Major geological processes have shaped biogeographical patterns of riverine biota. The Edwards Plateau of central Texas, USA, exhibits unique aquatic communities and endemism, including several species of freshwater mussels. Lampsilis bracteata (Gould, 1855) is endemic to the Edwards Plateau region; however, its phylogenetic relationship with other species in the Gulf coastal rivers and Mississippi River basin is unknown. We evaluated phylogenetic relationships, shell morphologies and soft anatomy characters of L. bracteata and a closely related congener, Lampsilis hydiana (Lea, 1838) throughout their ranges. Our results showed the presence of an undescribed species: Lampsilis bergmanni sp.n. Lampsilis bracteata and L. bergmanni sp.n. share similar shell morphologies and soft anatomy characters; however, they are genetically distinct. Geological processes, such as faulting and sea‐level changes during the Miocene to Pliocene, are likely to have facilitated diversification of Lampsilis species, resulting in isolation of L. bracteata on the Edwards Plateau and diversification between L. bergmanni sp.n. and L. hydiana. We conclude that L. bracteata range is restricted to the Colorado River basin, whereas L. bergmanni sp.n. occurs only in upstream reaches of the Guadalupe River basin. Conservation actions are warranted for both species due to their restricted distributions and potential anthropogenic threats.

中文翻译：

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一种综合方法揭示淡水贻贝（双壳类：Unionidae）中隐藏的多样性，并描述了一种新物种

主要的地质过程塑造了河流生物群的生物地理格局。美国德克萨斯州中部的爱德华兹高原展示了独特的水生群落和特有物种，包括几种淡水贻贝。Lampsilis bracteata (Gould, 1855) 是爱德华兹高原地区的特有种；然而，它与海湾沿岸河流和密西西比河流域的其他物种的系统发育关系尚不清楚。我们在整个范围内评估了 L. bracteata 和密切相关的同源物 Lampsilis hydiana (Lea, 1838) 的系统发育关系、壳形态和软解剖特征。我们的结果显示存在未描述的物种：Lampsilis bergmanni sp.n。Lampsilis bracteata 和 L. bergmanni sp.n. 具有相似的壳形态和软解剖特征；然而，它们在基因上是不同的。地质过程，例如中新世至上新世期间的断层和海平面变化，可能促进了 L. bracteata 物种的多样化，导致爱德华兹高原上 L. bracteata 的分离以及 L. bergmanni sp.n. 之间的多样化。和 L. hydiana。我们得出结论，L. bracteata 范围仅限于科罗拉多河流域，而 L. bergmanni sp.n. 仅发生在瓜达卢佩河流域的上游。由于它们的分布有限和潜在的人为威胁，因此需要对这两个物种采取保护行动。我们得出结论，L. bracteata 范围仅限于科罗拉多河流域，而 L. bergmanni sp.n. 仅发生在瓜达卢佩河流域的上游。由于它们的分布有限和潜在的人为威胁，因此需要对这两个物种采取保护行动。我们得出结论，L. bracteata 范围仅限于科罗拉多河流域，而 L. bergmanni sp.n. 仅发生在瓜达卢佩河流域的上游。由于它们的分布有限和潜在的人为威胁，因此需要对这两个物种采取保护行动。