Thaís Barreto Guedes

O livro destaca a lacuna de materiais didáticos e científicos acessíveis sobre identificação de serpentes, prevenção, primeiros socorros e tratamento de acidentes ofídicos no estado do Maranhão.

Understanding the spatial distribution of species in megadiverse regions such as the Neotropics has fascinated naturalists since the 19th century (Wallace 1852). There is a consensus that current s...

Snakes are a valuable yet understudied taxon for investigating evolutionary adaptations in the vertebrate retina. They possess up to three visual pigments: a short‐wavelength‐sensitive opsin (SWS1), a medium/long‐wavelength‐sensitive opsin (LWS), and rhodopsin (RH1). Nocturnal snakes have duplex retinas containing both rod and cone photoreceptors, whereas diurnal caenophidian (“advanced”) snakes exhibit simplex “all‐cone” retinas, lacking morphologically typical rods. In this study, we analyzed photoreceptor morphology in the retinas of caenophidian snakes using high‐resolution scanning electron microscopy (SEM) and examined visual‐opsin expression patterns with immunohistochemistry (IHC). Our analyses revealed remarkable interspecific variability in visual‐cell morphology. Light microscopy showed that in all sampled diurnal caenophidians, photoreceptors expressing RH1 exhibit a gross cone‐like morphology. However, SEM analysis revealed a subset of photoreceptors with distinct features—thinner inner segments and rod‐like synaptic terminals—suggesting they are transmuted, cone‐like rods. In retinal sections from nocturnal caenophidian snakes, coexpression of the cone opsins SWS1 and LWS in individual cones was observed, whereas rhodopsin expression remained restricted to morphologically typical rods and showed no coexpression. In contrast, diurnal caenophidians commonly coexpress rhodopsin and SWS1 in single cones, with some instances of triple coexpression (SWS1, RH1, and LWS) in single cones. We evaluated the patterns of spatial distribution of RH1‐ and SWS1‐expressing photoreceptors, as well as SWS1 + RH1 multiopsin cones, in wholemounted retinas of ten species. Our findings revealed considerable species‐specific variation in photoreceptor density, topography, and opsin coexpression patterns. IHC results suggest that in some species, rhodopsin is not only expressed in transmuted, cone‐like rods but may also be co‐opted by UV/violet‐sensitive (SWS1‐expressing) cones. These findings underscore the exceptional diversity and adaptive innovation in snake visual systems. The unique features and striking interspecific differences in their photoreceptors highlight snakes as an outstanding taxon for studying vertebrate visual‐system function and evolution.

Mountains are hotspots of biodiversity and endemism, but biogeography and diversification in tropical montane grasslands remain poorly understood. We reviewed hypotheses explaining the origin of vertebrate fauna ranging from phylogeography to community-scale patterns, while also considering historical biogeography and macroevolutionary dynamics in campo rupestre in the Espinhaço Range. We conducted a systematic review of papers published in 1945–2023 on vertebrate ecology, biogeography, and diversification in campo rupestre. The vertebrate fauna of campo rupestre is characterized by high levels of biodiversity and endemism relative to area extent across most taxa. Unfortunately, such diversity is increasingly threatened, with ~20% of endemic species listed on the IUCN Red List. Hummingbirds are key pollinators, whereas seed dispersal is performed primarily by generalist birds, small mammals, and lizards. A combination of isolation, range shifts, and species persistence played key roles in shaping diversification dynamics in these ancient mountains. High levels of diversity, endemism, and the occurrence of threatened species underscore the pressing need for funding conservation of the outstanding biodiversity in the Espinhaço Range. We propose a research agenda to fill knowledge gaps and promote research needed to provide a more complete understanding of the biogeographical scenario and accelerate protection strategies.

Pentastomida are lung parasites of a variety of hosts, mainly reptiles. Raillietiella is the genus with the largest number of species, whose taxonomic identification is still largely based on morphological data alone. In this classification, differences divide the genus into morphotypic groups. The Raillietiella parasites of insectivorous lizards, for example, are divided into “Group I” with species with hooks with sharp tips and “Group II” with posterior hooks with blunt tips. In the present work, we used molecular analysis to infer the morphological variation in hooks and size of specimens of Raillietiella mottae, parasites of several species of insectivorous lizards. Our results demonstrate that morphological differences comprise a phenotypic plasticity of a single species, whose variation is associated with host species, with females being larger and with hooks with blunt tips in nocturnal geckos and smaller ones with sharp tips in diurnal insectivorous lizards of different species, sizes, and habitats.

Brazil stands out for presenting the highest amphibian anuran diversity in the world. However, taxonomic studies that address characteristic of larval stage of anurans are incipient, representing only 62% of known species. We assess the species diversity of tadpoles from eastern Maranhão state, mid-northern region of Brazil based on morphological and molecular identification (i.e., 16S rRNA gene fragment), and we also provide characteristics of the habitats occupied by each species. We carried out 30 field samplings during 13 months in 16 environments along an ecotonal area, over five cities inside the limits of state of Maranhão, between the Maranhão Babaçu Forest and Cerrado ecoregions. We searched for tadpoles in a variety of water bodies, and the tadpoles that reached the developmental stage between 34 to 40 Gosner were morphologically identified. The tadpoles collected herein represent 26 species belonging to five families. The external morphology enabled the identification of 24 species, while the molecular data recognized 22 unique evolutionary units. The most represented family was Hylidae (Hylinae 11 spp., Phyllomedusinae one spp.) followed by Leptodactylidae (Leptodactylinae seven spp., Leiuperinae three spp.), Microhylidae (Gastrophryninae two spp.), and Bufonidae (two spp.). Our results show that oral morphology was the most important character for identifying tadpoles based on morphology, and the specific 16S rRNA primer was suitable for molecular identification. This study pioneers the use of both morphological and molecular data to identify tadpoles in the state of Maranhão. It also provides, for the first-time, habitat characteristic for the species. Our study reveals a high number of anuran species sampled at the larval stage in the region, identifies species that require further taxonomic and systematic attention, and extends the geographic distribution of six species, three of which represent new occurrences for the state. Our results strengthen the hypothesis that the diversity of amphibians from Maranhão is underestimated and highlight the importance of herpetological inventories in poorly sampled areas, decentralizing the knowledge of biodiversity.