Rodent Discovered in Laos Defines New Family of Mammals

NEW YORK, New York, May 12, 2005 (ENS) - A new species of rodent found in Laos is so unique that scientists say it represents an entire new family of mammals.

During biodiversity surveys in the Khammouan Limestone National Biodiversity Conservation Area in Central Laos, specimens of the unknown rodent were discovered in a local market being sold for food. Local hunters explained that these "rock rats" were trapped in the nearby limestone karst.

Called "Kha-Nyou" by local people, the species was first discovered by Wildlife Conservation Society scientist Dr. Robert Timmins. Early one morning in 1996, he went to the market to look for unusual animals. "It was for sale on a table next to some vegetables. I knew immediately it was something fairly exciting," he told ENS.


Kha-Nyou found in Laos belong to a newly designated family of mammals. Shown here next to a camera lens cap, this one is about 18 inches (45.7 centimeters) long from nose to tail tip. (Photo courtesy Robert Timmins / WCS Lao Program.)
The Wildlife Conservation Society (WCS), based at New York's Bronx Zoo, is working in Laos to help enact a program designed to halt illegal wildlife trade where poaching has devastated animal populations.

Dr. Mark Robinson, working with WWF Thailand, later discovered other specimens of Kha-Nyou caught by hunters, and he also identified bone fragments in an owl pellet.

The two scientists were independently engaged in biodiversity survey work in the same area between 1996 and 1999.

In 1998 Robinson obtained the heads of two of the animals and photographs of rodents captured by villagers from Mauang Village in Laos' Thakhek District.

Robinson and Timmons decided that the animal they had independently collected was quite different from any yet known from Southeast Asia. So, in 1998, specimens collected by Robinson in 1998 and by Timmons in 1996 were sent to The Natural History Museum in London for comparative analysis with material in the research collection.

On his return to the area in January 1999 Robinson continued his search for the unusual rodents by going with villagers from two adjacent villages, Mauang and Doy, who routinely trap them in bamboo traps, using rice as bait. About 50 traps were set each day, at a single location on bare earth under and between large boulders on steep slopes surrounding karst formations.

From the traps Robinson obtained eight more bodies, one skin and three heads, which were also sent to the Natural History Museum.

Preliminary analysis by Paulina Jenkins in the museum's Zoology Department revealed that the animal was clearly a new genus and species. Its combination of external and skull characteristics were found to be distinctively different from any mammalian species yet known to science.

Tissue samples were sent to the University of Vermont for DNA analysis by biologist C. William Kilpatrick who confirmed the rodent is a creature not previously known.

Based on differences in the skull and bone structure, coupled with the DNA analysis, the authors estimate that the Kha-Nyou diverged from other rodents millions of years ago.

Drs. Timmins and Robinson have never actually met, although they have known about each other for a long time. "There aren't that many people doing conservation work in the region," said Timmins. "We knew of each other."

In their paper published in the April 18 issue of the Natural History Museum's journal "Systematics and Biodiversity," Timmins and Robinson recommend that the common name to be adopted for the new animal should be Kha-nyou or Laotian rock rat.

The new family has been given the scientific name of Laonastidae, the genus is called Laonastes, and the species is called Laonastes aenigmamus.


Head of a Kha-Nyou, or Laotian rock rat (Photo courtesy Robert Timmins / WCS Lao Program.)
Villagers reported that the animals were caught only at night and so are presumed to be nocturnal, in contrast to observations of other small rodents such as treeshrews and ground squirrels. Stomach contents consisted mainly of plant remains, so the researchers believe they are vegetarian.

The scientists find that these rock rats give birth to one offspring at a time, rather than a litter.

Timmins and Robinson write that it is "difficult to assess the species status under IUCN Red List guidelines" because so little is known of the species ecology, and the fact that there are no close relatives from which parallels might be drawn.

Limestone habitats, in general are relatively safe from massive scale destruction, they write, but note that "tree cover in peripheral and accessible karst areas is very vulnerable to loss due to logging and firewood removal."

"Much depends on whether Laonastes is able to use, in addition to scree slopes around the base of the karst, the massive karst limestone formations themselves, whether Laonastes is able to exist in secondary scrub habitats, or if Laonastes is able to tolerate the very high levels of wildlife harvest that is ubiquitous within its known range," the scientists write.

They recommend that the species be given an IUCN Data Deficient listing.

"We're not sure how many exist," he said. "They may be fairly widely distributed in this area of central Laos, there are thousands of square kilometers of this limestone, and it's not clear how specialized they are to certain formations of limestone."


Karst mountains of Central Laos (Photo courtesy Asia Tours)
"To find something so distinct in this day and age is just extraordinary," Dr. Timmins said. "For all we know, this could be the last remaining mammal family left to be discovered."

Dr. Timmins, who also discovered a new species of striped rabbit from the same region in 1999, warns that habitat protection and regulations to reduce unsustainable commercial hunting are vital to safeguarding remaining populations of the Kha-Nyou and other unusual species.

"Skeptics might say that if we are still discovering such amazing new animals, why are people worried about wildlife loss," said Dr. Timmins, "but of course it is an indication of how little we know, and a window onto what we could be losing without ever knowing."

Dr. Timmins returns to IndoChina on an annual basis to do WCS conservation work, mainly determining conservation priorities for various species. One species of concern, he says, is the highly threatened saola, Pseudoryx nghetinhensis, a large ungulate found on the border between Laos and Vietnam, in the wet forests of the Annamite Mountains.

The saola was cataloged for Western science for the first time in 1993 by Vietnamese scientists. "This species is facing extinction in the need future," Timmins said.

The Lao government has not yet responded to the discovery of a new mammal family in their country. "It's a go slow country," said Timmins. "These are very early days yet as to what their reaction will be. Hopefully it will encourage them to conserve biodiversity in their country. They have made laudable efforts, establishing a protected area system, but it remains to be seen if these protected areas can function to conserve species."