New species of shrew discovered on a single mountaintop in the Philippines

  • The newly described Palawanosorex muscorum or the Palawan moss shrew is known to live only near the peak of Mount Mantalingahan in southern Palawan Island in the Philippines.
  • The shrew has a stout body and broad fore feet with long claws, which it uses to dig through humus on the forest floor to look for earthworms.
  • The moss shrew has no close known relatives in Asia, and how it came to live on Mount Mantalingahan is a mystery, researchers say.

Scientists have described a new species of shrew that’s known to live only near the top of Mount Mantalingahan, the highest mountain in southern Palawan Island in the Philippines.

The animal was first spotted in 2007 by the late Danilo “Danny” Balete, a Filipino scientist and research associate at the Field Museum in Chicago, U.S., when his team was surveying the mountain’s biodiversity. But they could not identify the species. Now, Balete’s collegues have confirmed that the shrew found near the mountain’s peak is not just a new species, but belongs to an entirely new genus.

The shrew, dubbed Palawanosorex muscorum or the Palawan moss shrew, has a stout body and broad fore feet with long claws, which it uses to dig through humus on the forest floor to look for earthworms, the researchers report in a new study published in the Journal of Mammology. The shrew also has a short tail covered by short, dense fur. By contrast, the Palawan shrew (Crocidura palawanensis), a species that’s endemic to the Philippines, has a slender body, slender feet and a very long tail covered with long bristles.

So far, the tiny grey Palawan moss shrew has been spotted only in forests closer to the peak of the 2,086-meter-tall (6,844-foot) Mount Mantalingahan, between 1,550 to 1,950 meters (5,085 feet and 6,398 feet). In fact, the shrew is one of three mammal species that are known to occur only on Mount Mantalingahan, and nowhere else. The other two species are the Palawan montane squirrel (Sundasciurus rabori) and the Palawan soft-furred mountain rat (Palawanomys furvus).

“There are entire countries that don’t have three unique mammal species — so for there to be three species on one mountain, on one island, in one country is really something,” Lawrence R. Heaney, Negaunee curator of mammals at the Field Museum in Chicago, said in a statement.

The reason for Mount Mantalingahan’s rich diversity, the researchers say, is that it’s a “sky island” — an isolated mountain that’s very different from the surrounding lowlands, creating unique habitats for animals and plants to flourish in.

“There could be many new species on these high mountainous regions in the Philippines, but because they are so high, and hard to get to, knowledge of their existence is awfully limited,” Heaney said.

Palawanosorex muscorum was found on Mt. Mantalingahan, a mountain on Palawan Island in the Philippines. Image by Danilo Balete.

How the Palawan moss shrew came to live on Mount Mantalingahan, however, is still a mystery, the researchers say.

The team estimates that the Palawan moss shrew split evolutionarily from its closest known relatives some 10 million years ago. Mount Mantalingahan and other Palawan high peaks, however, began rising above sea level not more than 5 million years ago, reaching their current elevations more recently, the authors write.

“Given this history, it seems unlikely that P. muscorum occurred on Palawan before 5 Ma [5 million years ago] and may have arrived much more recently,” the authors add.

The researchers speculate that Palawanosorex came to Palawan via Borneo within the last few million years.

“We hypothesize that Palawanosorex reached Palawan from Borneo during one of the periods of Pleistocene low sea level, when the 2 islands either were joined by a continuous land bridge or were separated by only a narrow channel,” the team writes. “If this was the case, a living relative may yet be found on Borneo or other nearby area. Given that shrews are currently rather poorly sampled on Borneo, especially at high elevation, we recommend that comprehensive surveys be conducted.”

The newly discovered Palawan moss shrew from the Philippines does not resemble any other type of shrew or have close relatives in Asia or elsewhere. Image by Danilo Balete.

Much of the Palawan moss shrew’s habitat is currently undisturbed by human activity. And the researchers hope that it will stay this way, especially since Mount Mantalingahan functions as an important watershed, regulating water flow in Palawan.

Sky islands “are where most of the water comes from that people in the lowlands depend on,” Heaney said. “If you want to protect your watersheds, you’ve got to protect your habitats.”

Citation:

Hutterer, R., Balete, D. S., Giarla, T. C., Heaney, L. R. & Esselstyn, J. A. A new genus and species of shrew (Mammalia: Soricidae) from Palawan Island, Philippines. Journal of Mammology. DOI:10.1093/jmammal/gyy041.

This story first appeared on Mongabay

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