A new species of monkey that purrs like a cat has been found in the Amazon rainforest, according to a World Wildlife Fund (WWF) report that features a compilation of the new species discovered in the Amazon between 2010 and 2013.

The purring monkey (Callicebus caquetensis), also known as the caqueta titi monkey, is one of the 20 species of titi monkey native to the Amazon basin in South America.

"When they (baby caqueta titi monkeys ) feel very content they purr towards each other," Thomas Defler, an American primatologist who helped discover the new species of purring monkey, said in a press release.

As Caquetá titi monkeys are found only in the Amazon, their population is facing threat of extinction due to widespread deforestation, habitat loss, fragmentation and invasive human activities.

"These species form a unique natural heritage that we need to conserve," Claudio Maretti, of the WWF's Living Amazon Initiative, said in the press release. "This means protecting their home -- the amazing Amazon rainforest -- which is under threat from deforestation and dam development."

The purring monkey is one among more than 400 new species of plants and animals that have been found in the rainforest. Flame-patterned lizard, a vegetarian piranha and a thumbnail size frog are among these new finds.

Overall, 258 plants (45 orchids), 84 fish, 58 amphibians, 22 reptiles, 18 birds and one mammal have been recorded.

"The more scientists look, the more they find," Damian Fleming, head of programs for Brazil and the Amazon at WWF in the UK, said in an official statement. "With an average of two new species identified every week for the past four years, it's clear that the extraordinary Amazon remains one of the most important centers of global biodiversity."

Fleming said that the richness and diversity of the Amazon's forests and freshwater habitats that continue to astonish the world face the risk of gradual extinction. As new species continue to surface in the Amazon, it is important to conserve and manage the unique biodiversity.

"Compiling and updating data on new species discovered in the vast extension of the Amazon over the last four years has shown us just how important the region is for humanity and how fundamentally important it is to research it, understand it and conserve it. The destruction of these ecosystems is threatening biodiversity and the services it provides to societies and economies. We cannot allow this natural heritage to be lost forever," Maretti said.