Mammals, despite their iconic status, are not the most diverse group in the animal kingdom. With approximately 6,800 known species, they lag behind amphibians, birds, and reptiles in terms of variety. Yet, when people think of biodiversity, mammals such as pandas, orangutans, elephants, and tigers often come to mind. This visibility subjects them to intense scrutiny, making them some of the best-studied and most threatened organisms on Earth. According to the international conservation status inventory, more than one in four mammal species is classified as vulnerable, endangered, or critically endangered.
Given the extensive research on mammals, the discovery of a new species is a rare event. The unveiling of the olinguito in 2013 as the first new carnivorous mammal in the Americas in 35 years, and the identification of the Tapanuli Orangutan as a distinct species in 2017, highlight the rarity of such discoveries. However, identifying a new genus—a taxonomic group that encompasses more than one species—is even more extraordinary. This is precisely what has happened with the recent discovery of a new genus of a small gliding possum in Indonesian Papua, named ‘Tous’.
Finding a Lazarus Species
The journey to this discovery began in 2015 with a single photograph taken by a plantation worker in Indonesian Papua. This worker, part of a citizen science-based biodiversity monitoring project, captured images of an unfamiliar tree-dwelling marsupial. The creature, with its large eyes and furry appearance, bore a resemblance to the Australian greater glider but exhibited distinct features, including a gliding membrane and a prehensile tail.
Upon examining the photographs, scientists realized the animal closely resembled a possum known only from fossil records, initially named Petauroides ayamaruensis. These fossils had been discovered in archaeological sites in West Papua and Papua New Guinea. Previously, it was believed that this lineage of gliding possums, known as hemibelidines, existed only in eastern Australia and had gone extinct around 6,000 years ago. The photograph provided evidence to the contrary, suggesting the existence of a “Lazarus species”—a species thought extinct that reappears alive.
“The photo was evidence this was not the case. What we were looking at appeared to be a ‘Lazarus species’: one that had vanished from the fossil record, only to reappear alive.”
Meet the New Genus, Tous
To confirm the discovery, researchers analyzed the photographs and compared them with fossil teeth from Papua and new partially fossilized materials. The analysis of the size and shape of the teeth indicated that they all referred to the same animal. Further confirmation came from local Indigenous landowners, who recognized the animal as sacred and distinct from other gliders. This led to the naming of the new genus, ‘Tous’, a vernacular term used by local tribes.
Establishing a new genus is exceptionally rare, as it signifies a lineage that has been evolutionarily separate for millions of years. The evidence suggests that Tous belongs to an ancient branch of the possum family tree, once extending from Australia to New Guinea, now surviving in a small, vulnerable area of the Papuan forests. Traditional knowledge indicates that Tous inhabits tree hollows in the tallest rainforest trees and, like Australia’s greater glider, is vulnerable to logging.
Protecting the New Species
The discovery of Tous brings with it significant conservation challenges. The precise location of the initial photograph remains undisclosed to protect the species from wildlife traffickers, as its appealing features make it a potential target. The threat is real, as illustrated by the Javan rhinoceros, which was rediscovered in Vietnam in 1988 but became extinct due to poaching by 2010.
Protecting Tous is complicated by the lack of knowledge about its full range. Evidence suggests it is confined to a small region of New Guinea, where lowland forests face pressures from logging and agriculture. The species’ low reproduction rate, producing only one offspring per year, makes it particularly vulnerable to habitat loss and hunting.
“If conservation builds on that knowledge, and if communities benefit from keeping wildlife alive rather than harvesting it, then Tous may have both a past and a future.”
The discovery of Tous not only highlights the importance of integrating traditional knowledge with scientific research but also underscores the urgent need for conservation efforts that engage local communities. By valuing and preserving the biodiversity that has been part of their heritage for generations, these communities can play a crucial role in ensuring the survival of this remarkable new genus.
This article is republished from The Conversation. It was written by Erik Meijaard, University of Kent; Kristofer M. Helgen, University of Technology Sydney, and Tim Flannery, Australian Museum.
