A new chameleon known as Brookesia nana, or the nano-chameleon has been discovered in northern Madagascar. Two specimens a male and a female – of what is probably the smallest reptile in the world were discovered by scientists. The female is 19 mm (0.7 in) or 29 mm (1.1 in) including the tail, and the male is just 13.5 mm (0.5 in) long, or 22 mm (0.9 in) including the tail; the smalles male of any vertebrate, enough to sit on a human fingertip. Both were adults and the female had two eggs inside her. The male may be smaller than the email but its genitalia are quite large compared to its body – almost 20% its body size.
The genus Brookesia consists of mostly terrestrial species divided into two major lineages that diverged 40-50 million-years-ago. One lineage contains larger species, while the other has only miniaterized species like the Brookesia nana. The miniaterized Brookesia are mostly rainforest species inhabiting mostly lowland, with very smalles ranges and only few species are known from more than two locations.
The previously smallest specimen was a male of B. micra with 15.3 mm (22.2 mm with tail).
The study has been published in Scientific Reports: (Glaw, F., Köhler, J., Hawlitschek, O. et al. Extreme miniaturization of a new amniote vertebrate and insights into the evolution of genital size in chameleons. Sci Rep 11, 2522 (2021). https://doi.org/10.1038/s41598-020-80955-1)