In world of amphibians, a rare bright spot

More striking, however, is that their colors vary depending on the sex, which is also unusual for this kind of amphibian. The scientists found black females and orange, reddish and gray males.

"Other variations do exist between male and female amphibians, but color is not common because it's a group that's quite nocturnal and normally doesn't tend to show different coloration between gender. However, this species does," Chavez said. "That's particular, very striking and highly interesting to investigate."

The Zootaxa editors needed convincing that the males and females did not actually belong to different species. Chavez sought help from UCR biologist Alejandro Leal and his assistant Alejandra Mora, who carried out genetic testing and were able to verify that the males and females belonged to the same species. They also found the species are genetically closer to West Indies frogs than to those on the continent.

Chavez recalled another indigenous amphibian with gender color differences: the golden toad. Mention of this toad — once abundant in north-central Costa Rica's Monteverde Cloud Forest Reserve — strikes a sore spot for herpetologists, since 20 years have passed since its last appearance.

And the golden toad isn't alone. Nearly one-third of the world's amphibian species are globally threatened or extinct, according to the IUCN Red List. The organization assessed about 6,260 amphibians for the list. Scientists believe there are numerous culprits, including humans' encroachment on amphibian habitats, pollution, climate change and virulent fungi — amphibians are considered important indicators of biodiversity trends and environmental threats that may ultimately affect other wildlife.

In Costa Rica — which is home to 5 percent of the world's biodiversity and 186 of the planet's amphibian species — the fate of frogs is a major preocupation among environmental scientists. In 1999, scientist Alan Pounds wrote in the journal Nature that the populations of 20 to 50 frog and toad species in a 30-square-kilometer area of study in Costa Rica had quickly crashed. Last year, the Costa Rican Holdridge's Toad went extinct, according to the Red List.

However, the IUCN is not quick to place a species into the extinction category — sometimes, long-absent creatures jump back onto the scene. This occurred last May, when a team from the U.K.'s Manchester University and Chester Zoo happened upon a rare tiny female tree frog in the Costa Rican jungle, a cause for cheer (as seen in this BBC video).

With all the bad conservation news, it's worth pausing over discovered, or rediscovered, species. But even these good times can be fleeting. "It's not (always) good news," Chavez said, mentioning another recent discovery of a type of Costa Rican atelopus toad that appeared and then disappeared without a trace. "We're describing a species that we're almost sure doesn't exists (any more). We've visited the area in which it was discovered and it's no longer there. We're giving it a posthumous description."

More GlobalPost dispatches on Costa Rica:

The sloths of Costa Rica

The rice and beans war

Why you won't see Costa Rican shrimp on US menus

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