Shut the Front Door! Researchers Find ‘Endangered Living Fossil’ Trapdoor Spider
By Melissa Mayer
The first time Jason Bond, Ph.D., saw the Moss Landing State Beach spider he would eventually know as Cryptocteniza kawtak, it was 1997, and the University of California, Davis, professor was still a doctoral student. More than two decades would pass before Bond would trap a male specimen and confirm the spider as a new genus.
A description of that genus, along with a reconstruction of the Euctenizidae family tree and biogeography, make up a recent article published in October in Insect Systematics and Diversity. It’s the first spider paper in the journal’s history, and Bond’s spider also graces the cover of ISD’s September 2020 issue.
Mygalomorphs—trapdoor spiders, tunnel web spiders, and tarantulas—include the Euctenizidae family, which includes 76 trapdoor species and seven genera spanning the United States but largely consolidated in the West and Southwest regions.
These spiders dig burrows and—with one exception—cover the entrances with wafer-like, silk-and-soil trapdoors. To capture prey, a spider positions itself just under the cracked-open trapdoor and springs out in response to vibrations, biting the prey and dragging it into the burrow. Many Euctenizidae spiders keep prey remains packed neatly at the bottom of their burrows.
The males’ mating claspers—a modification to the first pair of walking legs—and pedipalp bulbs—the “boxing glove” structure used to transfer sperm—are species-specific. That’s helpful for entomologists describing a new species, and it’s a tell for female spiders, too. A trapdoor male who saunters up to the burrow and isn’t a suitable mate—he’s the wrong species or maybe he’s off his game—could wind up packed into the burrow with those prey carcasses.
There’s an App for That
Those highly specific mating structures were one reason Bond wanted to find a male specimen before describing the new genus, despite clear molecular evidence it was unique.
“For many years, I’ve been hoping I would inadvertently dig up a mature male, but I never have—to the point to where it was starting to feel kind of hopeless,” says Bond. Those frustrating attempts to find a male went on for 22 years—until a chance photo posted on iNaturalist appeared to be the elusive male. Bond immediately combed the area and then worked with California State Parks to set pitfall traps. And on Bond’s final visit to take out the traps, he hit the jackpot: one single male.
“I knew it was that male when I pulled it out of the trap,” he says. “I forgot my little field microscope … but I ran to Walmart to buy a magnifying glass so I could make absolutely sure that it was what I thought it was!”
That specimen didn’t match the existing Euctenizid genera, confirming what Bond knew: The Moss Landing spider was a whole new genus.
The spider’s genus name is designed to fit with naming conventions and the family. Cryptocteniza combines Greek words meaning “hidden or secret” and “comb” since many of the spiders use subtle comb-like spines near their jaws for digging—plus the genus was hidden in plain sight for so long.
Bond held a contest to crowdsource the species epithet, ultimately choosing a name that honors the spider’s habitat and the Indigenous land it’s found on; kawtak is the Mutsun word for seashore.
Cryptocteniza kawtak probably has good reason for being in a genus all by itself. The authors think it roamed across the southwest during the Cretaceous (over 100 million years ago!) but then died out after the Miocene—except for this one ecologically stranded line on an isolated beach in California.
The combination of age, narrow distribution, and distinctness qualifies the species as an endangered living fossil—and that highlights its precarious position. The spider must contend with invasive plants that carpet the dunes where it burrows, seawater encroachment, and the possibility of getting edged out by the other, more common trapdoor species that live there.
“If there was ever something that I would classify as an endangered species, it would be this particular species,” says Bond. “They’re far less common than some of the species that are actually federally listed.”
Fortunately for this spider, its bird neighbor at Moss Landing—the Western snowy plover—has been listed as endangered for decades and may have been an unwitting ally.
“Sometimes I’ve become a little despondent about the notion that all we seem to care about are feathery and furry things,” says Bond. “But, in this case, the fact that there was a bird that nests there may have very well helped to protect the habitat that’s there.”
To bolster the spider, Bond recommends a formal population survey and careful habitat restoration to remove those invasive plants. He’s working with the California Conservation Genomics Project to sequence a related species and do some low-coverage genome scans on Cryptocteniza kawtak to estimate the genetic variation within the population at Moss Landing.
“Phylogeny, Evolution, and Biogeography of the North American Trapdoor Spider Family Euctenizidae (Araneae: Mygalomorphae) and the Discovery of a New ‘Endangered Living Fossil’ Along California’s Central Coast ”
Insect Systematics and Diversity
Melissa Mayer is a freelance science writer based in Portland, Oregon. Email: email@example.com.
Jason Bond photo by Kathy Keatley Garvey.