2026-08-062026-08-062026-07-16GORDO, Vinícius Cunha. DNA Barcoding revela diversidade molecular na espécie Eleotris melanosoma Bleeker, 1853 (Eleotridae: gobiiformes). Orientador: Marcelo Nazareno Vallinoto de Souza; Coorientadora: Aurycéia Jaquelyne Guimarães da Costa. 2026. 18 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: . Acesso em: .https://bdm.ufpa.br/handle/prefix/9859The family Eleotridae comprises amphidromous fishes commonly known as "sleepers", whose taxonomic identification is historically complex due to extreme morphological conservatism and the occurrence of cryptic species. The objective of this study was to diagnose the taxonomic status of different populations of Eleotris melanosoma through DNA Barcoding and automated species delimitation. Sequences of the mitochondrial Cytochrome C Oxidase Subunit I (COI) gene, totaling an alignment of 573 base pairs (bp) and encompassing 14 species of the genus Eleotris, were retrieved from public databases and analyzed using the Neighbor-Joining (K2P) clustering method and the Automatic Barcode Gap Discovery (ABGD) algorithm. The distribution analysis of genetic distances revealed a striking bimodal pattern, showing a welldefined barcode gap that established a stable consensus of exactly 20 Molecular Operational Taxonomic Units (MOTUs) for the genus. The phylogenetic topology demonstrated that E. melanosoma does not compose a single homogeneous clade, dividing instead into three genetically divergent and geographically structured lineages: Lineage 1, corresponding to specimens from Indonesia and Palau (intra-specific divergence of 0.43%); Lineage 2, which encompasses individuals from French Polynesia and Solomon Islands, presenting the highest internal divergence (1.3%); and Lineage 3, linked to the Eleotris diamsoi complex in the region of Madagascar, Mayotte, and South Africa (0.15%). The inter-specific pairwise genetic divergence (p-distance) within the complex reached 5.4% between Lineages 1 and 2, and up to 7.3% in relation to Lineage 3, confirming the existence of cryptic species under the classical morphotype of E. melanosoma. Additionally, the analyses recovered structured clusters for Eleotris fusca and kept the sequences of Eleotris perniger aggregated into a single MOTU, albeit under a relatively high intra-specific divergence of 1.3%, suggesting an incipient geographic differentiation process or residual gene flow. The results confirm the robustness of the COI gene combined with the ABGD algorithm as fundamental molecular tools to refine evolutionary hypotheses and guide an integrative taxonomic approach within the family Eleotridae.Acesso AbertoEspécies crípticasTaxonomia IntegrativaCOIABGDDiversidadeDelimitação de espéciesCryptic speciesIntegrative taxonomyDiversitySpecies delimitationCNPQ::CIENCIAS BIOLOGICASTrabalho de Curso - Graduação - MonografiaAttribution-NonCommercial-NoDerivs 3.0 Brazil