Brookesia nana, also known as the nano-chameleon, is a species of chameleon that is endemic to montane rainforest in northern Madagascar.  It was described in 2021, and it could be the world's smallest reptile.  It is a blotchy brown color and the adult male measures just 22 mm in total length, and the female 29 mm in total length.   Unlike most other chameleons, Brookesia nana does not change colors and does not live in trees in the forest, but prefers the forest floor. Like other Brookesia species, females are generally larger than the males. It is a mystery why it is so small when other vertebrates grow as they mature. 
The species was discovered by herpetologist Frank Glaw and other German researchers in 2012  in the rainforest on the Sorata massif in northern Madagascar. It is likely that the species is endangered due to deforestation in Madagascar. 
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- Glaw, Frank; Köhler, Jörn; Hawlitschek, Oliver; Ratsoavina, Fanomezana M.; Rakotoarison, Andolalao; Scherz, Mark D. & Vences, Miguel (28 January 2021). "Extreme miniaturization of a new amniote vertebrate and insights into the evolution of genital size in chameleons". Scientific Reports. 11 (1): 2522. doi: 10.1038/s41598-020-80955-1. PMC 7844282. PMID 33510189.
- Bittel, Jason (1 February 2021). "New chameleon species may be world's smallest reptile". National Geographic. Retrieved 2 February 2021.
- "'Smallest reptile on earth' discovered in Madagascar". BBC News. 5 February 2021. Retrieved 5 February 2021.
- Andrew, Scottie (3 February 2021). "A newly discovered chameleon less than an inch long could be the world's smallest reptile". CNN. Retrieved 2021-02-04.