Striking New Tarantula Species Discovered ‘in Our Own Backyard’ in Arizona

A brand new species of tarantula has been discovered lurking in southeastern Arizona.
The new species, Aphonopelma jacobii, is black and gray with bright red hair on its abdomen. It was found deep in the forests atop the Chiricahua Mountains, according to a new paper in the journal ZooKeys.
Researchers from the University of Idaho were thrilled and surprised to discover this new species in “our own backyard.”
“We often hear about new species being discovered from remote corners of Earth, but it is remarkable that these spiders are found in our own backyard, albeit in somewhat difficult-to-access areas of our backyard,” study co-author Chris Hamilton, assistant professor at the University of Idaho, said in a statement.
“With Earth in the midst of a human-mediated extinction crisis, it is astonishing how little we know about our planet’s biodiversity, even for conspicuous and charismatic groups such as tarantulas.”
This critter lives at high altitudes in the mountains, surviving long cold winters, particularly in the Madrean “Sky Islands” (MSI), which are forested mountain ranges between the Colorado Plateau and the Rocky Mountains in the southwestern United States and the Sierra Madre Occidental in northwestern Mexico. These mountain ranges—including the Chiricahua Mountains—are separated by low-level grasslands and deserts, meaning the species atop each range have evolved in relative isolation.
“As part of the Madrean Archipelago, woodland and forest habitats in the Chiricahua Mountains are physically isolated from those of other MSI ranges, leading to the evolution of numerous short-range endemic species that are restricted to them. Taken together, these mountains are part of the Madrean pine-oak woodlands biodiversity hotspot and are among the most biodiverse regions in the United States, so it is no surprise that tarantulas show similar patterns of high diversity,” the researchers wrote in the paper.
Scientists previously thought each range was home to only a single species of tarantula. However, this was changed by the discovery of Aphonopelma jacobii, as the Chiricahua Mountains were already known to be home to another species, A. chiricahua.
“The discovery of A. jacobii sp. nov. in the Chiricahua Mountains is exciting and noteworthy because it documents the first known case of multiple short-range endemic tarantula species inhabiting a single MSI range,” the researchers wrote.
“This marks the first documented case of syntopy between two montane endemics in the Madrean Archipelago and adds to our knowledge of this threatened region’s unmatched tarantula diversity in the United States.”
Climate change threatens the habitat of this new species. Researchers worry that the forests of the MSI region will decrease in coverage of the mountains due to changes in temperature and rainfall. Species that have evolved to be specialized to these forested environments may, therefore, go extinct in the coming decades.
“These fragile habitats are also threatened by increased exurban development in the San Simon Valley and Portal areas, destructive recreational activities, and wildfires,” co-author Brent Hendrixson, a professor at Millsaps College, said in the statement.
“In addition, there is some concern that these tarantulas will be exploited for the exotic pet trade due to their rarity, striking coloration, and docile disposition. We must consider the impact that unethical collectors might have on these spiders when determining the threats to this species and the implications for its conservation.”
The new species was named after tarantula researcher Michael A. Jacobi, who helped study the spider specimens.
“This discovery represents the 30th species of tarantula documented from the United States. Aphonopelma is the most species diverse tarantula genus on the planet (at least for documented species). Our research adds to this number and continues to advance our understanding of the true species diversity in this incredibly interesting and important biodiversity hotspot,” Hamilton said.
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Hamilton, C. A., Hendrixson, B. E., & Bringas, K. S. (2024). Discovery of a new tarantula species from the Madrean Sky Islands and the first documented instance of syntopy between two montane endemics (Araneae, Theraphosidae, Aphonopelma): a case of prior mistaken identity. ZooKeys, 1210, 61–98. https://doi.org/10.3897/zookeys.1210.125318