In 2011, a titi monkey along the banks of Brazil's Roosevelt River caught the eye of researcher Julio César Dalponte. With dozens of recognised species, the titi monkey family is a diverse one ... but the primate Dalponte had spotted looked a little unusual – its colouring didn't seem to match any of the known titi monkeys. Dalponte was intrigued: was this a new species?

Now, a few years and several monkey-tracking expeditions later, a new study published in the scientific journal Papéis Avulsos de Zoologia officially confirms Dalponte's hunch. The new species has been named Callicebus miltoni, or Milton’s titi monkey, in a nod to Brazilian primatologist Dr Milton Thiago de Mello. You can also call it by its (pretty awesome) local name: the 'fire-tailed zogue zogue'.

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A group of Milton's titi monkeys. Image: Adriano Gambarini

Flaming orange tail aside, the monkey also boasts a light grey forehead stripe and some impressive ochre-coloured sideburns, a colour combo that sets it apart from its titi monkey cousins. 

“It goes without saying that we are really excited about this new discovery,” says researcher Felipe Ennes Silva, who collected the data for the new species description, in a press release. “It is always thrilling to find something new in the Amazon, as it reminds us just how special this rainforest is and how lucky we are to have it on our doorstep.

Like others of their kind, the tree-dwelling Milton's titi monkeys live out their lives in small family groups made up of a monogamous pair and their offspring. They're also highly  territorial: their loud warning calls can be heard echoing over the treetops, especially early in the morning and during the rainy season. 

Sadly, although the species has just been described, researchers are already worried about its future survival. Deforestation rates in the region are high, and plans for hydroelectricity dams and new roads also pose a threat. Unable to swim or cross mountainous terrain, the monkeys are essentially confined to a small sliver of lowland rainforest south of the Amazon River. Only around a quarter of this area is protected. 

“The rainforest is under threat like never before, and it will take dedicated, hard work not just by conservationists but by the government and every other sector of society too to make sure that this forest ecosystem can continue to support a wide diversity of life," Silva warns.  

Source: Fauna & Flora International 

All images: Adriano Gambarini, used with permission.