Shrew Are You? Scientist Discovers Two New Species of Shrews in Museum’s Collection

Hailing from the mountains of Colombia, the new shrews fill in a geographical gap and are among a growing number of species discovered in collections

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Research zoologist Neal Woodman (right) and former museum intern Alec Wilken examine shrew specimens in the National Museum of Natural History’s collections. James Di Loreto, Smithsonian Institution

With more than 148 million specimens and objects, the vast majority of the National Museum of Natural History’s collections are off display. But each of these specimens — whether it be a moth, meteorite, moss or mammoth — tells a story that helps museum researchers make sense of the natural world. Each month, the Specimen Spotlight series will highlight a different specimen or object from the world’s largest natural history collection to shed light on why we collect.

For centuries, researchers had to trek into remote regions of Earth to discover new species of plants and animals. They braved the elements to collect creatures entirely new to science. Thanks in part to these earlier explorers, many new discoveries today are made closer to home.

While expeditions into the field still occur, centuries of collecting have provided natural history museums with a broad representation of plant and animal specimens from across the planet. A sizable portion of these specimens represent species that remain undescribed. Decades after they were initially pinned, pickled or pasted onto sheets, these nameless plants and animals wait for the right researcher to come along and enter them into the ever-expanding encyclopedia of life.

These undescribed organisms are particularly numerous at the National Museum of Natural History, which houses the largest collection of natural specimens in the world. In the last year alone, scientists have discovered several new species stored in the museum’s drawers and cabinets, including an amphibian ancestor named after Kermit the Frog, a bevy of hedgehogs with soft fur and a suite of sea stars that brood babies inside their oral cavities.

Research zoologist Neal Woodman is adept at making similar discoveries. Over his career, Woodman, who is a scientist with the United States Geological Survey working at the museum, has described 23 new species of mammals — a relatively well-known group of animals in which undescribed species are less  common. Woodman’s discoveries include three species of bats and a tree hyrax, a marmot-like mammal that is actually more closely related to elephants and sea cows than rodents.
Research zoologist Neal Woodman examines mummified shrew specimens at the Djehuty tomb site near Luxor, Egypt. Neal Woodman, NMNH

But Woodman’s specialty is describing new species of shrews. Which is no easy feat considering even experts sometimes have difficulty telling these miniature mammals apart. “I'll be the first to admit that many shrews look alike,” he said. “It's easy to mix them up.” To avoid confusion, Woodman makes careful measurements of key morphological features like the size of a shrew’s skull, humerus or tail.

To take such measurements, he needs access to lots of museum specimens. But shrews from some parts of the globe can be tough to come by, even in the museum’s sprawling Division of Mammals. So Woodman relies on specimen exchanges with outside researchers and collectors to fill geographic gaps in the museum’s collection.

One such exchange occurred around 15 years ago, when Woodman worked with a collector to acquire two shrew specimens from the Colombian Andes. One of the shrews was pickled in a jar of ethanol, while the other was preserved as a study skin alongside its skull. Both specimens were collected in the early 1990s from a mountainous region more than 6,500 feet above sea level. Each measured less than three inches long, making them shorter than the standard crayon.

The holotype, or name-bearing, specimen of the shrew Cryptotis andinus was discovered in the collection of the National Museum of Natural History. Neal Woodman, NMNH

Woodman assumed these specimens represented species the museum already had. But the associated locality data revealed the critters were collected in an area where no shrews had previously been reported. He took a closer look at the anatomy of the specimens and quickly realized that “they were nothing like anything that we knew about.”

To confirm his hunch, Woodman analyzed shrew specimens housed in other museum collections. His goal was to determine whether the two Colombian shrew specimens were different from any shrew known to science. This required making detailed measurements and comparing traits like size and coloration between different shrew samples.

“Museums are vital, not only for the work we’re doing right now, but what we could be doing in the future.”

— Neal Woodman, research zoologist NMNH and USGS

These comparisons confirmed that the two shrew specimens represented entirely new species. In a paper published in the Annals of Carnegie Museum in 2023, Woodman described the shrew preserved in alcohol as Cryptotis huttereri, or Rainer’s small-eared shrew, and the shrew preserved as a skin as Cryptotis andinus, or the Southern Colombian small-eared shrew.

Both new species belong to the genus Cryptotis, a group of shrews found primarily in Central America and collectively known as small-eared shrews. In addition to tiny ears, these shrews have soft fur and large forepaws armed with elongated claws.
An Ecuadorian small-eared shrew (Cryptotis montivaga), a relative of the two newly described shrew species from Colombia. Fabián Rodas López, iNaturalist

Woodman hopes that the new species will spur researchers to study these animals further in areas of the Colombian Andes that have been undersampled in the past. Because they have only been observed as museum specimens, next to nothing is known about the ecology of C. huttereri and C. andinus. Finding living individuals in the wild will provide insights into everything from what they eat to how many pups they have.

“All we know is that they exist and approximately where they exist,” Woodman said. “Now it's time to get out there and start actually doing some real science on them.”

X-rays of skulls belonging to two new species of shrews, C. huttereri (left) and C. andinus (right). Neal Woodman, NMNH

According to Woodman, museum collections are vital for understanding the biodiversity of easily overlooked critters like shrews. But they can also reveal larger environmental trends. For example, specimens collected decades apart can help modern scientists track the spread of zoonotic diseases or visualize how particular species respond to climate change.

And there is no telling how much more information these specimens may be able to tell researchers in the future. “Museums are vital, not only for the work we’re doing right now, but what we could be doing in the future,” Woodman said. “People are now getting DNA from specimens that are over 100 years old. These specimens were collected back before the double helix was even known and are now telling us new things.”

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