2026-03-312026-03-312026-02-26CUNHA, Jamille do Rosário. O dimorfismo sexual secundário de Crenuchus spilurus Günther, 1863 (Characiformes; crenuchidae) - entre igarapés de florestas alagáveis e de campos naturais. Orientadora: Janice Muriel Fernandes Lima da Cunha, Coorientador: Luiz Antônio Wanderley Peixoto. 2026. 32 f. Trabalho de Curso (Licenciatura em Ciências Biológicas) – Faculdade de Ciências Biológicas. Instituto de Estudos Costeiros, Campus Universitário de Bragança, Universidade Federal do Pará, Bragança-PA, 2026. Disponível em: https://bdm.ufpa.br/handle/prefix/9420. Acesso em: .https://bdm.ufpa.br/handle/prefix/9420Secondary sexual dimorphism (sSD) is widespread in Characiformes, and can be characterized by variations in size, color patterns, fins with spines, or the presence of glandular organs in conditions attractive to potentially reproductive partners. However, despite these characteristics, no sexual differences have yet been investigated in Crenuchus spilurus for anatomical complexes such as osteology. Thus, we investigated sexual dimorphism in the Amazonian fish Crenuchus spilurus through morphometric, meristic, and osteological analyses, and inferred variations in color pattern based on variations in water color from flooded forests and natural fields. In the anatomical analyses, we found significant variation in the size of the unpaired fins when comparing them between sexes. The elongation of the dorsal fin and the lanceolate shape of the anal fin in males are distinct from the fins of females, which are characterized by a proportionally short dorsal fin and an approximately rounded anal fin. Variations in color pattern are classic characteristics of secondary sexual dimorphism for this Amazonian fish. Standard length and maxilla length are the main secondary sexual dimorphism attributes in C. spilurus, with morphometry evaluated via principal component analysis. The longer maxilla in males and variations in the premaxilla and dentary indicate osteological variations to be discussed in the morphofunctional and ecological context between males and females of the analyzed species. In addition, the physical and chemical variations present in the sampled streams corroborate the literature on the variation in color pattern recorded between populations of the Caeté and Maninteua basins in coastal Amazonia. Furthermore, the importance of conserving neotropical river environments and Amazonian biodiversity is reinforced.Acesso AbertoAmazôniaMorfologiaMorfometriaPeixeAmazonMorphologyMorphometryFishCNPQ::CIENCIAS BIOLOGICAS::ZOOLOGIA::MORFOLOGIA DOS GRUPOS RECENTESTrabalho de Curso - Graduação - MonografiaAttribution-NonCommercial-NoDerivs 3.0 Brazil