Amphibia , Anura , Hylidae , Hypsiboas raniceps Cope , 1862 : Distribution extension

Hypsiboas raniceps is a large treefrog typically found in the Cerrado and Caatinga biomes. Here we provide information about new records of this species in the Atlantic Forest and raise some hypotheses that could explain the late record of this species in this biome.

Hypsiboas raniceps Cope, 1862 (Figure 1) is a large Neotropical hylid frog commonly found in the Cerrado and Caatinga biomes (Arzabe 1999; Guimarães and Bastos 2003), being the most widespread species of the Hypsiboas albopunctatus group.Besides occurring in central and northeastern Brazil, H raniceps also inhabits the Brazilian Amazon Basin, south Colombia, north French Guiana, Amazonian Bolivia, Paraguay, and northeastern Argentina (Frost 2009).
Although H. raniceps is known to occur in tropical forests, such as the Amazonia (Heyer 1977), there are no records in the Atlantic forest of southeastern Brazil, or any coastal region in the south or southeast part of the country.
The Atlantic forest is Brazil's most fragmented biome, due to deforestation (Morellato and Haddad 2000).However, some good quality patches are preserved as conservation unities, such as the Parque Estadual Campina do Encantado (São Paulo 1998).According to Haddad and Sazima (1992), some anuran species benefit from forest fragmentation by spreading their geographic ranges.Additionally, habitat fragmentation increases the vulnerability of the fragments to invasion by allochthonous and native species that occupy adjacent open areas (Paton 1994;Haddad and Prado 2005).
Although this new record for H. raniceps does not greatly extend its geographic distribution, the major contribution of our data is the record of the species in Atlantic forest areas in the state of São Paulo.There are three possible explanations for the new record of H. raniceps in the Atlantic forest: 1) the region may represent one of the extremes of the species' distribution range, where it was never registered before; or 2) during the Pleistocene glaciation the species may have occupied areas that currently   Haffer 1969;Vanzolini and Williams 1981), which could also explain its occurrence in the Atlantic rainforest of northeastern Brazil; or 3) the species is expanding its distribution range due to deforestation of the Atlantic forest.
The third alternative seems to be more plausible, since H. raniceps was collected in pastures, and also justifies its occurrence in coastal areas of northeastern Brazil, where the deforestation of the Atlantic forest is known since the XVI Century.However, we cannot reject the first hypothesis, as the number of surveys and publications is still insufficient, considering the high diversity of anurans in the Atlantic forest.Phylogeographical studies could provide valuable information about the current and past demographic history of H. raniceps.Additionally, statistical modeling methods may be used as a complementary tool to understand how the environment correlates with species distribution patterns (Giovanelli et al. 2010).These approaches are fundamental not only to determine the geographical extension of particular species and event(s) responsible for it but also to elucidate the history of biomes.

Figure 1 .
Figure 1.A male Hypsiboas raniceps calling in the margin of an artificial lake in Pariquera-Açu, state of São Paulo, southeastern Brazil.

Figure 2 .
Figure 2. Map showing the new localities where Hypsiboas raniceps was recorded.Circles indicate new records obtained from herpetological collections and from the literature on anuran communities for northeastern Brazil.The triangle represents our new record from Pariquera-Açu, state of São Paulo, southeastern Brazil.