Volume 39
Issue 2


Myotis crypticus



Colony size

10 to 30 (estimated)


10 grams


Insectivorous and has characteristics that suggest it may be a spider specialist (Arachnophagous)




Widespread throughout most of Spain, southern France, Italy, and the northern Alps

Species Study

Cryptic Myotis

The 1,400th species of bat was hiding right under researchers’ noses

by Christie Wilcox

The Natterer’s bat (Myotis nattereri) is one of Europe’s most widespread bats and is easy to identify. At least, that’s what Dr. Manuel Ruedi, curator of mammals and birds for the Natural History Museum of Geneva, thought when his colleagues asked him to collect genetic samples from the animals for research on their autumn swarming behaviors.

After Dr. Ruedi submitted the samples, his colleague told him he’d misidentified the bats. He thought maybe he’d been tired and made a few mistakes, but that wasn’t the case.

“When she told me that I misidentified all the M. nattereri, I could not believe it,” he says. “I know these bats by heart.”

And yet, the genetic data were clear: The bats he’d taken samples from were not Natterer’s bats.

Unbeknownst to Dr. Ruedi, fellow chiropterologists in Spain were making the same discovery. Dr. Javier Juste and his colleagues at the Doñana Biological Station were using genetics to determine whether the Strait of Gibraltar was acting as a barrier of sorts, separating populations of bats in Europe from their counterparts in Africa.

At the time, the Natterer’s bat was thought to range from Morocco all the way to Scandinavia and east into Russia, but Dr. Juste and his team thought the ones in Africa might be

distinct from the ones in Europe.

As it turned out, they were. But the Natterer’s bats in Spain were actually two different species, and neither one was the real Natterer’s bat.

In search of new intel

“That was a real blow,” Dr. Juste says, because it meant that everything they thought they knew about these bats was wrong.

Most of the research conducted on Natterer’s bats was performed in northern parts of Europe, in locations like the United Kingdom. Almost everything scientists knew about these bats’ behavior, from where they roost to what they eat, was garnered by studying true Natterer’s bats. While it’s likely this closely related species is similar, scientists can’t be certain.

Dr. Juste knew they had to figure out exactly where this mysterious new bat lives. Then they could determine which previous studies focused on true Natterer’s bats, and which ones may provide valuable intel about the new species.

He put graduate student Irene Salicini in charge of sorting out the messy tangle of species. She, in turn, reached out to Dr. Sébastien Puechmaille in France, who had also spotted this as-of-yet-unnamed species, previously assumed to be M. nattereri. She also reached out to Dr. Ruedi in Switzerland, in hopes of comparing the new species with Swiss Natterer’s bats.

 “It took some time to coordinate our efforts, but eventually, we decided to unite our efforts and samples to write a formal paper describing this new species,” Dr. Ruedi says. They decided to call the bat cryptic myotis—Myotis crypticus—for obvious reasons.

To this day, Dr. Ruedi can’t tell the two animals apart by looks alone. The only way to know if a bat is a Natterer’s or a cryptic myotis is to sequence its DNA, though the researchers hope further work on the animals will reveal visible features, which can be used to tell them apart.

The similarities likely extend beyond looks. For example, it’s well-known that Natterer’s bats specialize in eating spiders. They will fly low across grassy areas and pluck an unlucky arachnid right from its web. Along the edge of the bat’s tail are special stiff hairs, which are believed to help them feel where spiders are and wipe off any sticky web material. The cryptic myotis also has these specialized hairs, but it’s still unknown whether the bats actually dine on spiders.

Not the first—and unlikely the last

One way the two species seem to diverge is in their roosting behaviors. Natterer’s bats tend to prefer human-made structures like churches and attics, while cryptic myotis seem to prefer to roost in tree cavities. That makes the animals’ roosts much harder to find, Dr. Ruedi notes—as if the cryptic myotis wasn’t mysterious enough.

 It’s clear more information is needed. Right now, researchers don’t know much. They don’t know what habitats or prey these bats rely on, or how many individuals snuggle together

in one roost. They don’t yet know how many exist.

 One question on everyone’s mind is how these Natterer’s look-alikes interact with actual Natterer’s bats. Dr. Juste points out such similar appearances may indicate hybridization, and indeed, recent studies suggest these species swap genes periodically—something thought to be rare among mammals. A lot of “fascinating evolutionary scenarios” are possible, says Dr. Juste.

 But perhaps the most fascinating part of this story is that this is not the first—and unlikely to be the last—time new species are found right under our noses. Back in the 1990s, researchers realized one of the most common bats in Europe was actually two different species. In the past 20 years, six new bats have been discovered on the continent—and that’s in an area where bats are well-studied, “So imagine,” Dr. Ruedi says, how many species of bats elsewhere in the world “are awaiting discovery.”