Rare "Mystery Monkey" hybrid of distantly related species found in Borneo - New Style Motorsport

Mischief has taken place in Borneo, Malaysia, when it was discovered that a proboscis monkey and a silvery langur had created a new hybrid. The “mystery monkey” is the product of two distantly related species that now share a habitat and possibly compete for resources as a result of human interference with the landscape.

Hybridization between wild animals is not that rare, but the coming together of such distant animals is rarely seen, say the authors of a new paper published in the International Journal of Primatology. Evidence for species union includes photographs of interspecies mating plus an adult female hybrid believed to have offspring of her own.

The parent species behind the “mystery monkey” hybrid is believed to be the proboscis monkey Nasalis larvatus, Y Trachypithecus cristatus, a kind of silvery langur. Both are found in the Lower Kinabatangan Wildlife Sanctuary in Sabah, Borneo, and are believed to compete for forest space.

COVID-19 meant that researchers had to take an alternative approach to investigating the monkeys, as restrictions meant they had to keep a safe distance. Instead, they used an image library of photographs taken inside the sanctuary to search for clues about the monkeys’ lifestyle, appearance and relationships.

The hybrid was first seen in the photo album as a juvenile, but with fresher images providing more information, they found evidence that it reached adulthood and possibly even had a baby of its own.

The “putative hybrid,” as the study authors affectionately call it, exhibits intermediate characteristics between N. larvatus Y T. cristatus both in its coloration and in the proportions of its extremities. Both species are known to hang out in mixed groups in the area and have even been caught on camera mating, showing that the arena was prepared for a mix of monkeys.

monkey hybrid
Photo of the hybrid and what is believed to be her baby, taken by Nicole Lee, September 7, 2020. Image credit: Lhota et al 2022, International Journal of Primatology, CC BY 4.0

While photographic evidence of the hybrid holding an infant while apparently lactating would indicate that it is fertile, the authors express concern that its existence may be the result of human development and could threaten the future of the species. Forest conversion along the Kinabatangan River has fragmented the habitat of these animals, meaning that they may now represent competitive species sharing limited resources.

The concern is that this could lead to the comparatively larger males of N. larvatus dumping smaller male T. cristatus outside of their groups, which could, over time, lead to their local extinction.

The researchers hope to confirm the identity of the female hybrid with the help of fecal samples in future research once restrictions surrounding COVID-19 are lifted. The noninvasive approach could allow them to pin down their genetic makeup once and for all.

[H/T: Live Science]

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