In this study, we made an inventory of the stream and headwater ichthyofauna of the left bank of the Itaipu Dam Reservoir, located in the lower part of the Upper Paraná River basin, using an integrative approach of molecular and morphological data. The area is located in the western portion of the Paraná state in Brazil, in an area of about 8,000 km² highly impacted by deforestation and intensive agriculture. For taxonomic identification of species, we used an identification key combined with the DNA barcoding approach. We found 48 species belonging to six orders, 13 families, and 37 genera. The Siluriformes and Characiformes were the most representative orders (75%) and the Characidae was the most representative family (20.8%). Nine species prevailed in this region, making up to 86% of all specimens collected. The integrative approach proved to be useful by allowing the unambiguous identification of all species, including those cases in which morphological characters were not conclusive for species identification, cases of cryptic species, and species with high morphological plasticity. In addition, the integrative approach highlighted six to 13 new putative species depending on the approach considered. Our study provides a relevant contribution to the knowledge of fish diversity in a poorly studied area of the Paraná River basin. We showed that the use of an integrative approach in inventory studies improves species identification and the discovery of new, cryptic, and overlooked species, being a powerful and necessary tool to quantify biodiversity.

在这项研究中，我们使用分子和形态学数据的综合方法，对位于上巴拉那河流域下部的伊泰普水库水库左岸的河水和上游水库鱼类养殖场进行了盘点。该地区位于巴西巴拉那州的西部，面积约8,000 km ²受到毁林和集约化农业的严重影响。对于物种的分类识别，我们使用了结合了DNA条形码方法的识别密钥。我们发现48个物种属于6个目，13科和37属。鸭形目和Characiformes是最有代表性的订单（75％），而Characidae是最有代表性的科（20.8％）。该地区共有9种，占所有标本的86％。通过允许对所有物种进行明确鉴定，包括那些形态特征不能确定物种鉴定的案例，隐性物种和具有高形态可塑性的物种，这种综合方法被证明是有用的。此外，根据所采用的方法，综合方法强调了6至13个新的推定物种。我们的研究为巴拉那河流域研究欠佳的地区的鱼类多样性知识提供了重要贡献。我们表明，在清单研究中使用综合方法可以改善物种识别以及发现新的，隐秘的和被忽视的物种的能力，这是量化生物多样性的强大而必要的工具。