U of I researchers discover ‘Vandal’ spider species

MOSCOW, Idaho — Along came a spider, bringing acclaim to the Vandals.

A University of Idaho research team has discovered a previously unknown species of spider, which they believe lives only in an isolated pocket of moist, coniferous forest in the mountains of the Nez Perce-Clearwater National Forests of north-central Idaho. They’ve named the nickel-sized, dark-colored spider Hexura vandal, honoring U of I’s mascot.

Arnau Calatayud-Mascarell, a doctoral student studying entomology; former U of I postdoctoral researcher Ethan J. Briggs; and Chris Hamilton, associate professor in the College of Agricultural and Life Sciences, published a paper detailing their findings Aug. 31 in the journal ZooKeys.

“I think people assume that the U.S. has been pretty well picked over and we have an idea of all of the species in the U.S., and that’s not true at all,” Hamilton said. “This is a great example of that.”

On Sept. 8, 2024, Calatayud was searching the remote Idaho mountains near Kooskia as part of his dissertation research documenting the distribution of spiders in the genus Microhexura. Microhexura spiders are common throughout the Pacific Northwest and are the smallest members of a group known as mygalomorphs. Hamilton’s lab studies mygalomorphs, which include tarantulas, trapdoor spiders, Australian funnel-web spiders and pygmy funnel-web spiders.

Calatayud and Briggs, who was aiding in the surveying effort, were searching for Microhexura at a campground along the Lochsa River near Kooskia when Briggs spotted something odd. Briggs noticed a spider that appeared to be a member of the genus Hexura, known to live in Oregon, Washington and British Columbia, Canada, but not in Idaho. Calatayud reached the same conclusion as Briggs after examining the arachnid — they were looking at a genus previously unseen in Idaho.

“We didn’t care about Microhexura at all after that,” Calatayud said. “We found something way, way cooler.”

They spent another two hours searching around the campground.

Calatayud sent an excited text message to his advisor: “I think we found Hexura!”

Hamilton responded incredulously: “I don’t know. Are you sure?”

Hamilton’s skepticism was quickly erased when he personally examined one of the specimens they brought back to the lab. Better yet, the Idaho specimens appeared to be morphologically distinct from the two known Hexura species found elsewhere in the Pacific Northwest.

Often, genetic testing is necessary to differentiate between closely related species of mygalomorph spiders. The Idaho Vandal spider, however, was visually distinctive. That physical evidence, combined with genetic data, led the researchers to believe the species has been isolated for a long time.

The researchers have returned to the area several times to document the distribution of the newly identified spider, finding it in abundance in a core area of moist, coniferous habitat with moss-covered ground and decaying logs. However, they abruptly stopped seeing the spiders once they ventured into drier areas outside of that pocket of suitable habitat.

“I feel incredibly confident that this is only going to be found in Idaho, and it’s going to be restricted by mountains, increasing elevation and the drying out of habitats, and in some places the physical barriers of rivers, as well,” Hamilton said. “This species is an indicator of a unique, remnant habitat that’s found in Idaho and needs to be looked at more closely and monitored.”

Idaho currently has no state spider, and Hamilton believes a new species that’s endemic to Idaho and named for the state’s land-grant university would be the ideal candidate.

As for Calatayud, an international student from Valencia, Spain, he’s delighted for his part in making a lasting tribute to U of I.

“I think it’s the perfect ending of my stay here at the University of Idaho,” Calatayud said. “I’m very proud to be here with Professor Hamilton, I’m super happy to have this Vandal spider mark my professional career, and it’s probably going to be a part of U of I forever.”

Media contact  

Chris Hamilton
Associate Professor, Department of Entomology, Plant Pathology and Nematology
469-222-5653
hamiltonlab@uidaho.edu