At less than an inch tall, microsnails can be tough to spot with the naked eye.
But amateur Hungarian shell collector András Hunyadi was up for the challenge on a recent expedition to Guangxi, a region of southern China.
Hunyadi zeroed in on limestone-rich soil, since the miniscule mollusks use calcium carbonate in limestone to build their shells. He collected five samples and sent them to his friend Barna Páll-Gergely, an expert in the land snail family tree.
Sorting through the dirt looking for tiny specimens, Páll-Gergely made a huge find: Seven new species of microsnail that just happened to be the smallest land snails ever discovered. (Also see "Seven New Mini-Frogs Found—Among Smallest Known.")
“As soon as I saw it, I knew I was looking at a new species. Whatever they were, nothing like them had been reported from China,” says Páll-Gergely, whose study was published September 28 in the journal ZooKeys.
The newfound species are so little, ten of them can fit in the eye of a needle. The smallest, with an "astounding" shell height of just 0.03 inch (0.86 millimeter), is named Angustopila dominikae, after Páll-Gergely's wife Dominika Páll-Gergely.
A Rock and a Hard Place
Compared with larger snails, scientists know much less about microsnails, even though they're fairly common worldwide.
Microsnails are most often found in the ocean, especially in crevices of tropical coral reefs, but they also live on land among rocks and caves, where they munch on algae and fungi.
Even Páll-Gergely didn’t know much about microsnails when his friend handed him the soil samples. (See "Love Hurts: What Happens When Snails Stab Their Mates.")
“I had to start from zero,” he says.
So he began searching through research journals, as well as consulting with fellow scientists and visiting museums to study their specimens.
To an untrained eye, the shells of the seven new species look almost the same. To an expert like Páll-Gergely, however, the shells are quite distinct, with various heights; widths; number of shell swirls; shapes of shell openings; and even the number, shape, and size of the snail's teeth, which help protect its soft body from predators.
And since microsnails can’t move very far, scientists know that two identical-looking shells not found near each other are likely separate species.
"They inhabit very small areas, like a single limestone mountain,” Páll-Gergely says.
Eike Neubert, a snail expert at the Natural History Museum in Bern, Switzerland, says the study is good and thorough.
He noted that the scientists didn't find any live snails, and the discovery was made on the basis of shell alone, a common practice. (See "“Extinct” Snail Found Alive—But for How Long?)
But to learn more about these snails, scientists should back up their find with live specimens—and Páll-Gergely agrees.
To Neubert, the discovery of seven new species is important, but not unexpected.
“There is so much life," he says, "in a dimension ordinary people do not see."
Follow Carrie Arnold on Twitter.