Hidden beneath the leaf litter of a northern Malagasy forest lives a chameleon so slight that it could tumble off the tip of your finger. Measuring just under 30 millimeters from snout to tail, the newly described species, Brookesia nana, may be the smallest reptile on Earth, researchers report January 28 in Scientific Reports.
Just two adult specimens, a male and female, are known. The female measures 28.9 millimeters, considerably larger than the 21.6-millimeter-long male. The size difference may have driven the male’s genitalia to be quite large — nearly 20 percent of its body length — to be a better fit to his mate, herpetologist Frank Glaw of the Bavarian State Collection of Zoology in Munich and colleagues suggest.
Dubbed B. nana for its nano size, the species belongs to a genus of at least 13 other small chameleons spread out across the mountainous forests of northern Madagascar. Why B. nana and its cousins shrank to such minuscule proportions remains a mystery, though smallness does have its benefits: There’s some evidence that small chameleons are especially good shots with their ballistic tongues.
In daylight, Brookesia chameleons scour the forest floor, snatching up mites and other small invertebrates, Glaw’s team suspects. At night, the lizards retreat upward, gripping blades of grass or other plants for safety.
Deforestation and habitat degradation threaten B. nana’s future, the researchers say, though the region where the compact chameleons were found was recently designated a protected area by the Malagasy government. The species may soon be listed as critically endangered, the gravest rating made by the International Union for Conservation of Nature.
sciencenews.org, 4 February 2021