Extremely rare discovery in Nevada’s Great Basin

Scientists identified three new toad species in Nevada’s Great Basin. The discovery is extremely rare as these are the first toad species to be identified in the US since 1985. 

On the bottom of an ancient lake, in Nevada‘s Great Basin, scientists found three new toad species. The discovery is extremely rare as the last time that new frog species were found in the U.S. was back in 1985 and the last discovery made north of Mexico was of the now extinct Wyoming toad, in 1968. The new toads were found in a small, wet habitat in the high-desert. This population, according to biologists, was separated form the others some 650,000 years ago.

“We’ve found the toads in small, wet habitats surrounded by high-desert completely cut off from other populations,” Dick Tracy, a renowned biology professor at the University of Nevada, Reno, and lead scientist on the project, said. “These are absolutely new, true species that have been separated from other populations for 650,000 years.”

The three new species, the Dixie Valley toad, Railroad Valley toad and Hot Creek toad are not connected geographically. They were found in Tracy’s 10-year long survey of the desert-dominated Great Basin. His team used 30 “shape” metrics and DNA studies to analyze these toads’ characteristics to determine if each were distinguishable from the closely related Western toad.

According to the evidence, these are indeed three distinct new species. The small new toads also have slightly different colours and they can grow up to about two inches long. Each have unique physical features, that makes them different form each other and other toads in the region.

“The Dixie Valley toad is a pretty toad, with flecks of gold on an olive background,” Tracy, a long-time professor in the biology department of the College of Science, said. “It’s not like the big, common green toads you might find in other marshes around the west or even in Rancho San Rafael Park in Reno.”

But as scientists were working to correctly identifying the new species, they also found that these new toads are already under threat. For example, the Dixie Valley toad is found in isolated spring-fed marshes adjacent to a proposed site for a geothermal power plant that could dry up their living environment.

“If this power plant goes in and the habitat is dried up, this recently discovered species could go extinct,” Tracy said. “It’s a good candidate for an Endangered Species Act listing. The ESA was passed under Richard Nixon in 1973, and the second species listed under the new Act was the Houston Toad. This is a tough conflict between commerce and biological resources, and we need to seek compromises so if the project proceeds, it won’t hurt the toads.”

The small isolated toad populations also have the smallest individuals compared to other western toads. The Dixie Valley species has the smallest body size among the region’s complex of related species in the western United States, and can be further diagnosed from other toads in the complex by the large glands on its hind legs in addition to its distinctive coloration.

With it’s current range severely restricted, suggesting that this species’ population is likely very small, the Dixie Valley toad is especially vulnerable to changes in environment.

“The toads are perfectly concealed in the dense vegetation of their habitat,” Gordon said. “You could easily miss seeing them during the day, making accurate counts difficult. But, during one trip at dusk, toads were everywhere, giving the impression that toads were locally abundant. And, without the water in this habitat, this toad species would completely disappear.”

According to the biologists, all three new species are natives of the Great Basin in Nevada, which was once covered by large marshes and giant inland lakes during the Pleistocene Epoch and is now among the most arid regions in the United States with only one percent of the landscape containing water.

“Our goal has been to understand the relationships among toad populations in the Great Basin,” Tracy said. “We’ve found that our knowledge of amphibian diversity in the western United States remains incomplete and that novel discoveries continue to occur, even in unlikely settings. This is really, really neat; an exciting thing, to find something not known to exist before.”

The discovery of the Dixie Valley toad was announced in the peer-reviewed science journal Zootaxa on July 6.