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Abstract It is repeatedly stressed the need to characterize the extant biodiversity in tropical ecosystems. However, inventory studies are still progressing slowly in dry ecosystems, leading to the underestimation of their true biodiversity and hindering conservation efforts. In this study, we present primary and secondary data, along with an updated list of amphibians and reptiles from two localities in the São Francisco-Gurguéia region in Piauí. Additionally, we compare the species composition between nine areas within the Caatinga, which were sampled using standardized methods over the past ten years, to examine broader spatial patterns of community composition. To survey reptiles and amphibians, we employed similar methods and sampling efforts in two areas within the Serra das Confusões National Park (SCNP) region. Our surveys recorded a total of 73 species of amphibians and reptiles, of which 24 are new distribution records for the SCNP region. Consequently, our findings increase the known herpetofauna in the region to 94 species. Despite their proximity, the two sites in the SCNP region exhibited only 42% similarity in species composition, and they differed significantly from other areas within the Caatinga. Furthermore, even the closer Caatinga areas presented differences in species composition, highlighting the necessity to evaluate biodiversity across the landscape and contribute to understanding biogeographic patterns.

Resumo É repetidamente enfatizada a necessidade de caracterizar a biodiversidade vivente em ecossistemas tropicais. No entanto, os estudos de inventário ainda estão progredindo lentamente em ecossistemas secos, levando à subestimação de sua verdadeira biodiversidade e dificultando os esforços de conservação. Neste estudo, apresentamos dados primários e secundários, juntamente com uma lista atualizada de anfíbios e répteis de duas localidades na região de São Francisco-Gurguéia, do Piauí. Além disso, comparamos a composição de espécies entre nove áreas dentro da Caatinga, que foram amostradas usando métodos padronizados nos últimos dez anos, para examinar padrões espaciais mais amplos de composição da comunidade. Para estudar répteis e anfíbios, utilizamos métodos e esforços de amostragem semelhantes em duas áreas na região do Parque Nacional da Serra das Confusões (PNSC). Nossos levantamentos registraram um total de 73 espécies de anfíbios e répteis, das quais 24 são novos registros de distribuição para a região do PNSC. Consequentemente, nossos resultados aumentam a herpetofauna conhecida na região para 94 espécies. Apesar da proximidade, os dois locais na região do PNSC exibiram apenas 42% de similaridade na composição de espécies e diferiram significativamente de outras áreas dentro da Caatinga. Mesmo áreas mais próximas da Caatinga apresentaram diferenças na composição de espécies, destacando a necessidade de avaliar a biodiversidade em toda a paisagem e contribuir para a compreensão de padrões biogeográficos.

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The genus Plasmodium (Plasmodiidae) ranks among the most widespread intracellular protozoan parasites affecting a wide range of mammals, birds, and reptiles. Little information is available about lizard malaria parasites in South America, and the pathological features of the resulting parasitoses remain unknown or poorly understood. To partially fill in these gaps, we conducted blood smear analysis, molecular detection, and phylogenetic and pathological investigations in lizards inhabiting an Atlantic Forest fragment in Paraiba, Brazil. From 104 striped forest whiptails (Kentropyx calcarata) screened for the presence of haemosporidian parasites, 67 (64.4%) were positive. Four of five Amazon lava lizards (Strobilurus torquatus) we collected from this same area were also positive. A total of 27 forest whiptails were infected with a new genetic lineage of Plasmodium kentropyxi and other Plasmodium lineages were also detected. Histopathological analysis in infected forest whiptails revealed systemic intraerythrocytic Plasmodium stages, mainly gametocytes, in the liver, lung, and heart. Also, the liver of infected lizards had mild to moderate levels of Kupffer cell and melanomacrophage hypertrophy/hyperplasia with sinusoid leukocytosis. Overall, our findings suggest that an endemic Plasmodium species causes histological alterations that are not related to major pathological processes in striped forest whiptails.

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Ectoparasites such as hematophagous leeches and monogeneans are common in chelonians, occupying different parts of the body. Thus, the present study aimed to identify and describe the fauna of ectoparasites that infest Phrynops geoffroanus and Mesoclemmys tuberculata to evaluate the effect of host conditions and seasonality (dry and rainy season) on the abundance and composition of ectoparasites. We verified the presence of ectoparasites in 73.2% of the examined turtles, with four species of leeches belonging to Glossiphoniidae, Haementeria brasiliensis sensu Cordero, 1937, Helobdella cf. adiastola, Haementeria sp1., and Haementeria sp2., and one monogenean Polystomatidae, Polystomoides brasiliensis. For both chelonians, we observed a significant difference in the abundance of ectoparasites in relation to sex, biome, and season, which was unrelated to length and mass. Leeches were more frequent in the cavities of the hind limbs in P. geoffroanus, and the anterior limbs of M. tuberculata. The general spatial niche overlap of ectoparasites was high, except for that of the monogenean P. brasiliensis, which did not overlap with those of other leech species. The present study is the first report of the presence of H. brasiliensis and P. brasiliensis parasitizing M. tuberculata, and Helobdella cf. adiastola in a phoretic relationship with P. geoffroanus and M. tuberculata. Finally, the differences in infestation levels may reflect ecological factors, differences in behavioral patterns of the hosts, and different anthropic alterations suffered in the Caatinga and Atlantic Forest biomes.

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We identified Miranda's white-lipped frog ( Leptodactylus macrosternum) as a new host for chiggers ( Hannemania sp.). A total of 57 larvae of Hannemania sp. were found on 31 frogs examined from a semiarid region of northeastern Brazil.

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Two main hypotheses have been proposed to explain the diversification of the Caatinga biota. The riverine barrier hypothesis (RBH) claims that the São Francisco River (SFR) is a major biogeographic barrier to gene flow. The Pleistocene climatic fluctuation hypothesis (PCH) states that gene flow, geographic genetic structure and demographic signatures on endemic Caatinga taxa were influenced by Quaternary climate fluctuation cycles. Herein, we analyse genetic diversity and structure, phylogeographic history, and diversification of a widespread Caatinga lizard (Cnemidophorus ocellifer) based on large geographical sampling for multiple loci to test the predictions derived from the RBH and PCH. We inferred two well-delimited lineages (Northeast and Southwest) that have diverged along the Cerrado-Caatinga border during the Mid-Late Miocene (6-14 Ma) despite the presence of gene flow. We reject both major hypotheses proposed to explain diversification in the Caatinga. Surprisingly, our results revealed a striking complex diversification pattern where the Northeast lineage originated as a founder effect from a few individuals located along the edge of the Southwest lineage that eventually expanded throughout the Caatinga. The Southwest lineage is more diverse, older and associated with the Cerrado-Caatinga boundaries. Finally, we suggest that C. ocellifer from the Caatinga is composed of two distinct species. Our data support speciation in the presence of gene flow and highlight the role of environmental gradients in the diversification process.

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Life history parameters such as diet, reproduction, and sexual dimorphism are crucial to understand ecological and evolutionary forces shaping species traits. Nevertheless, such information is scant in the literature for most Neotropical squamates. Gymnophthalmidae contains over 242 species in 46 genera and includes small-size, mostly terrestrial species, although psamophilic, semi-aquatic, and low vegetation dwellers also occur. Dryadosaura is a monospecific genus - Dryadosaura nordestina Rodrigues et al., 2005 - , occurring in Atlantic Forest areas from Rio Grande do Norte to Northern Bahia, and little is known about its ecology and natural history. We analyzed the species' diet, reproduction, and sexual dimorphism based on 170 specimens deposited in museum collections. Dryadosaura nordestina is considered generalist and active forager, based on dietary items. Arthropods, especially ants and insect larvae, dominate the diet. The reproductive period shows a peak during the rainy season (May through June), while recruitment occurs from July through November. Males are significantly larger than females, and sexes can also be distinguished based on shape variables: males have higher heads and longer bodies, while body height and width are larger in females.(AU)

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Life history parameters such as diet, reproduction, and sexual dimorphism are crucial to understand ecological and evolutionary forces shaping species traits. Nevertheless, such information is scant in the literature for most Neotropical squamates. Gymnophthalmidae contains over 242 species in 46 genera and includes small-size, mostly terrestrial species, although psamophilic, semi-aquatic, and low vegetation dwellers also occur. Dryadosaura is a monospecific genus - Dryadosaura nordestina Rodrigues et al., 2005 - , occurring in Atlantic Forest areas from Rio Grande do Norte to Northern Bahia, and little is known about its ecology and natural history. We analyzed the species' diet, reproduction, and sexual dimorphism based on 170 specimens deposited in museum collections. Dryadosaura nordestina is considered generalist and active forager, based on dietary items. Arthropods, especially ants and insect larvae, dominate the diet. The reproductive period shows a peak during the rainy season (May through June), while recruitment occurs from July through November. Males are significantly larger than females, and sexes can also be distinguished based on shape variables: males have higher heads and longer bodies, while body height and width are larger in females.

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Parasites are natural regulators of their host populations. Despite this, little is known about variations in parasite composition (spatially or temporally) in environments subjected to water-related periodic stress such as the arid and semiarid regions. The objective of this study was to evaluate the spatial-temporal variation in endoparasite species' abundance and richness in populations of Neotropical Cnemidophorus ocellifer, Tropidurus hispidus, and Tropidurus semitaeniatus lizards in the semiarid northeast of Brazil. The location influenced the abundance of parasites in all analyzed lizard species, while season (dry and rainy) only influenced the total abundance for T. hispidus. In all seasons, males significantly showed more endoparasites than females in all lizard species, although for T. hispidus, this difference was only found in the dry season. Seasonal variations affect the abundance patterns of parasites. Likely, variables include environmental variations such as humidity and temperature, which influence the development of endoparasite eggs when outside of the host. Further, the activity of the intermediate hosts and the parasites of heteroxenous life cycles could be affected by an environmental condition. The variation in the abundance of parasites between the sampling areas could be a reflection of variations in climate and physiochemical conditions. Also, it could be due to differences in the quality of the environment in which each host population lives.

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The niche expansion and niche variation hypotheses predict that release from interspecific competition will promote niche expansion in depauperate assemblages. Niche expansion can occur by different mechanisms, including an increase in within-individual, among-individual, or bimodal variation (sexual dimorphism). Here we explore whether populations with larger niche breadth have a higher degree of diet variation. We also test whether populations from depauperate lizard assemblages differ in dietary resource use with respect to variation within and/or among individuals and sexual dimorphism. We found support for the niche expansion and niche variation hypotheses. Populations in assemblages with low phylogenetic diversity had a higher degree of individual variation, suggesting a tendency for niche expansion. We also found evidence suggesting that the mechanism causing niche expansion is an increase in variation among individuals rather than an increase in within-individual variation or an increase in bimodal variation due to sexual dimorphism.

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