A riqueza e diversidade de anfíbios anuros da Serra do Mendanha, Estado do Rio de Janeiro, RJ: grau de conservação da floresta, variação altitudinal e uso de recursos hídricos

Abstract

The frogs that inhabit the Atlantic Forest, especially in the dense rain forest, are little known in various aspects of its ecology, there is little information available in scientific literature. These data are limited to a few locations, usually studies in the remaining fragments of southeastern Brazil. The well preserved forest covering 3,300 ha of Serra do Mendanha, although located in the metropolitan region of Rio de Janeiro, had not known its frogs. In this study, we collected ecological information about the species that inhabit the region, especially the assembly found in the leaf litter covering the soil with the use of different methodologies: pitfall traps; plots; visual and auditory transects and occasional encounters and abiotic data of the regional environment (depth of litter, pH levels, rate of dissolved oxygen, temperatures of air and water, air humidity). Vouchers specimens were fixed and deposited in the collection of amphibians of the Museu Nacional, Rio de Janeiro. The frogs of the Serra do Mendanha is composed of at least 44 species which are distributed in 12 families, being the Hylidae family with the largest number of species (50%, n = 22), while Physalaemus signifer was the most abundant species (18%, n = 272), being an inhabitant of leaf litter. The species Rhinella ornata contributed with the highest biomass (m = 548 g). We identified a new species of frog (Brachycephalidae), which also inhabits the leaf litter of altitude quotas above 700 m (a.s.l.). Biogeographically community of frogs in the study area indicated to be more similar (68%) to the community in the region of Serra da Tiririca. Comparing the three types of physiognomies or mesohabitats existing in the Serra do Mendanha, in terms of richness and diversity, secondary forest indicated that it had the highest levels, followed by undisturbed forest and banana plantations. The assemblage of frogs that inhabit the leaf litter of the Serra do Mendanha comprises nine species, which differed slightly along an altitudinal gradient (0 900 m a.s.l.), with the record of the Euparkerella brasiliensis, H. binotatus, Leptodactylus marmoratus and Zachaenus parvulus and in almost all altitudes. The altitude, slope and depth of leaf litter were the abiotic variables that most influenced the distribution of abundance species richness of leaf litter. In the wet season (September to March) the density of litter frogs was 10.4 ind./100m2, while in the dry season (April to August) there was a reduction of 34.6% (6.8 ind./100m2). The assemblages of anurans utilized the available water resources in the Serra do Mendanha (rainwater, streams, phytotelma, rivers and air humidity), in different ways, directly related to the reproductive mode of each species. The altitude, water temperature and pH affected the distribution of tadpole species in different breeding sites. The reproductive mode 1 was the most common (n = 18) among the 14 modes identified. The study of 12 pools (lentics and lotics) indicated that they differed consistently among themselves; either in its size, the composition of their assemblages of tadpoles and their abiotic components. Several predators of tadpoles were found in some pools. The assembly of tadpoles from each pool indicated that it is shaped by the interaction of different environment, ecological and phylogenetic factors for each species