Biogeographic regionalization identifies natural species assemblages of a given region. In this study, the geographic distribution of chondrichthyan species richness and species assemblages for the Southwest Atlantic were identified. The geographic distribution of 103 chondrichthyans was estimated through modelling. Based on the obtained binary maps, the distribution of chondrichthyan richness was obtained at four taxonomic levels: class Chondrichthyes (chondrichthyans), subclass Holocephali (chimaeras), division Selachii (sharks), and division Batomorphi (batoids). The continental shelf off Uruguay and southern Brazil presented the highest levels of chondrichthyan richness, and a smaller peak was found in El Rincón (northern Argentina). Shark richness concentrated mainly off Lagoa dos Patos (southern Brazil). Batoid richness was maximal off Uruguay and northern Argentina, including modes in El Rincón, San Jorge Gulf, and slope of the Argentinean shelf. Classification analyses revealed the presence of a hierarchical regionalization, with three main and six minor assemblages. Main assemblages are hierarchically identifiable as provinces and minor ones as ecoregions or districts. Two of the main assemblages correspond with the Argentinean and Magellanic Provinces; the third one is identified here for the first time, the Patagonian Slope Province. This regionalization provides the basis for the design of protected area networks for conservation or management purposes.

中文翻译：

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走向西南大西洋软骨鱼类区系的区域化：保护规划的空间框架

生物地理区域划分可确定给定区域的自然物种集合。在这项研究中，确定了西南大西洋软骨鱼类物种丰富度和物种组成的地理分布。通过建模估算了103个软骨鱼类的地理分布。基于获得的二元图，在四个分类学级别上获得了软骨鱼类丰富度的分布：软骨鱼类类（chondrichthyans），Holocephali子类（chimaeras），Selachii子（鲨鱼）和Batomorphi子（类蝙蝠）。乌拉圭和巴西南部附近的大陆架呈现出丰富的软骨鱼类丰富度，而在埃尔·林孔（阿根廷北部）则发现了较小的高峰。鲨鱼的丰富度主要集中在Lagoa dos Patos（巴西南部）附近。在乌拉圭和阿根廷北部，巴蒂德族的丰富度最大，包括埃尔林孔，圣豪尔赫湾和阿根廷大陆架的斜坡。分类分析显示存在分层的区域化，其中有三个主要组合和六个次要组合。主要组合可按层次划分为省份，次要组合可识别为生态区或地区。其中两个主要类别分别对应于阿根廷和麦哲伦各省；第三个是巴塔哥尼亚斜坡省，这是第一次。该区域化为保护或管理目的设计保护区网络提供了基础。有三个主要组合和六个次要组合。主要组合可按层次划分为省份，次要组合可识别为生态区或地区。其中两个主要类别分别对应于阿根廷和麦哲伦各省；第三个是巴塔哥尼亚斜坡省，这是第一次。该区域化为保护或管理目的设计保护区网络提供了基础。有三个主要组合和六个次要组合。主要组合可按层次划分为省份，次要组合可识别为生态区或地区。其中两个主要类别分别对应于阿根廷和麦哲伦各省；第三个是巴塔哥尼亚斜坡省，这是第一次。该区域化为保护或管理目的设计保护区网络提供了基础。