natural habitat has been cleared for soybean crops and cattle pasture. Even roadways built through remote areas are enough to sever animals from one another. Abra says that the rope bridge that matogrossensis was spotted on is near Alta Floresta, a small but growing urban center. “The cities are getting bigger,” Abra says of the municipalities in the region. “So there is more agriculture, agriculture fields, cars everywhere.” That also means more roadkill involving primates.
While scientists have yet to formally list the species with the International Union for Conservation of Nature, Boubli believes “it's either endangered or critically endangered,” based on the degraded state of the local environment.
Previously, scientists would have assumed the howler in Abra’s photo was part of a robust, common species known as the Purus red howler (Alouatta puruensis). Proving it’s a new species with a smaller distribution might unlock more resources and urgency to save it.
Boubli has been exploring the Amazon, collecting samples of primates for nearly 30 years, and still he’s surprised at the biodiversity he continues to find. Indeed, this new paper names not one, but two new species of howler, bringing the researchers’ total count of howler species to 16 so far. The second, now called Alouatta iroi, lives further north in the Amazon. Its name borrows a word for Howler monkey in a Yanomami indigenous language, and it appears to be around 700,000 years old, also cut off from a sister population by a river.
And so, the study reaffirms the power of dividing lines in the rainforest. Natural features like rivers can generate immense biodiversity over hundreds of thousands of years, just as artificial barriers like roadways can destroy it in a few generations.
"We really need to be careful here, because we can't just plow through areas without knowing what was there,” Boubli says. Meanwhile, Abra says her bridges now serve three recently discovered monkey species: the critically endangered Alta Floresta titi monkey, first described in 2019; the Schneider’s marmoset, discovered in 2021; and now the matogrossensis. So far, the spans seem effective at preventing roadkill deaths.
That scientists are still finding new species of big loud conspicuous monkeys makes Boubli wonder about all the untold, more clandestine critters—the beetles, the butterflies, and so on—that also are waiting to be discovered, if we can just keep their ecosystems intact.
