"When you go to these places that are so unexplored and so remote, we do tend to find new species ... but most of them are insects," Alonso said by telephone from Suriname's capital, Paramaribo. "What's really exciting here is we found a lot of new species of frogs and fish as well."

The two-tone frog -- whose skin is covered with irregular fluorescent lavender loops on a background of aubergine -- was discovered in 2006 as part of a survey of Suriname's Nassau plateau, the conservation group said.

Scientists combing Suriname's Nassau plateau and Lely Mountains found four other new frog species aside from the purple one, six species of fish, 12 dung beetles and a new ant species, the organization said in a statement.

These creatures were discovered by 13 scientists who explored a region about 80 miles (130 km) southeast of Paramaribo, including areas with enough clean fresh water sources to support abundant fish and amphibians.

They also found 27 species native to the Guayana Shield region, which spreads over Suriname, Guyana, French Guiana and northern Brazil. One of these was the rare armored catfish, which conservationists feared was extinct because gold miners had contaminated a creek where it was last seen 50 years ago.

Including the new species, the scientists observed 467 species at the two sites, ranging from large cats like panthers and pumas, to monkeys, reptiles, bats and insects.

While these places are far from human civilization, they are totally unprotected and may be threatened by illegal gold-mining, Alonso said.

These highland areas have also been investigated as sources of bauxite, used to make aluminum, but will most likely not be mined in the future, she said, at least not by the two mining companies that sponsored the study.

The sponsors are BHP Billiton Maatschappij Suriname (BMS, a subsidiary of BHP Billiton) Suriname Aluminium Company LLC (Suralco, a subsidiary of Alcoa Inc).