DNA barcoding identifies three species of croakers (Pisces, Sciaenidae) in the ichthyoplankton of the High Paraná River

Abstract In the province of Misiones (Argentina), the filling of the Yacyretá Reservoir (Argentina-Paraguay) to its final dimensions in 2011 formed new aquatic ecosystem, e.g., Garupá Stream was converted into a subreservoir. Reports have been made in this stream of adult individuals and spawning of the Family Sciaenidae, excellent colonizers of modified environments. The larvae of this family are morphologically similar, particularly among Pachyurus and Plagioscion species, making taxonomic differentiation difficult. In the present work, sciaenidae larvae were characterized molecularly at the cytochrome c oxidase subunit I gene in order to determine which species use this environment for reproduction. Additionally, genetic distances, Barcode Index Number (BIN) and Automatic Barcode Gap Discovery method (ABGD) were estimated and phylogenetic trees were reconstructed. The results indicated the presence of Plagioscion ternetzi and Pachyurus bonariensis larvae, and for the first time in tributaries of the region, Plagioscion squamosissimus. The incorporation of P. bonariensis and P. squamosissimus to the faunistic assemblage of ichthyoplankton in the Garupá Stream supports better characterization of the species richness of this secondary watercourse modified by the Yacyretá Reservoir, and advancement in our understanding of use of this area for reproduction.

摘要：阿根廷米西奥内斯省境内，由阿根廷与巴拉圭共建的亚西雷塔水库于2011年蓄水至设计最终规模，由此形成了全新的水生生态系统——例如加鲁帕溪被改造为子水库。该水域已有记录显示石首鱼科（Sciaenidae）成体存在且存在产卵行为，该类群是受干扰生境的优秀拓殖者。该科鱼类的幼虫形态极为相似，尤其是短须石首鱼属（Pachyurus）与斜纹鲈属（Plagioscion）的物种之间，这使得分类鉴定难度极大。本研究以细胞色素c氧化酶亚基I（cytochrome c oxidase subunit I, COI）基因为分子标记，对采集自该水域的石首鱼科幼虫进行分子特征分析，以明确哪些物种利用该生境完成繁殖活动。此外，本研究还估算了遗传距离，分析了条形码索引号（Barcode Index Number, BIN）与自动条形码间隙发现法（Automatic Barcode Gap Discovery, ABGD），并构建了系统发育树。研究结果显示，该水域存在特氏斜纹鲈（Plagioscion ternetzi）与博纳里短须石首鱼（Pachyurus bonariensis）的幼虫，同时本研究首次在该区域支流中发现了鳞皮斜纹鲈（Plagioscion squamosissimus）的幼虫。将博纳里短须石首鱼（P. bonariensis）与鳞皮斜纹鲈（P. squamosissimus）纳入加鲁帕溪鱼卵仔鱼群落的区系组成，有助于更精准地刻画亚西雷塔水库改造后的该次级水道的物种丰富度特征，同时加深我们对该区域繁殖生境利用情况的认知。