Researchers at the University of California, Davis have identified a new species of trapdoor spider, Aptostichus ramirezae, living beneath California's coastal sand dunes. Genetic analysis revealed it as distinct from the related Aptostichus simus, highlighting hidden biodiversity in familiar habitats. The discovery underscores threats to these fragile ecosystems from human and environmental pressures.
Scientists at the University of California, Davis have unveiled a previously unknown trapdoor spider species, Aptostichus ramirezae, inhabiting California's coastal sand dunes. This brown, quarter-sized arachnid, a secretive relative of tarantulas, spends its life in silk-lined underground burrows sealed by camouflaged, hinged doors. It ambushes prey by detecting surface vibrations, rarely venturing far from its home.
The findings, published in the journal Ecology and Evolution, stem from genomic DNA analysis of specimens once classified solely as Aptostichus simus. This species was thought to range widely from Moss Landing near Monterey southward to Baja California, Mexico—a broad distribution for such sedentary spiders. However, the study confirmed two genetically distinct, reproductively isolated populations, marking Aptostichus ramirezae as a cryptic species.
"While there are over 50,000 species of spiders worldwide, there are probably hundreds of thousands left to be discovered, even along the coast where new spider species may be hiding just underfoot of California beachgoers," said senior author Jason Bond, a professor in the UC Davis Department of Entomology and Nematology.
The new species honors Martina Giselle Ramirez, a pioneering arachnologist and dean at California State University, Stanislaus, known for her work on trapdoor spider genetics and support for underrepresented STEM students. Bond, who has named spiders after figures like Stephen Colbert and Barack Obama, chose this tribute for her contributions.
California now hosts four known trapdoor spider species exclusive to coastal dunes, including some on the Channel Islands. Yet, these habitats face severe threats from development, erosion, wildfires, and rising sea levels. "They're definitely at risk, especially the lineage Aptostichus simus," said corresponding author Emma Jochim, a UC Davis doctoral student. Aptostichus simus is now largely confined to San Diego, where sea-level projections are dire, limiting the spiders' ability to adapt.
Clarifying genetic distinctions aids conservation by pinpointing vulnerable populations. As Jochim noted, understanding biodiversity patterns is essential for prioritizing protection efforts. The research, supported by the National Science Foundation, involved contributors James Starrett and Hanna R. Briggs from UC Davis.