Tiny shelled creature — ‘world’s smallest’ ever found — is new species in Mexico
.jpeg "The new species was found in a freshwater spring in a recreational park in Mexico.")
In the southern hills of the Mexico state of Coahuila, water bubbles from below the surface to create crystal clear pools between the rocks.
The freshwater springs are known as Los Chorros, the jets, and are part of a popular recreational park a few miles outside the town of Arteaga.
One spring, or manantial, is fed by groundwater that flows from a small orifice in the rock to create the larger pool. It is here that researchers found an “extremely tiny” shell on the silted bottom.
It’s a new species — and possibly the “world’s smallest freshwater snail.”
Armed with a “special spoon,” researchers sifted through the fine sand and sediment between July and December 2024, according to a study published July 10 in the peer-reviewed journal Zootaxa.
As the sand fell away, a total of 85 little shells were left behind from one part of the park, and one shell was found in a nearby area about 500 feet downstream, researchers said.
The white shells were “very small” or “minute,” and measured just 0.03 inches across with a curled shape creating 2.3 whorls, according to the study.
The peristome, or lip opening of the shell, is “slightly flared to trumpet-like,” researchers said.
“The focus of this sampling was actually a fish endemic to this spring, but snails were also found in the samples,” Alexander Czaja, a professor at Juárez University of the State of Durango and lead author on the study, told McClatchy News in an email.
“I’ve been working for several years on subterranean snail species, which are difficult to access, and that’s why you almost always get dried shells that have been brought to the surface by the current,” Czaja said. “I quickly realized it was a new species.”
The snail itself wasn’t found with the shells, but the shell was enough to diagnose the animal, Czaja said.
The new species was named Microphreatus saltillensis, or the Chorros cavesnail, according to the study.
The scientific name honors the nearby city of Saltillo, researchers said.
“Subterranean snails are, due to their habitat where they live among grains of sand, very small by nature, usually between (0.03 and 0.11 inches), but this snail seemed very small to me,” Czaja said. “After weeks of checking the specialized literature, it turned out it is actually the smallest freshwater snail known to date.”
The second smallest is a subterranean snail from Spain, Czaja said.
Researchers pointed out that not only is the snail a new species, but it also doesn’t belong to a known genus, meaning it has created its own grouping of snails.
“I would like to add that we have included in this new genus a species from Texas that was described under another generic name and is now called Microphreatus coronae (Hershler, 1987) Czaja comb. nov. (approx. 0.03 inches in size),” Czaja said. “With that, this new genus Microphreatus has two species, one in Texas and another in Coahuila, Mexico.”
Coahuila is in northern Mexico, southwest of the border with Texas.
The study was completed through a joint collaboration of the faculty of biological science at the Juárez University of the State of Durango. The research team includes Czaja, Gabriel Fermando Cardoza-Martínez, Jorge Luis Becerra-López, José Luis Estrada-Rodríguez, Fernando Alonzo-Rojo, Verónica Ávila-Rodríguez and Ana Alejandra Valenzuela-García.
This story was originally published July 11, 2025 at 6:00 PM with the headline "Tiny shelled creature — ‘world’s smallest’ ever found — is new species in Mexico."
