Highland Endemism: The Endangered Calumma hilleniusi of Madagascar’s Ankaratra Massif

Calumma hilleniusi (Brygoo, Blanc & Domergue, 1973) is a rare chameleon endemic to Madagascar's central highlands. Originally described as a subspecies of Calumma brevicornis, it was later elevated to full species rank. Its distribution is restricted to the Ankaratra Massif, where it inhabits montane forest and grassland between 1,550 and 2,550 meters above sea level. This high‑altitude range makes it one of the most specialized chameleons in Madagascar, adapted to misty, cool environments where few reptiles thrive. Morphologically, C. hilleniusi is distinguished by a relatively short rostral appendage, an elongated casque, and subtle coloration that blends with the upland vegetation. Females are oviparous, laying clutches of up to ten eggs.

The IUCN Red List currently classifies Calumma hilleniusi as Endangered, citing its extremely limited distribution, ongoing habitat degradation from deforestation and fire, and vulnerability to climate change. Its specialized ecology and narrow range make it highly susceptible to environmental shifts. The species name honors Dutch herpetologist Dick Hillenius.