Scientists who went shopping recently at an Asian food market got more than they bargained for—a rodent unknown to science was being sold as meat.
Discovered in Laos, Southeast Asia, the animal is described as an "oddball rodent" with long whiskers, stubby legs, and a furry tail. But it isn't a squirrel, and it most certainly isn't a rat, says the researcher who first spotted the animal.
Although it's been called a rock rat, the name is misleading, says Robert Timmins, of the Wildlife Conservation Society, based in New York. "It's not at all closely related to typical rats and mice," he said, adding that the description "spineless porcupine" would be more apt.
The animal is believed to represent not only a new species of rodent but also the first mammal family to be discovered in 30 years.
"To find something so distinct in this day and age is just extraordinary," Timmins said. "For all we know, this could be the last remaining mammal family left to be discovered."
While the existence of this dark-colored rodent might be news to scientists, it seems people in the Khammouan region of Laos have long cherished the species—particularly when it's served on a skewer.
Timmins noticed the odd-looking mammal, known locally as the kha-nyou, for sale at an open-air food market. "Rural folks bring in freshly harvested vegetables, fruit, and wildlife," he said. "I knew immediately it was something I had never seen before." Colleagues subsequently found other dead specimens for sale.
Timmins says mammals of this size—the kha-nyou measures 16 inches (40 centimeters) from nose to tail—are usually roasted whole. "You then eat them, crunching up the smaller bones and spitting out the larger ones," he added. "Rats, squirrels, and porcupines are an everyday food item, so the kha-nyou fits right in."
Collected specimens were sent to the Natural History Museum in London.
Paula Jenkins, the museum's zoological collections manager, examined the skull, teeth, bones, and other body features, comparing them with the remains of rodent species stored in the museum's collection.
DNA analysis was also done by C. William Kilpatrick at the University of Vermont in the U.S. Results of the combined research were published recently in the museum's journal Systematics and Biodiversity.
"The animal's characteristics are distinctly different from any mammal species yet known to science," Jenkins said. "As a new mammal, it provides us with an interesting insight into the evolution of this and other rodent families."
The research suggests the kha-nyou is a "living fossil" that split from other rodents many millions of years ago. The rodent also seems to be an ancestor of the hystricognaths, a group of rodents that is spread across the globe and includes porcupines, African mole rats, guinea pigs, and chinchillas.
Until now, the last mammal family to be discovered was that of the bumblebee bat—the world's smallest known mammal. It was found in Thailand in 1974.
The kha-nyou has been given the scientific name Laonastes aenigmamus(Laonastes means "inhabitant of stone" and aenigmamus means "enigmatic mouse"). It is presumed to be a nocturnal plant-eater, living on limestone outcrops in highland rain forests. But since the rodent has yet to be found alive by scientists, it remains largely mysterious.
"There are still many questions over the kha-nyou's status," Timmins said. "Clearly it has a very small range globally, [but it is] probably widespread in the limestone areas of central Laos, so it's probably not going to vanish overnight."
He says that, unlike rats and mice, the rodents give birth to only one offspring at a time, so a precautionary approach should be taken toward their conservation.
"One of the problems with assessing their status is that we don't have any parallels to guide us, since there are no close relatives," Timmins said.
That the existence of such an animal should have remained a secret for so long might seem extraordinary, but mammals endemic to this part of Southeast Asia have a history of being elusive. For instance, the soala, a type of long- horned, rain forest cow, wasn't discovered until the early 1990s.
Likewise, the large-antlered muntjac and the dark Annamite muntjac, two kinds of deer, also remained unknown to the outside world until found in the Annam Cordillera, mountains along the Laos-Vietnam border, in the late 1990s.
"Interestingly, an expedition visited the [Khammouan] area of Laos in 1920 and discovered a new species of bird and a monkey which are also endemic to the limestone," Timmins said. "These were not seen again by scientists until the mid- 1990s."
Of the weird rodent he likens to a spineless porcupine, Timmins added, "Nobody could have predicted this new family."