Large sampling effort is not related to richness and geographic distribution of Cladocera (Crustacea, Branchiopoda) in the Brazilian Savannah

The Cerrado is home of the headwaters of some important Brazilian basins. Such biome has a high diversity of animal and plant species with a high degree of endemism. This premise is well documented for microcrustaceans of the Superorder Cladocera, although many areas still need sampling. In this context, the objective of the present investigation was to evaluate the geographic distribution and richness of Cladocera in the Cerrado biome. The analyzed data were obtained from the authors database on Brazilian Cladocera and distributed according to the hydrographic regions comprised in the biome. Species distribution models were used to determine the areas with the highest probability of occurrence of Cladocera. We analyzed 125 publications, resulting in 2829 records. In total, we obtained 161 taxa, belonging to 48 genera and seven families. Regarding the Hydrographic Regions, Paraná presented the highest richness, followed by TocantinsAraguaia and São Francisco. Our result indicates that most studies are concentrated in certain areas. Furthermore, the species distribution models indicated that transition areas between biomes have the highest probability of occurrence of genera and families. Our results indicate significant gaps in the knowledge, making it necessary to expand inventories and ecological studies in areas still unsampled.

塞拉多（Cerrado）是巴西若干重要流域的源头所在地。该生物群系拥有极高的动植物物种多样性，且特有程度显著。这一结论在隶属于枝角超目（Superorder Cladocera）的微甲壳动物类群中已有充分文献佐证，尽管仍有诸多区域有待开展采样调查。在此研究背景下，本探究的目标为评估塞拉多生物群系内枝角类（Cladocera）的地理分布与物种丰富度。本次分析所用数据源自作者团队构建的巴西枝角类数据库，并依据该生物群系涵盖的水文区域（Hydrographic Regions）进行分布梳理。研究采用物种分布模型（Species Distribution Models）以确定枝角类出现概率最高的区域。本研究共分析125篇文献，最终得到2829条记录，总计涵盖161个分类单元，隶属于48个属与7个科。就水文区域而言，巴拉那（Paraná）流域的物种丰富度位居首位，其次为托坎廷斯-阿拉瓜亚（Tocantins-Araguaia）与圣弗朗西斯科（São Francisco）流域。研究结果显示，绝大多数现有研究集中于特定区域。此外，物种分布模型表明，不同生物群系间的过渡区域拥有最高的属与科出现概率。本研究结果揭示了当前认知存在的显著空白，亟需在尚未采样的区域拓展物种编目与生态学研究工作。