Discovery of new cave millipedes casts light on Arizona cave ecology

J. Judson Wynne, with the Department of Biological Sciences at NAU and cave research scientist with the U.S. Geological Survey's Southwest Biological Center, and Kyle Voyles, Arizona State Cave Coordinator for the Bureau of Land Management, collected specimens leading to the discovery of two new millipede species in caves on opposite sides of the Grand Canyon.

Wynne and Voyles, known for their cave research, also discovered a new genus of cricket last spring.

“We knew the millipedes likely represented two distinct species because the two populations were separated by the Grand Canyon,” Wynne said. “The fact these two species belong to an entirely new genus was a great surprise to us.”

Wynne said these eyeless albino millipedes are “essentially living fossils” and provide researchers with another piece of the puzzle needed to better understand cave ecosystems.

He explained that during the last Ice Age, when northern Arizona was warmer and wetter, millipedes lived in leaf litter. As the climate warmed, they sought refuge in caves, where the subterranean realm provides more constant climatic conditions enabling their survival.

Representing two distinct species (one occurring in one cave on the South Rim, the other in two caves on the North Rim of Grand Canyon), this new genus of cave-limited millipede has been confirmed by Bill Shear, a leading millipede expert at Hampden-Sydney College in Virginia.

“Western U.S. caves have not been at all well explored for examples of cave life” Shear said. “We can expect more new species from the ongoing work at Northern Arizona University.”

This new genus was confirmed by analysis of the eighth pair of legs (or gonopods) on the male specimens.

For the north rim species, Voyles explained that the discovery will result in the two caves becoming listed as 'significant' under the Federal Cave Resource Protection Act of 1988.

Voyles indicates there are a lot more exciting discoveries to be made. “With 170 known caves [on the BLM Arizona Strip lands], there is no doubt that there is more to find. The research we have conducted here is just the tip of the proverbial iceberg,” he said.

He added that this also means more work for resource managers, who will now have to pay much closer attention to the use and conservation of these caves and their biological attributes.

Neil Cobb, curator of the Colorado Plateau Museum of Arthropod Biodiversity in the Department of Biological Sciences at NAU, said, “Caves are extreme habitats that have received far too little attention. The arthropods that can survive these dark and resource-poor environments can tell us a lot about what makes them so successful as a group.”

While conducting ecological inventories of 30 caves on the Colorado Plateau of northern Arizona, research by Wynne and Voyles has resulted in the discovery of at least 10 new species, including a new species of spider, a new genus of cave cricket (Family Rhaphidophoridae), possibly two new cricket species, a new barklouse (Psocoptera) species, a new beetle species, and possibly two new springtail species (Collembola). With many of the collected specimens still awaiting identification by taxonomists, the researchers believe additional species discoveries are likely.

The new millipede genus will be named in honor of NAU ecologist, John Prather, who died last year.

Wynne, also an associate curator with the Colorado Plateau Museum of Arthropod Biodiversity, is also developing methods to detect caves using thermal remote sensing imagery. Once procedures are developed, these techniques ultimately will be used to find caves on Mars.

Voyles is also the cave resource management lead for Grand Canyon-Parashant National Monument. His work has led to the development of cave resource management plans and the ultimate protection of numerous caves in northwestern Arizona and southwestern Utah.