Two new howler monkey species discovered in Amazon rainforest after 84 years

Scientists have identified two previously unknown howler monkey species in the Amazon rainforest after 84 years. (Photo: Reconecta Project)The Amazon rainforest has revealed two more of its biological secrets, with scientists identifying two previously unrecognised species of howler monkeys through groundbreaking genetic research. The discovery adds to the known biodiversity of the world's largest tropical rainforest, while raising concerns about the survival of these primates as deforestation continues to destroy their habitats.The study, led by researchers from the University of Salford and international collaborators, analysed the genomes of 11 howler monkey species found across South and Central America. The research identified two distinct species, Alouatta iroi and Alouatta matogrossensis, which were previously classified within other known species.Published in Communications Biology, the findings offer a more detailed understanding of how howler monkeys evolved, how their populations are distributed and why the Amazon Basin is home to such remarkable primate diversity.Genetic analysis reveals hidden species diversityTo establish the evolutionary relationships between different howler monkey populations, the researchers combined genome-wide analysis with morphological evidence from museum specimens.The findings revealed that populations previously thought to belong to a single species were, in fact, distinct evolutionary lineages. The team was also able to map their geographical distribution and establish how the newly identified species relate to other howler monkeys.The discovery is particularly significant because the last howler monkey species was described 84 years ago. That species, Alouatta puruensis, was described by Lonnberg in 1941.The research also addresses two major gaps in biodiversity science. The Linnean shortfall refers to the number of species that remain undocumented, while the Wallacean shortfall concerns the lack of information about where different species live.How major Amazon rivers shaped the evolution of primatesGenetic research identified Alouatta iroi and Alouatta matogrossensis as distinct evolutionary lineages. (Photo: Wikipedia)The study also sheds light on the geographical factors that contributed to the evolution of howler monkeys across the continent.Researchers found that major river systems, including the Amazon, Rio Branco and Xingu, have acted as natural barriers for millions of years. By separating monkey populations and restricting their movement between forest regions, these rivers allowed isolated groups to evolve independently.Over time, these geographical divisions contributed to the emergence of distinct species, helping explain the extraordinary diversity of howler monkeys across the Amazon Basin.Deforestation puts newly identified species at riskAlthough the findings are a significant addition to scientific knowledge, they also highlight the conservation challenges facing the Amazon's wildlife.One of the newly recognised species, Alouatta matogrossensis, inhabits southern Amazonia, a region experiencing some of the world's fastest rates of deforestation. The expansion of agricultural land, particularly croplands, along with other human activities, is contributing to the destruction and fragmentation of its habitat.Since the newly identified populations have not previously been assessed for conservation status, their precise level of vulnerability remains unknown. However, researchers warn that habitat loss and environmental changes could place them at considerable risk.Professor Jean Boubli from the University of Salford's Environmental Research & Innovation Centre said: “This discovery comes at a critical time, as increasing deforestation, climate change and habitat loss threaten many Amazonian species before they are fully understood or even discovered by science. We hope these findings will help conservation organisations identify the most vulnerable populations and prioritise protection efforts across the Amazon Basin.”Dr Romina Batista, honorary Postdoctoral Research Associate at the University of Salford, said: "Our study shows that the Amazon still holds remarkable biological secrets, even among well-known animals such as howler monkeys. These findings are particularly important because many of these populations are facing increasing pressure from habitat loss and environmental change. Understanding the different species in existence is the first step towards protecting them."Camera traps capture newly identified monkeys crossing wildlife bridgesThe discovery also connects with conservation work already taking place in the region. Camera-trap footage from artificial canopy bridges in Alta Floresta, Mato Grosso, captured the newly identified Mato Grosso red howler monkey using the crossings to move between fragmented forest areas.One of the images showed a female monkey carrying her infant across a bridge. The footage offers a glimpse of how such structures can help arboreal animals navigate landscapes divided by roads and human activity.The Reconecta Project, led by conservationist and road ecologist Fernanda Abra, works to reduce road mortality among tree-dwelling species by installing canopy bridges and reconnecting fragmented habitats. These crossings provide safer routes for animals that would otherwise have to descend to the ground or risk crossing roads.The initiative could play an important role in protecting species such as Alouatta matogrossensis, particularly as deforestation continues to isolate populations and reduce their natural habitat.