Abstract Biological interactions play an important role in regulating and maintaining natural populations. Like most interactions, parasitism may be influenced by environmental conditions. Therefore, changes caused by human activity may drastically affect the equilibrium of the assemblages of parasitized organisms (hosts). Herein, we described the composition of hemoparasites of anurans from two distinct environments: forest and oil palm plantations. We identified the most frequent groups of blood parasites, and whether infections differ between habitats (forest and plantation) and between microhabitats (arboreal or terrestrial). We collected 128 anurans, of which 46 (36%) were parasitized by hemoparasites. The genus Trypanosoma spp. was found in 30% (n = 37/128) of the infected anurans in both habitats, recorded mostly in terrestrial anurans in oil palm plantations. Apicomplexa hemoprotozoans were also found in 13% (n=17/128) of the anurans, which mainly were terrestrial species collected in oil palm plantations. There was no difference in parasitism between the two assemblies and between the studied microhabitats. This is the first study that has analyzed the ecological relationship between anurans as hosts and their blood parasites, in a region under intense anthropic pressure, in the Brazilian Amazon.

RESUMO Avaliamos neste estudo a composição de espécies, e características ecológicas de uma comunidade de serpentes em área de transição Cerrado-Amazônia, no Centro-Oeste do Brasil (Estado do Mato Grosso). Coletamos os dados durante seis expedições para "Tanguro" (área de estudo) através dos métodos de procura visual, armadilhas de interceptação e queda e encontros ocasionais. Registramos 194 espécimes, distribuídas em 34 espécies, 26 gêneros e oito famílias. As espécies mais abundantes foram Crotalus durissus Linnaeus, 1758 (n = 50), Philodryas olfersii (Lichtenstein, 1823) (n = 15), Philodryas nattereri Steindachner, 1870 (n = 13), Xenodon rabdocephalus (Wied, 1824) (n = 12), Lachesis muta (Linnaeus, 1766) (n = 10) e Erythrolamprus almadensis (Wagler, 1824) (n = 10). A composição de espécies encontrada representa uma combinação entre a fauna de Cerrado e Amazônica.

ABSTRACT The present study encompasses the species composition and ecological characteristics of the snake community in a Cerrado-Amazon transition zone in Midwest of Brazil (state of Mato Grosso). The data were collected during six excursions to the "Tanguro" (study area) by visual encounter survey, pitfall traps with drift fences and non-systematic sampling. We collected 194 specimens, distributed in 34 species, 26 genera, and eight families. The most abundant species were Crotalus durissus Linnaeus, 1758 (n = 50), Philodryas olfersii (Lichtenstein, 1823) (n = 15), Philodryas nattereri Steindachner, 1870 (n = 13), Xenodon rabdocephalus (Wied, 1824) (n = 12), Lachesis muta (Linnaeus, 1766) (n = 10) and Erythrolamprus almadensis (Wagler, 1824) (n = 10). The composition of species found here represents a combination of Cerrado and Amazonian savanna fauna.

The aim of the present study was to describe the species composition and reproductive modes of an anuran community from a transition area between the Amazonia and Cerrado biomes. Data were collected in habitats exhibiting different degrees of anthropogenic degradation. The community (35 species) identified during the present study presented a larger number of reproductive modes when compared with those from Cerrado communities, but smaller than those of other sites in the Amazon. While all nine modes were recorded in the gallery forests of local rivers and streams, anthropogenic habitats (rubber tree orchards and soybean fields) were occupied only by species adapted to environments where humidity is low, typical of the Cerrado. Overall, the anuran fauna of the study area was characterized by species that depend on access to water bodies for their reproduction, with only a few specialized species able to reproduce in dry environments.

We studied the diet of Liophis reginae semilineatus (Wagler, 1824) from eastern Amazon, Brazil, based on the analysis of 182 preserved specimens. Thirty-six individuals had prey in their stomachs; 34 (95%) contained exclusively anurans and 2 (5%) contained both anurans and lizards. The most common prey items were small Leptodactylus sp. (33.3%), followed by Physalaemus ephippifer (Steindachner, 1864) (10.3%). Prey ingested head-first (78%; n = 25) were significantly larger than prey ingested tail-first (22%; n = 7). Females of L. reginae semilineatus have longer and wider heads than conspecific males with the same body length, which correspond to sexual divergences in the diet (size of the prey). No correlation was found between snake head length vs. prey size (SVL, width and mass). Liophis reginae semilineatus is an anurophagous snake that probably forages actively on the ground.