Genetic Study Finds Two New Amazon Howler Monkey Species

A genetic study of howler monkeys has identified two Amazonian species that science had not formally recognized before, Mongabay reported. They are the Pantepui red howler monkey (Alouatta iroi) in northwestern Amazonia and the Mato Grosso red howler monkey (Alouatta matogrossensis) in the southern Brazilian Amazon.

The researchers say A. matogrossensis may qualify as critically endangered, because its range overlaps with Brazil’s arc of deforestation. A formal assessment of its status is still needed.

How the new species were told apart

The team examined genetic relationships across the whole howler monkey genus, Alouatta, combining genomic data, physical characteristics and museum specimens. The work draws on more than a decade of fieldwork and sample collection.

Lead author Romina Batista, a biologist at the University of Salford in the UK and Brazil’s National Institute of Amazonian Research, analyzed more than 2 terabytes of raw genomic data. According to Mongabay, that volume of data exposed evolutionary differences that earlier studies had missed.

One pattern appeared while she was reviewing the results: monkeys living on opposite sides of the Branco River in northern Brazil formed separate genetic lineages. Batista recalled phoning co-author Jean Boubli to say “there is something different here.” Physical traits backed up the genetic split. A. iroi, for example, has more yellowish fur.

What museum collections added

Historical specimens held in natural history museums helped the researchers pin down the features that set the populations apart. Because the specimens were still available, the scientists could return to older material and examine it with newer research tools. Batista said the findings show why natural history collections need to be preserved.

A proposed third species in the Caribbean

The study also reaches beyond the Amazon. It recommends that the howler monkeys of Trinidad and Tobago, currently classified as A. seniculus insulanus, be recognized as their own species, A. insulanus. Mongabay describes this Caribbean population as potentially distinct, and the study prompted the researchers to reconsider how several populations are classified.

Threats facing the newly recognized monkeys

Agricultural development in the arc of deforestation has contributed to forest fragmentation and extensive habitat loss across the range of A. matogrossensis. In Mato Grosso, the Reconecta project has installed canopy bridges to reconnect fragmented forests. Researchers have documented the species using these structures, including a female carrying an infant.

A. iroi faces a different potential threat. The proposed Bem Querer hydroelectric dam on the Branco River could affect it and its close relative, A. macconnelli.

Why it matters

A species with no formal name and no formal assessment is easy to overlook in conservation planning. The researchers are sharing distribution data with colleagues and the public to support a potential assessment by the IUCN, the body that evaluates extinction risk. “We need to evaluate it urgently,” Batista said of A. matogrossensis.

The result also adds to the broader count of living things scientists have catalogued, a figure that remains an estimate. For background on how that count is made, see how many species are known and how many are thought to exist.

Batista described the work as one piece of the puzzle of how Amazonian biodiversity evolved. Two of the Amazon’s red howler monkeys now have names of their own, and a third population in the Caribbean may be next.

Source: Mongabay