''Hylaeamys megacephalus'', also known as Azara's broad-headed oryzomys or the large-headed rice rat, is a species of rodent in the genus ''

Hylaeamys ''Hylaeamys'' is a genus of South American oryzomyine rodents found principally in humid forested areas east of the Andes. The species in this genus have historically been placed in ''Oryzomys''. They are most closely related to ''Euryoryzomys'', ...

'' of family Cricetidae, of which it is the type species. It is found mainly in lowland tropical rainforest from its type locality in Paraguay north through central Brazil, French Guiana,

Guyana Guyana ( or ), officially the Cooperative Republic of Guyana, is a country on the northern mainland of South America. Guyana is an indigenous word which means "Land of Many Waters". The capital city is Georgetown. Guyana is bordered by the ...

Suriname Suriname (; srn, Sranankondre or ), officially the Republic of Suriname ( nl, Republiek Suriname , srn, Ripolik fu Sranan), is a country on the northeastern Atlantic coast of South America. It is bordered by the Atlantic Ocean to the north ...

, and Venezuela onto Trinidad and Tobago. To its west and east, other closely related species of ''Hylaeamys'' are found: '' H. perenensis'' in western

Amazonia The Amazon rainforest, Amazon jungle or ; es, Selva amazónica, , or usually ; french: Forêt amazonienne; nl, Amazoneregenwoud. In English, the names are sometimes capitalized further, as Amazon Rainforest, Amazon Forest, or Amazon Jungle. ...

, '' H. acritus'' in

Bolivia , image_flag = Bandera de Bolivia (Estado).svg , flag_alt = Horizontal tricolor (red, yellow, and green from top to bottom) with the coat of arms of Bolivia in the center , flag_alt2 = 7 × 7 square p ...

, and '' H. laticeps'' and '' H. oniscus'' in the

Atlantic Forest The Atlantic Forest ( pt, Mata Atlântica) is a South American forest that extends along the Atlantic coast of Brazil from Rio Grande do Norte state in the northeast to Rio Grande do Sul state in the south and inland as far as Paraguay and th ...

of eastern Brazil.

Taxonomy

It was first described by Spanish naturalist Félix de Azara. Based on his description, several names were given to the animal, including ''Mus megacephalus'' Fischer, 1814 and ''Mus capito'' Olfers, 1818, both of which were largely forgotten for over a century. When ''capito'' was rediscovered in 1960, it came in use (as ''Oryzomys capito'') for a "species" that included about all species now placed in ''

Euryoryzomys ''Euryoryzomys'' is a genus of rodents in the tribe Oryzomyini of family Cricetidae. It includes six species, which are distributed in South America. Until 2006, its members were included in the genus ''Oryzomys'', but they are not closely related ...

'', ''

'' and ''

Transandinomys ''Transandinomys'' is a genus of rodents in the tribe Oryzomyini of family Cricetidae. It includes two species—'' T. bolivaris'' and '' T. talamancae''—found in forests from Honduras in Central America south and east to southwester ...

''. Later, its scope was restricted, most definitively in a detailed study in 1998 by Guy Musser and coworkers, who also reinstated the older name ''Mus megacephalus'' (as ''Oryzomys megacephalus''). In subsequent years, the western Amazonian ''H. perenensis'' was reinstated as a species and both were moved to the new genus ''Hylaeamys'', because they are not closely related to the type species of ''

Oryzomys ''Oryzomys'' is a genus of semiaquatic rodents in the tribe Oryzomyini living in southern North America and far northern South America. It includes eight species, two of which—the marsh rice rat (''O. palustris'') of the United States and ...

''.

References

Hylaeamys Rodents of South America Mammals of Brazil Mammals of French Guiana Mammals of Paraguay Mammals of Trinidad and Tobago Mammals of the Caribbean Mammals of Guyana Mammals of Suriname Mammals described in 1814 Taxa named by Gotthelf Fischer von Waldheim Taxonomy articles created by Polbot {{Sigmodontinae-stub