14 The Frogs of the Ilha de Maraca MARCIO MARTINS Universidade de Amazonas, j\tfanaus, Bra:;il SUMMARY

Faunal surveys in northern Roraima, Brazil, revealed the presence of 38 species of frogs, 28 of them known to occur on the riverine island of Maraca. The region surveyed is part of the zoogeographical region called Guianan, and its anuran fauna has a complex history and includes many endemic species as well as widespread South American or Amazonian species. Four bufonids, one dendrobatid, ten hylids, ten leptodactylids, one microhylid and two pseudids were recorded for Maraca. Ten additional species were recorded for other localities less than 130 km from Maraca, and most of them may also occur on the island. The anuran fauna of northem Roraima is poor when compared with other Amazonian regions, probably because of its long dry season. Most species found in northern Roraima are widespread in the llanos and savanna habitats of the region and of southern and central Venezuela. Considering 30 relatively well-identified species from northem Roraima, 48 % of them are widespread in South America, 27 % widespread in Amazonia and 23 % are endemic to the Guianan region. Patterns of habitat uti lization in Maraca are similar to those found in other ncotropica