About a month ago, researchers sifting through soil from China discovered a new microsnail species that’s so tiny, 10 of them could fit side by side in the eye of a sewing needle. With a height of just 0.86 millimeters (0.034 inches), Angustopila dominikae was the world’s smallest land snail… until now.
Meet the world’s newest tiniest snail: Acmella nana from Borneo. Its thin shell is shiny, translucent, and white, and its height ranges between 0.6 and 0.79 millimeters (0.02 and 0.031 inches). Empty shells belonging to this new species were discovered in soil-filled crevices of limestone bedrock in the Malaysian states of Sabah and Sarawak, as well as the Indonesian province East Kalimantan. Acmella nana is only found on the island of Borneo, where it likely eats bacteria and fungi growing on cave walls.
The new species name comes from "nanus," Latin for dwarf, and it’s one of 48 new species of land snails from Sabah, Malaysia, described in ZooKeys this week by Menno Schilthuizen of the Naturalis Biodiversity Center in the Netherlands and his colleagues. Some of these new species were recently discovered hiding on remote mountain tops or in rare vegetation. Others have been known throughout Borneo for decades, but they’re only being formally named now.
Being both tiny and slow, microsnails can easily get stuck and isolated in small patches of habitat for long enough to adapt and even evolve. Seven of the new species, for example, are only found on the 4,095-meter-high (13,435 feet) Mount Kinabalu. One of the snails lives only at the entrance of Loloposon Cave on Mount Trusmadi. "A blazing forest fire at Loloposon Cave could wipe out the entire population of Diplommatina tylocheilos," Schilthuizen says in a statement.
All 48 new species are distinguished by shell characters only. The team had analyzed a huge amount of empty shells that had been extracted from soil samples gathered as early as 1986. "We are aware of the shortcomings of these proceedings," the authors write, "but we feel that investigations into the Sabah snail fauna are better helped by describing the species now rather than by waiting until we have preserved animals of a representative selection of the species."
Image in text: In some areas, a few liters of soil can yield thousands of microsnail shells. Most, such as these from Peninsular Malaysia, measure just one or two millimeters in size. Reuben Clements, Rimba CC-BY 4.0