Brookesia micra

Brookesia micra is a species of dwarf chameleon native to Madagascar, notable for being one of the smallest reptiles in the world. This tiny species belongs to the family Chamaeleonidae and was formally described in 2012 by Frank Glaw, Jörn Köhler, Ted Townsend, and Miguel Vences. Its discovery captured global attention due to its remarkably minute size and its significance in understanding evolutionary miniaturisation among vertebrates.

Taxonomy and Classification

• Kingdom: Animalia
• Phylum: Chordata
• Class: Reptilia
• Order: Squamata
• Family: Chamaeleonidae
• Genus: Brookesia
• Species: Brookesia micra

The Brookesia genus, commonly referred to as leaf chameleons, comprises small, ground-dwelling species found mainly in Madagascar’s forest ecosystems. Brookesia micra is among the most extreme examples of miniaturisation within this group.

Discovery and Habitat

Brookesia micra was discovered during field surveys conducted on Nosy Hara, a small limestone island off the northern coast of Madagascar. The island is part of the Nosy Hara Archipelago, known for its karstic landscape and high biodiversity.
The species inhabits dry leaf litter and forest floors, where it blends in perfectly with its surroundings due to its brownish colouration and leaf-like appearance. It is a terrestrial species, unlike many other chameleons that live in trees. During the day, it remains camouflaged among fallen leaves, and at night, it often climbs small twigs or grass blades to sleep, possibly to avoid predators.

Physical Characteristics

Brookesia micra holds the distinction of being one of the smallest known vertebrates.

• Adult Size:
  • Males measure around 13.5 mm (0.53 inches) from snout to vent and about 22 mm (0.87 inches) in total length including the tail.
  • Females are slightly larger, reaching around 19 mm (0.75 inches) in snout–vent length.
• Colouration: Typically brown to greyish, aiding in camouflage among dried leaves.
• Morphology: Like other chameleons, it has a laterally compressed body, independently movable eyes, and a prehensile tail, though the tail is proportionally shorter than in larger species.
• Sexual Dimorphism: Males are smaller and have distinct genital structures that help distinguish them from females.

Despite its small size, Brookesia micra exhibits the classic features of chameleons—projectile tongue, independent eye movement, and colour variation (though limited compared to arboreal species).

Behaviour and Ecology

This tiny chameleon displays fascinating behavioural adaptations suited to its miniature habitat:

• Diet: It feeds on minute invertebrates such as springtails, mites, and tiny insects found in the leaf litter.
• Activity: Diurnal, spending daylight hours in leaf litter and climbing low vegetation at night.
• Reproduction: Very little is known about its breeding habits, but like other Brookesia species, females are believed to lay a few small eggs in concealed spots within the forest floor.
• Predation: Its primary defence mechanism is camouflage; its resemblance to bits of leaf litter provides excellent protection from predators.

Evolutionary Significance

Brookesia micra represents an extreme example of island dwarfism, a phenomenon where species evolve smaller body sizes when isolated in restricted habitats such as islands. The species’ restricted range and miniature size make it an ideal case study for evolutionary biologists exploring constraints on vertebrate body size and ecological adaptation.
Scientists suggest that the miniaturisation of Brookesia micra is linked to the limited ecological niches available on the small island of Nosy Hara. Similar evolutionary trends have been observed in other reptiles, amphibians, and mammals on isolated islands.

Conservation Status

The International Union for Conservation of Nature (IUCN) lists Brookesia micra as Endangered due to its extremely restricted distribution and the potential threats to its habitat. Although Nosy Hara is a protected area within the Nosy Hara National Park, the island’s ecosystems remain vulnerable to:

• Habitat degradation from deforestation and vegetation clearance.
• Tourism-related disturbances and potential habitat alteration.
• Climate change, which may affect temperature and moisture levels critical for microhabitat survival.

Because Brookesia micra occupies a very narrow ecological niche, even minor environmental changes could have severe impacts on its survival.

Importance in Scientific Research

The discovery of Brookesia micra has contributed significantly to herpetology and evolutionary biology. It highlights:

• The remarkable biodiversity of Madagascar, one of the world’s leading centres of endemism.
• The importance of microhabitats in sustaining unique life forms.
• The evolutionary limits of vertebrate body size, sparking debates on the physiological and ecological constraints of miniaturisation.

The study of Brookesia micra also emphasises the need for continued exploration of Madagascar’s smaller islands, which may harbour more undiscovered microfaunal species.

Related Species

The genus Brookesia includes several other diminutive chameleon species, many of which are also endemic to Madagascar, such as:

• Brookesia minima – previously regarded as the smallest chameleon before B. micra’s discovery.
• Brookesia tuberculata – slightly larger, found in northern Madagascar.
• Brookesia desperata and Brookesia tristis – both described alongside B. micra and named to highlight conservation concerns (“desperate” and “sad,” respectively).