The new species, a blind pseudoscorpion called Parobisium yosemite, waits for prey with its venom-filled claws at the ready.
(The Yosemite Cave Pseudoscorpion; Credit for images: Texas Tech University)
(Close-up of the venom gland)
The good news for park visitors is that the arachnid is just half an inch in length with legs outstretched, so it poses little threat to humans or any other animals larger than an eighth of an inch, says James Cokendolpher, a research scientist and assistant curator of invertebrates at The Museum of Texas Tech University.
Cokendolpher and Austin-based researcher Jean K. Krejca documented the new arachnid in the Sept. 30th Occasional Papers. The new animal is commonly called the Yosemite cave pseudoscorpion.
Pseudoscorpions look like a cross between a spider and a scorpion, since they have a pear-shaped body, eight spidery legs and scorpion-like pincers.
Cokendolpher said this newly documented species was originally seen about three years ago.
“There was a team from Austin that was hired to go into some of the caves in Yosemite National Park to do a survey and map some of the caves,” he explained. “Jean was one of the first ones to discover the species. She and others caught two of them, which were sent to me for identification. Once we discovered it was a species unknown to science, they went back and collected in some other areas to see if the species was there.”
He believes this animal could be only the second cave-dwelling pseudoscorpion found in granite rockfall caves. Usually cave dwellers live surrounded by limestone, since these structures have more humidity and greater access to food, but this new animal evolved to make the best of its tough circumstances.
“This pseudoscorpion is as large as many of the other cave-dwelling species,” Cokendolpher said, explaining most of the more than 3,000 species of pseudoscorpions are much smaller. “Cave species are generally larger, have longer appendages, lighter coloration and are missing all the eyes. The canyon where it was found was made by a glacier during an ice age millions of years ago. Through time, rubble with larger rocks would fall and create piles with caves or subterranean voids. We think that’s where this animal was trapped and evolved into the species that it is now.”
(Inside the Yosemite granite cave)
To conserve energy, the pseudoscorpion spends most of its time chilling out.
“I kept a couple of them in the laboratory for quite a while,” he said. “They basically sat and did nothing for much of the time. We kept them in Petri dishes with plaster of Paris that was moistened so it was more like cave conditions. When we introduced other animals into the Petri dish it would go over and tap the animal. When it did that, it was able to sense chemical cues there such as identification, how large the item was and whether it was something suitable to eat.”
“Out of several weeks we kept them, the only thing that was eaten was a tiny spider,” he concluded. “Like many of other cave animals, it doesn’t need a lot of nourishment. That’s good for them in a food-poor environment.”
Cokendolpher shares the full story in this interview: