New 486-Legged Millipede Species Found Near Los Angeles

The discovery by two naturalists demonstrates that unknown creatures can lie “right below our feet”

The Los Angeles thread millipede (Illacme socal) Photo by Paul Marek for Virginia Tech

Naturalists Cedric Lee and James Bailey were out hunting for slugs just outside Los Angeles in 2018, when they came across an unfamiliar animal: a tiny, translucent millipede.

Though only about the size of a small paperclip, the creature had an almost otherworldly appearance, with 486 legs and an alien-like head. Bailey knew at once the millipede must be a yet-to-be-described species, writes Eric Lagatta for USA TODAY.  

“There’s been very few moments where I uncovered something and knew right away it was a new species,” Bailey tells the publication. “This discovery felt fateful in that regard.”

The duo posted the invertebrate to iNaturalist, a citizen science app, where it caught the attention of Virginia Tech entomologist Paul E. Marek, writes Corinne Purtill for the Los Angeles Times. While visiting family in Los Angeles for Christmas that year, Marek and his wife traveled to Whiting Ranch, where the millipede was discovered, to see if they could collect some of the creatures. After a few days of searching, they found both male and female specimens, scooped them up (along with a bit of soil) into plastic vials and brought them back to Marek’s lab in Virginia. 

With DNA sequencing and a close look at the millipedes’ structure, Marek confirmed that the pair of naturalists had uncovered a new species—and only the third in the genus Illacme. In a paper published in ZooKeys last month, Lee, Bailey, Marek and their colleagues dubbed the invertebrate the Los Angeles thread millipede (Illacme socal). It joins about 13,000 named millipede species worldwide. 

Millipedes and centipedes are not technically insects—they are actually arthropods, more closely related to lobsters, crayfish and shrimp. They typically dwell in moist areas and are more active at night. 

Contrary to what their name suggests, most millipedes don’t actually have 1,000 legs. In fact, only one species discovered in 2021 has reached the distinction of a “true millipede,” breaking the leg record with 1,306 limbs. The creatures are among the oldest land animals, having first appeared on Earth about 420 million years ago

While their centipede relatives are carnivores, millipedes tend to feed on decaying plant matter—filling an important role in the ecosystem as detritivores.

“I kind of think about them as the little garbagemen of the forest,” Marek tells the L.A. Times. “They just kind of truck around, eat detritus, poop it out, and it’s soil.”

Much is still unknown about the behavior of Illacme socal, so it’s unclear how it differs from other millipedes, Lee tells Ratul Mangal of the Daily Californian. But this discovery emphasizes that subterranean animals represent “the next frontier of discovery,” write the researchers in the study. The millipedes are currently threatened by human settlement and habitat loss, so their conservation is of “high importance,” they write. 

“Literally, these new species are right below our feet,” Derek Hennen, an entomologist with the Virginia Museum of Natural History who was not involved with the study, tells the L.A. Times. “This really drives home the point that it’s important to preserve these open green spaces and natural habitats as much as we can, because even in an intensely urbanized environment like Los Angeles, you can still find new species in places that people may have just not been looking before.”

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