Guwahati: Deep inside Meghalaya’s caves, where light fades and humidity hangs in the air, researchers have identified something almost invisible—a land snail no bigger than a grain of sand, yet spread across much of Asia.
The species, Angustopila milium, measures just about one millimetre. It was identified from shell samples collected in 2022 from Krem Puri and Mawjymbuin caves by a team comprising Nipu Kumar Das, N.A. Aravind, András Hunyadi and Barna Páll-Gergely.
This is the first time the species has been recorded from cave environments in Meghalaya, offering fresh insight into the region’s largely unexplored subterranean biodiversity.
What initially appeared to be a local species turned out to be far more significant.
“This study began after I received a grant from the Malacological Society of London to explore molluscan diversity in Meghalaya’s caves,” said Das. “The shells we collected were first thought to be unique, but detailed examination showed they matched Angustopila elevata.”
Further comparisons, including records from Nepal, confirmed the finding—establishing that A. elevata is in fact the same species as Angustopila milium. The reclassification significantly expands its known range.
From the limestone caves of Meghalaya to landscapes across India, Nepal, Thailand, Laos, Vietnam and southern China, the tiny snail now stands out as one of the most widely distributed land snails in South and Southeast Asia.
“It is remarkable that such a minute snail can occur across such a vast region,” said co-author Aravind, pointing to unanswered questions about how the species disperses and adapts to different environments.
Inside the caves, the shells were found in varied microhabitats—on dry walls near entrances, in dimly lit twilight zones, and on moss-covered rock surfaces. However, researchers caution against assuming it is a true cave-dweller, noting that the shells may have been carried in by water or other natural processes.
Beyond taxonomy, the discovery highlights both the richness and fragility of Meghalaya’s cave ecosystems.
Krem Puri, the world’s longest sandstone cave, and Mawjymbuin are well-known tourist sites. Scientists warn that increasing footfall could disturb delicate cave conditions, altering humidity and temperature in ways that may threaten microscopic life forms that often go unnoticed.
The study also raises a broader scientific question. Such a wide distribution, researchers note, could indicate that what appears to be a single species may actually represent a group of closely related, visually similar species—something only genetic studies can confirm.
For now, the finding serves as a reminder of how much remains hidden beneath Meghalaya’s surface.
Even at just one millimetre, this snail is telling a much larger story.
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