A team of researchers led by University of Nevada Professor C. Richard (Dick) Tracy has discovered three new toad species in the Great Basin region of northern Nevada.
The Dixie Valley toad (Bufo williamsi). Image credit: Mike Wolterbeek, University of Nevada, Reno.
The three new species are the Dixie Valley toad (Bufo williamsi), the Railroad Valley toad and the Hot Creek toad.
They are small in size, yet each have a suite of unique physical features that differ from each other, as well as other toads in the region.
Each of the species has slightly different colors, and they are about 2 inches long when full grown.
All three new species were detected through genetic analyses of toad populations sampled throughout Nevada’s Great Basin, 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 U.S. with only 1% of the landscape containing water.
“We’ve found the toads in small, wet habitats surrounded by high-desert completely cut off from other populations,” Professor Tracy said.
“These are absolutely new, true species that have been separated from other populations for 650,000 years.”
The Railroad Valley toad is found in the Tonopah Basin in the central Nevada desert.
The Hot Creek toad lives about 35 miles away but in Hot Creek Mountain Range, in a drainage isolated from the Railroad Valley toad.
The Dixie Valley toad (Bufo williamsi). Image credit: Mike Wolterbeek, University of Nevada, Reno.
The Dixie Valley toad is restricted to the spring fed-wetland habitat along the western edge of the Dixie Valley playa.
This species has the smallest body size among the region’s complex of related species in the western U.S., 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.
“The Dixie Valley toad is a pretty toad, with flecks of gold on an olive background,” Professor Tracy 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.”
The Dixie Valley toad is typically nocturnal, emerging at dusk, and can be found in moist vegetation or in very still, shallow water with very little vegetation canopy.
In autumn, it is likely that this species retreats to burrows to hibernate, emerging in spring to breed. Breeding occurs from March to June.
The overall population numbers of the Dixie Valley toad are unknown. The habitat occupied by the species is adjacent to a proposed site for a geothermal power plant that could dry up the marsh and threaten the toad’s survival.
The discovery of the Dixie Valley toad is outlined in a paper published in the July 6, 2017 issue of the journal Zootaxa.
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Michelle R. Gordon et al. 2017. A diamond in the rough desert shrublands of the Great Basin in the Western United States: A new cryptic toad species (Amphibia: Bufonidae: Bufo (Anaxyrus)) discovered in Northern Nevada. Zootaxa 4290 (1); doi: 10.11646/zootaxa.4290.1.7
