The male Brookesia nana just became the world's smallest-known reptile (Credit: Frank Glaw (SNSB / ZSM)

Madagascar, an island off the coast of Africa, is home to some of the world's most exciting and unique animal species — about 75 percent of which cannot be found anywhere else on the planet. These include the long-necked giraffe weevil, the colorful, cat-sized panther chameleon, and the bright orange-red tomato frog! The latest to join this impressive list of exotic creatures is a new reptile species small enough to perch on the tip of a finger!

The two adult specimens — a male and a female — of the Brookesia nana, or nano-chameleon, were discovered in Northern Madagascar's rainforests by an expedition team led by Dr. Frank Glaw, a herpetologist at the Bavarian State Collection of Zoology in Munich, Germany. The male nano-chameleon, which measured 13.5 mm (0.5 inches) from snout to vent — with a total length of 22 mm (0.87 inches) — is the smallest among all the world's 11,500 known reptile species. The title previously belonged to the Jaragua dwarf gecko, which boasts a slightly longer snout to vent length of 16 mm (0.63 inches). The female nano-chameleon was much larger in comparison to the male, measuring a "massive" 19.2 mm (0.75 inches) from snout to vent, with an overall length of 29 mm (1.14 inches).

"At first glance, we realized that it was an important discovery,” says Malagasy herpetologist Andolalao Rakotoarison, co-author of the study published in the Scientific Reports journal on January 28, 2021.

Unlike most other chameleons, the blotchy brown lizards do not change color. They also prefer to live on the rainforest floor, spending their days hunting for mites and springtails in the leaf litter, and their nights hiding in the tall grass blades.

The female adult nano-chameleon measures 19.2 mm (Credit: Frank Glaw (SNSB / ZSM)

The scientists are not sure how the species became so small. In most cases, miniature size is attributed to the “island effect,” where animals trapped on small islands tend to evolve smaller body sizes. However, the nano-chameleons were found in the high-altitude rainforests, which have ample space and natural resources for animals to flourish. "The reptiles' home at around 1,300 meters above sea level… is quite unusual for this group of miniaturized chameleons,” says Dr. Glaw.

The nano-chameleons' family tree further deepens the size mystery. “The closest relative of the new chameleon is also not the similarly tiny Brookesia micra, but instead the nearly twice as large B. karchei, which occurs in the same mountains,” said German herpetologist and study co-author, Jörn Köhler. “That shows that this extreme miniaturization has arisen convergently [or independently] in these chameleons.”

The researchers, who were unable to find any more nano-chameleon specimens, believe the reptiles' habitat is most likely limited to just a few acres. If right, it could place the lizards at the risk of extinction. “Unfortunately, the habitat of the nano-chameleon is under heavy pressure from deforestation, but the area has recently been designated as a protected area, and hopefully that will enable this tiny new chameleon to survive,” says evolutionary biologist and study co-author Oliver Hawlitschek.