It has all the characteristics of a chameleon … but it fits on the tip of a finger. Scientists have discovered the world’s smallest adult reptile in Madagascar, according to a recently published study.
“We discovered it in the mountains north of Madagascar”, told AFP Frank Glaw, head of herpetology at the Zoologische Staatssammlung in Munich (Germany). A team of German and Malagasy scientists found two specimens during an expedition in 2012, but it was not known that they were adult individuals, he said.
The male “Brookesia nana” is the smallest adult reptile in the world with just 13.5 millimeters from the muzzle to the base of the tail – the size of a peanut -, and 22.5 mm including the tail. The hemipenis (sexual organ) of Brookesia nana is very large in proportion to its size. It measures 2.5 millimeters, or 18.5% of the length of the animal.
The female is significantly larger than the male, with 19.2 millimeters from the muzzle to the base of the tail, and 28.9 millimeters including the tail, details Frank Glaw in the review Scientific Reports (link in English). These two specimens remain the only ones discovered for this species.
“There are many very small vertebrates in Madagascar, including the world’s smallest monkeys and some of the tiniest frogs.”, added Andolalao Rakotoarison, from the University of Antananarivo in Madagascar, co-author of the study.
The discovered micro-chameleons, however, are not the product of “island dwarfism”, this phenomenon whereby species on an island, similar to their continental ancestor, evolve over time by reducing their size, under the pressure of several factors. “We have no explanation for the reasons for the size” Brookesia nana, says Franck Glaw.
The animal lives in a mountainous region, at an altitude of 1,300 meters.
Barely discovered, the Brookesia nana is already considered endangered, adds the scientist. “Habitat destruction poses the greatest threat to amphibians and reptiles in Madagascar”, explains the German scientist. Madagascar conceals treasures of biodiversity, but it is also one of the poorest countries in the world and its fauna and flora are not sufficiently protected.