New Species of Pseudoscorpion Found in Talus Caves in Yosemite National Park

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Date: October 21, 2010

Yosemite National Park was shaped by glacial erosion over the past several million years. As the last glacier retreated from what is now Yosemite Valley, it left behind iconic granite formations such as Half Dome and El Capitan. Since then, rocks have fallen, and continue to fall from the sheer 3,000 foot granite walls, creating talus slopes that line the walls of Yosemite Valley. These talus slopes help park officials learn about rockfall activity, but have also been found to be habitat for a new species of arachnid.

These talus slopes create caves of various sizes. Within two of these caves in Yosemite Valley, located in close proximity and possibly only a few hundred years old, Yosemite biologists have discovered a new species of pseudoscorpion, called the Yosemite Cave Pseudoscorpion (Parobisium yosemite).

A pseudoscorpion is a small arachnid that resembles a true scorpion, but does not possess a stinger or a tail. The tiny arachnid was found deep in passageways, at the end of light zones, among granite sand, granite rocks, and leaf litter and debris. They survive at an average temperature of 51 degrees Fahrenheit. The Yosemite Cave Pseudoscorpion is believed to prey upon mites, flies, small spiders, beetles, ants, and millipedes.

The arachnids are about the length of a fingernail. The pseudoscorpion has no posterior eyes and lacks the typical tapetum, the layer of reflective tissue that is present on the back of the eye. The Yosemite Cave Pseudoscorpion also presents an atypical color, which is a tan/amber coloring, with reddish-brown legs. The main differences between the cave-adapted Yosemite Cave Pseudoscorpion and other pseudoscorpions are related to their loss of eyes and their elongated palp, the pincer like feature on the front two legs of scorpions and pseudoscorpions.

“We are thrilled about the new discovery of this fascinating species. Yosemite National Park is one of the great laboratories of the natural world and finds like this are incredibly exciting. We will continue to study the pseudoscorpion, as well as look for other new species of flora and fauna,” said Dr. Niki Nicholas, Chief of Resources Management and Science, at Yosemite National Park.

The pseudoscorpion is known as a troglobite, a small cave-dwelling animal that has adapted to a dark environment. Such species typically include spiders, insects, and fish. Most troglobites live permanently underground and cannot survive outside of their cave environment. Sixteen other species of pseudoscorpion exist, all from the northern hemisphere, including from the United States, China, Japan, and South Korea.

Ongoing research on the Yosemite Cave Pseudoscorpion is being conducted to further understand this new species. This discovery will further inspire Yosemite biologists to explore regions of the park not traditionally sampled for new fauna. Additionally, biologists in Yosemite have made it a top priority to continue further research into the talus cave ecosystem and biology to learn more about these relatively unexplored areas.

The Yosemite Conservancy, the primary fundraising organization for the park, contributed vital funding for the important fieldwork that lead to the discovery of this new species in Yosemite National Park.

The exact location of the caves in which the pseudoscorpions were found is being withheld to protect the tiny cave-dwellers.

Last updated: March 1, 2015

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