Biologists report in the Proceedings of the National Academy of Sciences this week that they were unable to find  a pair of previously common Guatemalan salamander species -- Pseudoeurycea brunnata and Pseudoeurycea goebeli -- and  say they are apparently extinct. Numerous other species in Guatemala and Mexico also failed to turn up during several surveys – and others could only be found in the highest mountain elevations.

Lead study author David Wake, an integrative biology professor at the University of California-Berkeley, blames the climb to higher elevations for the salamanders' declines. "We think global warming is a factor, pushing organisms up to higher elevations where the habitat is wrong for them," he  said in a statement.

According to Wake, populations of other species that depend upon salamanders as food are also shrinking.

Wake did not find evidence of Chytrid fungus, which is responsible for killing off frog and other amphibian species worldwide. But  Karen Lips, a biologist at the University of Maryland, College Park, told National Geographic that the salamanders' disappearance has all the markings of the fungal infection, which infects amphibians' skin and interferes with their ability to absorb water and oxygen. First observed 10 years ago, the fungus has since spread to every continent with amphibian populations, and has been blamed for the deaths of millions of frogs worldwide.

Meanwhile, two endangered salamander species in the U.S. got a boost this week, as the U.S. Fish & Wildlife Service established 22,970 acres of critical habitat for the frosted flatwoods salamander (Ambystoma cingulatum), and 4,453 acres for the reticulated flatwoods salamander (Ambystoma bishopi). Previously believed to be a single species, the flatwoods salamander in 1999 was listed as threatened and protected under the Endangered Species Act The reticulated salamander will retain that status, while the frosted salamander will now be listed as endangered, a status level that will offer it greater protections.

The International Union for Conservation of Nature and Natural Resources' Red List of Threatened Species includes 484 species of endangered salamanders. Almost all of them are identified with a population trend of "declining."

Image: Pseudoeurycea goebeli, Sean M. Rovito/UC Berkeley