The Brazilian gold frog (''Brachycephalus didactylus''), also known as Izecksohn's toad or flea-frog, is a very small species of frogs in the family

Brachycephalidae The Brachycephalidae () are a family of frogs confined to eastern and southern Brazil and northern Argentina. The family is composed of two externally quite different genera: the tiny, often (but not always) colourful and plump saddleback toads ...

. It is

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to southeastern

Brazil Brazil ( pt, Brasil; ), officially the Federative Republic of Brazil (Portuguese: ), is the largest country in both South America and Latin America. At and with over 217 million people, Brazil is the world's fifth-largest country by area ...

and is known from the central part of the state of

Rio de Janeiro Rio de Janeiro ( , , ; literally 'River of January'), or simply Rio, is the capital of the state of the same name, Brazil's third-most populous state, and the second-most populous city in Brazil, after São Paulo. Listed by the GaWC as a ...

and from Serra das Torres in extreme southern

Espírito Santo Espírito Santo (, , ; ) is a state in southeastern Brazil. Its capital is Vitória, and its largest city is Serra. With an extensive coastline, the state hosts some of the country's main ports, and its beaches are significant tourist attra ...

. All three English names are misleading or potentially confusing. Many species in the genus '' Brachycephalus'' are bright yellow-orange, hence the name "Brazilian gold frog", but ''B. didactylus'' is all brown. "Izecksohn's toad" leads to easy confusion with another species in the genus, '' B. izecksohni'', and both names refer to the herpetologist

Eugênio Izecksohn Eugênio Izecksohn (1932 – June 2013) was a Brazilian herpetologist.

. "Flea-frog" or "flea-toad" was historically restricted to ''B. didactylus'', once placed in its own genus ''Psyllophryne'' instead of ''Brachycephalus'', but a second species, '' B. hermogenesi'', was described in 1998 and two others, '' B. pulex'' and '' B. sulfuratus'', have been described since then, bringing it to four species of flea-frogs/toads.

Comparison with other small frog species

At in snout–to–

vent Vent or vents may refer to: Science and technology Biology *Vent, the cloaca region of an animal * Vent DNA polymerase, a thermostable DNA polymerase Geology *Hydrothermal vent, a fissure in a planet's surface from which geothermally heated wate ...

length, ''B. didactylus'' is one of the smallest frogs in the world. This species and the roughly similar-sized '' Eleutherodactylus iberia'' from Cuba were once regarded as ''the'' smallest, but several others that are smaller have since been discovered, including the closely related ''B. pulex'' at , '' Stumpffia contumelia'' from Madagascar at , and ''

Paedophryne amauensis ''Paedophryne amauensis'' is a species of microhylid frog endemic to eastern Papua New Guinea. At in snout-to-vent length, it is considered the world's smallest known vertebrate. (See also Ecological guild.) The species was listed in the '' ...

'' from New Guinea at . SmallestFrogComparison

References

Brachycephalus Endemic fauna of Brazil Amphibians of Brazil Amphibians described in 1971 Taxa named by Eugênio Izecksohn {{Brachycephaloidea-stub