DIVERSITY & ENDEMISM
Very little of the Atlantic Forest remains, and what does is highly fragmented. Despite this, it still maintains extremely high levels of diversity and endemism, and is one of the highest priorities for conservation action globally.
The Atlantic Forest has been floristically isolated from other South American tropical forests by the savannas and woodlands of the Cerrado for thousands of years, explaining the region's remarkably high plant endemism – of 20,000 vascular plant species occurring there, about 8,000 are endemic. Endemism in trees is particularly high, with more than half the species found nowhere else.
More than 450 tree species have been recorded in a single hectare of forest in southern Bahia. Two trees of great value in the timber industry are today very rare: Brazil-wood (Caesalpinia echinata) and Brazilian rosewood (Dalbergia nigra). Brazil-wood has been threatened since the early 19th century because of its value for furniture and musical instruments. Another endemic timber species, Paratecoma peroba, is approaching extinction in the region.
The Atlantic Forest has spectacular bird diversity, with over 930 species, about 15 percent of which are found nowhere else. There are 23 endemic genera. Because most of the region's forests have been cleared during 500 years of exploitation, many species are now threatened, and at least one is extinct in the wild, the Alagoas curassow (Crax mitu). The species was last sighted in the wild in 1987 and now exists only in a small captive population in Rio de Janeiro.
BirdLife International has identified four Endemic Bird Areas (EBAs) in the hotspot. The Atlantic Forest Lowlands is arguably the most exceptional, with more than 50 species and 10 genera confined to this EBA. It extends from southern Bahia along the coast to Rio Grande do Sul in Brazil, and including part of Paraguay and Argentina.
There are many unusual birds in the Atlantic Forest. They include the red-billed curassow (Crax blumenbachii, EN), which has its last stronghold in the Sooretama Biological Reserve in the state of Espirito Santo, and the rare Brazilian merganser (Mergus octosetaceus, CR), a flagship for the southern Atlantic Forest in Brazil and Misiones. There are also a number of threatened parrots, such as the red-tailed Amazon (Amazona brasiliensis, VU) and the red-browed Amazon (Amazona rhodocorytha, EN).
Murici Ecological Station (61 km²) in the state of Alagoas, and Frei Caneca Private Reserve (6,3 km²) in the state of Pernambuco in northeastern Brazil, protect forests fragments that are now the last stronghold for a number of threatened species. They include the Alagoas foliage-gleaner (Philydor noveasi, CR) and the Alagoas antwren (Myrmotherula snowi, CR).
More than 70 mammals, of a total of over 260 species occurring, are endemic to the Atlantic Forest. They include interesting species such as the thin-spined porcupine (Chaetomys subspinosus, VU) and painted tree rat or cacao rat (Callistomys pictus), which represent monotypic genera, and the maned sloth (Bradypus torquatus, EN), a larger relative of the widespread three-toed sloths (B. tridactylus and B. variegatus). One particularly notable endemic is the Brazilian arboreal mouse (Rhagomys rufescens, CR), one of the rarest of the South American mammals. Originally described from a single specimen collected in the state of Rio de Janeiro in the 19th century, a second specimen was only recently discovered in Viçosa in Minas Gerais.
Twelve mammal genera are endemic, including two primate genera that are flagships for the conservation of the Atlantic Forest – the lion tamarins (Leontopithecus spp.), with four species, one of which was discovered only in 1990 on the coast of northern Paraná, and the two species of muriqui (Brachyteles spp.), the largest of the New World primates. All six species are Endangered or Critically Endangered. Of the 14 species of primate endemic to the Atlantic Forest, nine are either Critically Endangered or Endangered, and a further two species are Vulnerable.
Of the more than 300 reptile species occurring in this hotspot, approximately 95 species, and eight genera, are endemic. About half of the nearly 20 species of Bothrops snakes present are endemic. Threatened reptiles in the region include the golden lancehead (Bothrops insularis, CR), endemic to the Ilha Queimada off the coast of São Paulo, the Brazilian snake-necked turtle (Hydromedusa maximiliani, VU) from the states of Espírito Santo, Minas Gerais, Rio de Janeiro, and São Paulo, and Hoge's sideneck turtle (Phrynops hogei, EN), which ranges from the Rio Itapemirim basin to the Rio Paraíba basin in southeastern Brazil.
Five of the world's marine turtle species are known from Brazilian waters: the loggerhead (Caretta caretta, EN), green (Chelonia mydas, EN), hawksbill (Eretmochelys imbricata, CR), leatherback (Dermochelys coriacea, CR), and olive ridley (Lepidochelys olivacea, EN). The Abrolhos reefs, off the coast of southern Bahia, are important feeding grounds for the first three. Throughout Brazil, sea turtles are threatened by hunting, egg collection, and the destruction of critical nesting habitat on the area's beaches.
Amphibian diversity is very high, with more than 450 species recorded, more than half of which are endemic. Fifteen genera, and one entire family – the Brachycephalidae, with six species of the genus Brachycephalus – are endemic. Examples of the many threatened species in this hotspot include three that are Critically Endangered and known from single localities: Phyllomedusa ayeaye, from Poços de Caldas in the state of Minas Gerais; Scinax alcatraz, from the Ilha de Alcatrazes in the state of São Paulo; and Hyla cymbalum, from Grande da Serra in the state of São Paulo (and which has not been recorded during recent surveys and may be extinct).
There are at least 350 fishes known from the Atlantic Forest streams and lakes, and 133 species and 10 of the 68 genera are endemic.