Brachycephalus brunneus

## About

A Brachycephalus brunneus on a leaf.

***(Brachycephalus brunneus)*** is a species of tiny toadlet native to the Eastern coast of South America. B. brunneus is a small-bodied toadlet that has dark brown colouration and dark orange limbs. They have large, dark eyes that are common among toadlets. The species (and the genus it belongs to), is known for its inability to land after jumping. The reason for this has been attributed to the toadlet's ear canals, the vestibular system of which do not function regularly. In most species, the vestibular system is comprised of fluid-filled chambers in the inner ear, which when combined with fine hears, allows the body to maintain movement and the brain to recognise its positioning, in simpler terms, keeping the body balanced. A study that examined the vestibular systems of 147 frog and toad species concluded that; in B. brunneus, the vestibular system does not provide adequate information to the toadlet's brain as a result of low liquid contents, thereby influencing its landing and positioning whilst airborne. This inefficiency becomes also apparent while the toadlet is simply walking, moving with a wide, stomping and hobbling gait. B. brunneus' survivability should likely be degraded by this hindrance and the reason why the species has not died out has been attributed to possible defenses evolved by the toadlet, including toxicity, thick skin and enhanced camouflage. B. brunneus grows to only around 10-15mm (0.4-0.6in) long.

### Conservation Status

B. brunneus is threatened greatly by habitat degradation and agricultural encroachment. Deforestation for the cultivation of coffee, exotic trees and sugar cane, as well as the captivation of livestock such as cattle, have likely led to a decrease in the overall population of the species. B. brunneus is listed as data deficient by the IUCN however, AmphibiaWeb has stated that recent surveys have concluded the species be listed as least concern.

## Range and Population

B. brunneus inhabits only a small area of the Atlantic forest in Brazil. Here, it occurs only in cloud/montane forests and rainforests at elevations of 1,300-1,600m (4,265-5,249.3ft), living underneath thick vegetation and leaflitter. The species' population is currently unquantified however, it has been referred to as 'locally abundant'.

## Behaviour

Little is known about this toadlet's behaviour. It is known to be abundant under leaflitter and is likely diurnal. B. brunneus is most often sighted from December-February, but has also been observed from November-April. It likely produces directly developing offspring. Whilst jumping, B. brunneus will spread out its limbs in an outstretched position, which it will retain on landing. It may land on its rear, back, belly or even its face however, the impact does not seem to damage the toadlet in any way.

### Relationship with Humans

B. brunneus does not interact with humans outside of captive environments.

## In Captivity

B. brunneus is kept only in private zoological facilities and cannot be found in public zoos.

## Sources

* IUCN Red List of Threatened Species - https://www.iucnredlist.org/species/61746/12553521
* Brachycephalus brunneus | AmphibiaWeb - https://amphibiaweb.org/species/6541
* These Absurd Toadlets Are So Tiny, They Can't Balance Anymore, And The Footage Is Hilarious | Science Alert - https://www.sciencealert.com/these-absurd-frogs-are-so-tiny-they-ve-lost-all-ability-to-balance
* Tiny Brazilian frogs are poor jumpers because their ear canals are too small | Phys.Org - https://phys.org/news/2022-06-tiny-brazilian-frogs-poor-jumpers.html