ABSTRACT: Accurate taxonomic and distributional information are arguably the most critical components of conservation status assessments but can be greatly affected by misidentifications. The Louisiana pigtoe Pleurobema riddellii is a freshwater mussel proposed as threatened under the US Endangered Species Act. The species belongs to the tribe Pleurobemini, which includes multiple taxa that are inherently challenging to identify without molecular data. We validated historical and recent survey records of P. riddellii using a combination of DNA sequence data and morphological characters to provide a more definitive assessment of range and spatiotemporal trends in distribution. Our comprehensive assessment identified specimens collected from the Pearl drainage as P. riddellii, extending the species’ known range into eastern Gulf of Mexico drainages. Contemporary records were unavailable from the Trinity drainage; however, we designed novel minibarcode PCR primers and used historical DNA from a specimen collected in the late 1800s to confirm the historical presence of P. riddellii at the species’ type locality in the Trinity River near Dallas, Texas, USA. Our range-wide genetic diversity assessment provides strong support for 2 main geographic groups, the Ouachita and all remaining populations, with individuals from the Pearl and Trinity drainages sharing haplotypes with conspecifics from other drainages. Available data suggest P. riddellii has been extirpated from a significant portion of the historical range, including the entire Trinity drainage. Additional surveys in Lake Pontchartrain, Trinity, and other drainages in the eastern periphery of the species’ range may provide additional clarity on the distribution and conservation status of P. riddellii.

中文翻译：

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分子数据验证了 Pleurobema Riddellii（双壳纲：Unionidae）的历史和当代分布，并有助于指导保护和恢复工作

摘要：准确的分类和分布信息可以说是保护状态评估最关键的组成部分，但可能会受到错误识别的极大影响。路易斯安那猪趾Pleurobema Riddellii是一种淡水贻贝，根据美国濒危物种法案被列为受威胁物种。该物种属于 Pleurobemini 部落，该部落包括多个分类群，如果没有分子数据，这些分类群本质上很难识别。我们结合 DNA 序列数据和形态特征验证了P. Riddellii的历史和近期调查记录，以对分布范围和时空趋势提供更明确的评估。我们的综合评估确定从珍珠排水系统采集的样本为P. Riddellii，将该物种的已知分布范围延伸至墨西哥湾东部流域。三一排水系统无法获得当代记录；然而，我们设计了新型迷你条形码 PCR 引物，并使用 1800 年代末收集的样本中的历史 DNA 来确认P. Riddellii在美国德克萨斯州达拉斯附近的三一河的物种模式产地历史上存在。我们的范围范围内的遗传多样性评估为两个主要地理群体（沃希托人和所有剩余种群）提供了强有力的支持，来自珍珠流域和三一流域的个体与来自其他流域的同种人共享单倍型。现有数据表明P. Riddellii已经从历史范围的很大一部分中被消灭，包括整个三一流域。在庞恰特雷恩湖、三一湖和该物种分布范围东部边缘的其他流域进行的额外调查可能会进一步明确P. Riddellii的分布和保护状况。