https://repositorio.ufms.br/handle/123456789/1985 2026-03-27T22:19:42Z https://repositorio.ufms.br/handle/123456789/14090 Título: Composição e distribuição temporal do ictioplâncton no rio Piquiri, bacia do alto rio Paraguai Abstract: The aim of this study was to evaluate the composition and temporal distribution of ichthyoplankton in the Piquiri River and its relationship with environmental variables to support fish fauna conservation actions. Ichthyoplankton samples were collected in two cycles: between November 2017 and March 2018 (first cycle) and between October 2018 and March 2019 (second cycle). Parameters such as temperature, pH, electrical conductivity, and rainfall were analyzed. The taxonomic composition analysis revealed 25 species, six of which were long-distance migrators. Piaractus mesopotamicus and Pseudoplatystoma spp. predominated, suggesting that the area is used as a spawning site for migratory species. The highest densities of eggs and larvae occurred in December (first cycle) and February (second cycle), associated with increased conductivity and pH and decreased temperature. These results contribute to understanding reproductive patterns and their dependence on physicochemical factors, as well as reinforce the need for conservation actions for fishery resources in the region, emphasizing the importance of habitat connectivity for maintaining aquatic biodiversity. Keywords: Eggs and larvae of fishes, Migratory species, Pantanal, reproduction, spawning áreas. Tipo: Dissertação 2025-01-01T00:00:00Z https://repositorio.ufms.br/handle/123456789/11855 Título: Taxonomia de Epictia vellardi (Laurent, 1984) (Leptotyphlopidae, Serpentes) com base em dados de morfologia externa e interna Abstract: 'Scolecophidia' are snakes characterized by their small size, commonly known as blind snakes, worm snakes, or thread snakes, exhibiting various adaptations associated with fossorial and semifossorial lifestyles. Given the importance of internal and external morphology studies of Leptotyphlopidae representatives, especially in their delimitation and generic allocation, a refined quantitative and qualitative study is necessary to contribute not only taxonomic information but also insights into potential ontogenetic or sexual variation within this family. This study aimed to conduct a taxonomic review and redescribe Epictia vellardi, presenting detailed data for the first time on its external and internal morphology, including skull description, atlas and axis, pelvic girdle, cranial and post-cranial cartilaginous elements, as well as intra-specific variations. Laurent's original description (1984) had weaknesses warranting a redescriptive effort, primarily due to limited sampling of the holotype and a paratype, succinct morphological data, and outdated methodology. Additionally, considering the species' placement in Epictia based on a phylogenetic hypothesis from exclusively molecular data, external and internal morphology data were crucial to complement molecular analyses, enhancing our understanding of its systematics. The study presented the largest sample size ever recorded for scolecophidians, including males and females, revealing no sexual dimorphism. Scolecophidia are generally undersampled, leading to the belief that they are rare. However, the study found a high population density of snakes in the urban region of Corumbá (MS), suggesting that their perceived rarity is more due to sampling biases than actual scarcity. The research provides new records for Anastácio, Aquidauana, and Ladário (MS). The absence of records in Brazil, Paraguay, and Argentina may reflect sampling gaps, common also among other snake species inhabiting the region. We confirm the correct placement of E. vellardi in the genus due to the non-participation of the basioccipital in the formation of the foramen magnum and the presence of paired nasals and supraoccipitals. E. vellardi showed the absence of intercentrum I in the atlas, a characteristic also observed in other species of the genus, although the dorsal region of the vertebra is not fused. This pattern had not been described in Epictia before and may be associated with the phenomenon of miniaturization. The information from this study could contribute to the recognition of Leptotyphlopidae taxa. Tipo: Dissertação 2025-01-01T00:00:00Z https://repositorio.ufms.br/handle/123456789/11845 Título: Variação morfológica e análise molecular de Dipsas turgida (Cope, 1868) (Serpentes, Dipsadidae) Abstract: Dipsas turgida is a non-venomous, medium-sized snake with strictly nocturnal and terrestrial habits, feeding primarily on mollusks. Phylogenetic studies have identified this species as the sister species of D. mikanii, while another study suggested its non-monophyletic status. These findings indicate that clades with ambiguous or weak support are concentrated within the subfamily Dipsadinae, emphasizing the need for further studies. The species was revised by Peters in 1960, who described its morphological variation based on 14 specimens, only three of which were from Central-West region of Brazil. In this study, we analyzed the external morphology of 199 specimens of D. turgida, 133 of which are from Central-West region of Brazil and tested its phylogenetic placement using molecular data. Dipsas turgida was recovered as the sister species to D. mikanii, and formed two clades with considerable genetic distance and high support values. The molecular data, combined with the observed morphological variations, indicate that D. turgida may include an undescribed species. Tipo: Dissertação 2025-01-01T00:00:00Z https://repositorio.ufms.br/handle/123456789/11658 Título: Variação morfológica de Xenodon merremii (Wagler, 1824): impacto de fatores geográficos, ontogenéticos e sexuais Abstract: Morphological variations within and among species are crucial for understanding evolutionary processes, as they influence ecological and adaptive functions. In snakes, environmental factors related to species distribution, as well as ontogenetic and sexual characteristics, shape diverse morphological traits. This morphological diversity is particularly evident in widely distributed species. Xenodon merremii emerges as an ideal model to investigate interactions between postnatal development and environment in morphology, given its: (1) extensive geographic distribution, (2) reproductive maturity attained at varying sizes across sexes and regions, and (3) polymorphism in coloration. Based on these premises, we aimed to characterize the species' morphological variations in response to its geographic distribution (i.e., ecoregions) and describe how ontogenetic variations influence the manifestation of sexual dimorphism. We sampled 909 specimens from various locations, collecting six morphological variables including linear measurements, scale counts, color pattern, and analysis of head shape and cephalic shields. We observed distinct morphological patterns among ecoregions, with variations in body size and scale number, highlighting the influence of regional factors on species morphology. Regarding coloration, we noted variable distribution of patterns, as individuals are born with a single pattern that diversifies as they grow. Geometric morphometrics also revealed differences in centroid sizes and allometric trajectories, with significant variations between sexes and ontogenetic stages. These results indicate rapid morphological changes in early life stages, diminishing as individuals reach maturity, contributing to sexual dimorphism, especially in larger individuals. Thus, this study contributes to understanding microevolutionary patterns, emphasizing differences among ecoregions and how ontogenetic variations influence the expression of sexual dimorphism. Tipo: Dissertação 2025-01-01T00:00:00Z