The record for the world's tiniest land snail didn't last long; the previous record-holder, found in China a month ago, has been surpassed by the discovery an even smaller creature from Borneo, researchers have announced.
Among 48 new species of snails discovered in Malaysian Borneo was Acmella nana (from the Latin "nanus" for "dwarf), a species with a shell just 0.5 millimeters wide.
That makes the previous record-holder, Angustilia dominikae, seem almost giant in comparison at 0.8 millimeters wide.
Researchers have announced Acmella nana and the other 47 news species in a study appearing in the journal ZooKeys.
The snail is so tiny, a microscope was needed to see it in the wild, the researchers say.
However, they knew where to look, they said; snails prefer to inhabit the limestone hills of Borneo, probably because they create their shells out of calcium carbonate, the major material in limestone.
"When we go to a limestone hill, we just bring some strong plastic bags, and we collect a lot of soil and litter and dirt from underneath the limestone cliffs," explains Menno Schilthuizen, professor of evolution from Leiden University in the Netherlands.
After sieving the material down to a certain size, they dump it into a bucket full of water.
"We stir it around a lot so that the sand and clay sinks to the bottom, but the shells — which contain a bubble of air — float," Schilthuizen says.
That's when the microscope comes into play, he says, allowing them to sort and identify the minuscule shells.
The researchers say they don't know what Acmella nana feeds on, since they've observed it alive in the wild; only its empty shells have been discovered so far.
A relative species in Borneo, Acmella polita is known to feed on thin layers of fungi and bacteria clinging to the wet walls in limestone caves.
"Probably, Acmella nana lives in a similar way," Schilthuizen says. Its tiny size could allow it to feed in cracks and crevices too tiny for other snails, he suggests.
The island of Borneo — shared between three countries, Indonesia, Malaysia and Brunei — is home to an estimated 500 species of snails, which play an important role in ecosystems by feeding on dead and decaying matter, the researchers say.
The new record-holder has been found in three different places in Malaysian Borneo, they report.
