Saddleback toad

The saddleback toads are a genus of small, colourful toads the family Brachycephalidae /ˈbrækᵻsɛˈfælᵻdiː/ in the order Anura. As traditionally defined, the family is often limited to just one genus, Brachycephalus, but it is closely related to Ischnocnema, which therefore is placed in the family in recent treatments. Brachycephalus species are tiny, often yellow frogs that are native to Atlantic Forest in southeastern Brazil. In at least one species, B. ephippium, the bright colours are aposematic, warning potential predators of its toxicity, specifically tetrodotoxin.

Brachycephalus species are very small frogs, up to 1.8 cm (0.71 in) in length (mostly around 1 cm or 0.39 in), and include the smallest frog in the Southern Hemisphere, Izecksohn's toad (Brachycephalus didactylus). They have only three toes on each foot, and two fingers on each hand. This is in contrast to the usual five toes and four fingers of most frogs.

Brachycephalus species are active during the day, and live in the leaf litter on forest floors. The eggs undergo direct development, hatching into miniature frogs, without a tadpole stage. The eggs are laid on the ground, and covered in soil to protect them from the heat and predators. Their amplexus method is unusual, in that it begins with inguinal amplexus, with the male holding the female around the waist, and then shifts to axillary amplexus, in which the male grips above the female's arms. Most frogs species only use one technique.

Reported May 2015, seven new species have been discovered in Brazil's Atlantic rain forest in the states of Paraná and Santa Catarina, in southern Brazil. Most species of Brachycephalus are only found on one, or a few, mountaintops in the Brazilian cloud forests. These species tend to be isolated on the mountaintops, by valleys with habitat and temperatures, not suited to the frogs, which the frogs cannot cross, forming isolated populations of the species on sky island mountaintops.

The first Brachycephalus species was identified in 1824, but most of the frog species were discovered since the year 2000. The discovery of new frog species is difficult. Field work requires climbing steep mountain trails to the sites where the frogs live.

The frogs are restricted to cloud forests on one or a few nearby mountaintops, making the frogs vulnerable to extinction. Cloud forests are sensitive to climate changes and face threats from deforestation for pine tree plantations and cattle ranching.