Two New Howler Monkey Species Found in Amazon

Genetic research has uncovered two previously unknown species of howler monkey living in the Amazon rainforest, confirming that the world’s largest tropical forest is more biodiverse than scientists thought. The new howler monkey species, named Alouatta iroi and Alouatta matogrossensis, were reported on 10 November 2026 in a study led by researchers from the University of Salford and international collaborators. The team analysed the genomes of 11 howler monkey species across South and Central America, and the findings not only identified the two new species, but also explained how they are related to other howler monkey species and mapped where each group lives. The work was published in Communications Biology.

The findings come 85 years after the last howler species was described, Alouatta puruensis in 1941, and they highlight the Amazon rainforest as a rich centre of biodiversity. Howler monkeys are known for their loud calls, which can carry for long distances through the forest, and they play an important role in their ecosystems as seed dispersers and as prey for other animals. By comparing whole genomes, the researchers could separate groups that look similar but have been evolving apart for a long time. That genetic detail helps explain the history of howler monkeys and shows how diversity can hide within animals that were previously grouped as a single species.

Why the new howler monkey species matter

The article helps address longstanding gaps in knowledge about the actual number of species that exist and their geographic distributions, gaps that scientists call the Linnean and Wallacean shortfalls. Knowing where each species lives is essential for protecting them, because conservation plans depend on accurate maps of range and habitat. For the Amazon, the discovery is a reminder that even large, well-known animals can remain undescribed, and that genetic tools are now revealing diversity that field observation alone could not separate. Further surveys will help define the ranges of the two new species and assess how they are faring in a forest under pressure.

Source: Phys.org