These endangered snails were thought to have disappeared from most of Canada until now

An endangered snail species thought to have disappeared from many parts ofCanada has been discovered in the Upper Thames River watershed, according to a biologist with the Upper Thames River Conservation Authority (UTRCA).

Shagreens area terrestrial snail listed asendangered provincially and federally but recently, they have been confirmed sightings in southwestern Ontario.

"Not only are they rare in Canada, but the lastmainland population may now be gone, making thisnewly found populationthe only one in mainland Canada," said Scott Gillingwater, theUTRCA's species at risk biologist.

Gillingwatersays he saw two shagreensnailsbetween April 2023and April 2024 in Snake Woods Nature Preserve, near Woodstock, an area they've never been recorded inbefore.Mollusk experts have alsoconfirmed the two sightings as legitimate.

Shagreens used to be found in two sites near Leamington, Ont., and on five islands in Lake Erie. More recently, it was thought they only existed on Pelee Island and MiddleIsland due to habitat loss.

Snails were misidentified initially

The snail'soff-brown colour shelland tooth-like protrusions where the body exits the shellare features shared by other local species, but the shagreen lacks a hole on theirbottom side.

The similarities are one reason Gillingwatersaid he at first misidentified a live shagreen he foundwhen he posted his sighting on the citizen science platform iNaturalist in late April 2023.

"I had assumed it was a northern threetooth, so shagreen wasn't even on my radarbecause it's so far south and they share characteristics," Gillingwater said.

That's an identification that stood unchallenged until one month ago, when an iNaturalist user suggested the snail might be a shagreen.

"We contacted Canadian experts ...they were able to confirm that it was shagreen and that it is now the most northerly representation of the species in Canada, and potentially the last mainland population," said Gillingwater.

One year after the first sighting, Gillingwater saw anothershagreen snail in the Woodstock area, this time of a dead specimen.The fact that snails don'tmove long distances on their own, and the only known populations to this point were waterlocked, means it's likely shagreen snails havebeen living in the area all along, he said.

"It's likely that when southwestern Ontario, especially the Carolinian region, was completely forested from one end to the other, before European settlement, these animals were probably in larger populations.At Snake Woods, we have an intact protected forest that has been protected for a long time."

Now that the snails have been found, the work of finding the scope of the newly discovered population, and working to protect them, begins, Gillingwater said. More scientists will be in the area in the near future, taking stock of the shagreen snail population in and around Snake Woods.

That research with be important in making sure the snails are protected from existential threats the most pressing of which could be climate changeand the weather extremes it brings, Gillingwater said, adding that the snails require particular levels of moisture that could become harder to come by with climate change.

Gillingwater also said the discoveryis a testament to the power of citizen-driven, collaborative science on platforms like iNaturalist, where people can record and discuss their findings throughout the world.

"If it weren't for the individual that corrected my mistake, this snail couldhave fallen through the cracks and we may have never known it was there."