‘Rare’ creature lurking in riverbed turns out to be species not seen in 22 years
Knee-deep in a river of northern Thailand, scientists scooped up some sand with a net and sifted through it. Hidden between the grains, they found two “rare” creatures — and rediscovered a species not seen in 22 years.
A team of researchers visited Mae Chaem River in December as part of an “extensive” region-wide wildlife survey with a very specific goal: find some mayflies, Sedtawut Kwanboon and Boonsatien Boonsoong wrote in a study published March 13 in the peer-reviewed journal Check List.
Mayflies are a group of flying insects “known for their extremely short adult life spans and emergence in large numbers in the summer months,” according to Britannica. “Given their incredible abundance, mayflies are key members of local food webs.”
Instead of looking for adult mayflies, researchers were searching for aquatic immature mayflies, known as nymphs, and used nets to scoop sand from the riverbed, the study said.
The method worked.
Researchers found two nymphs of the “rare mayfly species” Behningia baei, the study said. Photos show these brown insects, which blend in with the surrounding sand.
Behningia baei mayflies were first collected in 2002 and described as a new species in 2006, “but no other information has since been added,” researchers said.
From the 2024 collections, researchers concluded that Behningia baei mayflies live in “fine sandy rivers” and have a “broader distribution” than previously thought.
Like other related species of mayfly, Behningia baei mayflies are likely “predators,” living in between sand grains, according to a 2006 study about the species.
Much about Behningia baei mayflies remains a mystery. Still, “these new data about the geographic and habitat distributions of behningiid mayflies helps to fill knowledge gaps and improves our ability to address conservation issues surrounding these rarely seen mayflies, not only in Thailand but also globally,” researchers said.
Mae Chaem River is in the Chiang Mai region of northern Thailand and a roughly 440-mile drive northwest from Bangkok.
This story was originally published April 4, 2025 at 10:06 AM with the headline "‘Rare’ creature lurking in riverbed turns out to be species not seen in 22 years."
