Scientists identify a new species of spider that lives underground in coastal sand dunes.

A new spider has been discovered crawling around coastal sand dunes from Moss Landing to Baja California, Mexico. Aptostichus ramirezae is a type of trapdoor spider – a chunky, hairy, brown spider roughly the size of a quarter. They are small and elusive relatives to tarantulas; this species is one of four known trapdoor spiders in California living exclusively in coastal dune habitats.

The females spend their life burrowed underground with a camouflaged (and hinged) door, emerging only in pursuit of prey when they feel the ground vibrating above.

A study published by UC Davis Department of Entomology and Nematology revealed that what was thought to be just one species of spider was actually two; the new spider is found to be a close relative of Aptostichus simus. While the two are nearly impossible to tell apart based on morphology alone, an analysis of genetic testing revealed separate lineages and genetic groups.

In science, the nuance matters. Both species, while found in similar habitats, have different distributions and are reproductively isolated – variables that can make certain species vulnerable. Understanding the genetic differences provide scientists with insight into which populations need protection most.

“They’re definitely at risk, especially the lineage A. simus,” said Emma Jochim, an author of the study, in an announcement. “The new species has a much wider range, but A. simus is now really only found in San Diego, and projections for sea-level rise in that area are very grim. These spiders are not really able to adapt that quickly to new habitats.”