Only 16 millimeters long, Sphaerodactylus ariasae is now ranked as the smallest of all 23,000 bird, reptile and mammal species.
The researchers ventured to the island of Beata in search of new species in 1998. They discovered the tiny lizards living in a sink hole and cave within a national park. Now, they have finally found the scientific description of the animal nearly four years later.
Though the finding is remarkable, the researchers say they weren't surprised to locate it there. The smallest and largest species of animals tend to found on islands, they said. That's because species are able to evolve to fill ecological niches in isolated island environments.
The newly discovered lizard is so small that it approaches the physiological limit for all reptiles, birds and mammals. The smaller the lizard gets, the larger its surfaces area becomes as a percentage of its body mass. With such a large surface area, the species is in constant danger of losing too much water and drying up.
"If we don't provide a moist environment when we collect them, they rapidly shrivel right up and die by evaporation from the proportionally large area of their surface," said Blair Hedges an evolutionary biologist at Pennsylvania State University and co-discoverer of the new lizard with Richard Thomas of the University of Puerto Rico.
Even though Hedges regularly finds new species in the course of his work as an evolutionary biologist, he's still amazed by the new discovery. "It really highlights how little we know of the biodiversity of the tropics in general and of places not even that far from the United States," he said. The island of Beata is closer to Miami than Miami is to Puerto Rico yet it still may host a number of new species.
"The discovery of yet another micro-vertebrate in the Caribbean underscores the fact that this small part of the world harbors many of the world's most distinctive species," said Michael Smith senior research fellow with the Center for Applied Biodiversity Science at Conservation International.
"The Caribbean islands are home to the world's smallest bird, the smallest frog, the smallest snake, and now the smallest lizard. No other part of the world has so many extreme vertebrate species at either end of the size scale," he said.
Because many animals have yet to be identified, the researchers believe nations and scientists need to employ a more aggressive effort to find them before destruction of the species' habitat reduces biodiversity.
"We need desperately to find out what's there in order to protect it," said Hedges.
As deforestation rapidly destroys biodiversity in the Caribbean region, discoveries like this one are all the more important, said Smith.
"It's hard to know what we've lost, or what is at stake, at the smaller end of the size scale. The first step in taking care of biodiversity is to know what we've got. That's why the explorations by scientists like Hedges and Thomas contribute so much to conservation," said Smith.
(Reported by Koren Capozza in Los Angeles)