Isolation of desert springs often leads to the evolution of unique biodiversity. We investigated the taxonomy and evolutionary relationships of members of the Gammarus pecos complex, an assemblage of narrowly endemic amphipod species in the Chihuahuan Desert of the USA. Morphological and molecular phylogenetic analyses, including newly obtained COI sequences from the now-extinct type population of Gammarus desperatus, reveal the presence of two undescribed species and lead to redescription of G. desperatus. Gammarus acerbatus sp. nov. is split from G. desperatus and Gammarus balmorhea sp. nov. is split from G. hyalelloides. Each of these species is endemic to a single spring system. Speciation in the Gammarus pecos complex was likely promoted by the lineage’s ties to marine/riverine systems and geological events during the Oligocene/Miocene. The additional diversity discovered within the complex highlights the effects of both habitat and evolutionary history on the processes of speciation at local and regional spatial scales. The entire complex of at least six species is imperilled due to the narrow ranges occupied by each species and human water-use that threatens the existence of their spring habitats.

中文翻译：

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分子系统发育分析揭示了奇瓦瓦沙漠北部淡水 Gammarus（片脚类：Gammaridae）的辐射


沙漠泉水的孤立往往会导致独特的生物多样性的演变。我们研究了 Gammarus pecos 复合体成员的分类学和进化关系，Gammarus pecos 复合体是美国奇瓦瓦沙漠中狭长的特有片脚类物种的集合。形态学和分子系统发育分析，包括从现已灭绝的 Gammarus desperatus 类型种群中新获得的 COI 序列，揭示了两个未描述物种的存在，并导致对 G. desperatus 的重新描述。 Gammarus acerbatus sp.十一月是从 G. desperatus 和 Gammarus balmorhea sp. 中分离出来的。十一月是从 G. hyalelloides 中分离出来的。这些物种中的每一个都是单一泉水系统的特有物种。 Gammarus pecos复合体中的物种形成可能是由于该谱系与渐新世/中新世期间海洋/河流系统和地质事件的联系而促进的。在该复合体中发现的额外多样性凸显了栖息地和进化历史对当地和区域空间尺度物种形成过程的影响。由于每个物种占据的狭窄范围以及人类的用水威胁了它们春季栖息地的存在，至少有六个物种的整个复合体受到了威胁。