Biodiversity is being lost at an alarming rate, but the rate of this loss is likely to be underestimated as a result of a deficit in taxonomic knowledge (i.e. the Linnean shortfall). This knowledge gap is more extensive for morphologically indistinct taxa. The advancement of molecular techniques and delimitation methods has facilitated the identification of such cryptic species, but a majority of these taxa remain undescribed. To investigate the effects of taxonomic uncertainty on understanding of biodiversity, we applied the general lineage concept of species to an amphipod species complex, the Gammaruslacustris lineage that occupies springs of the northern Chihuahuan Desert, which is emerging in contemporary times. We investigated species boundaries using a validation-based approach and examined genetic structure of the lineage using a suite of microsatellite markers to identify independently evolving metapopulations. Our results show that each spring contains a genetically distinct population that is geographically isolated from other springs, suggesting evolutionary independence and status as separate species. Additionally, we observed subtle interspecific morphological variation among the putative species. We used multiple lines of evidence to formally describe four new species (Gammarus langi sp. nov., G. percalacustris sp. nov., G. colei sp. nov. and G. malpaisensis sp. nov.) endemic to the northern Chihuahuan Desert. Cryptic speciation is likely to be high in other aquatic taxa within these ecosystems, and across arid landscapes throughout North America and elsewhere, suggesting that the magnitude of the Linnean shortfall is currently underestimated in desert springs worldwide.

中文翻译：

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解决神秘物种复合体中的林奈问题

生物多样性正在以惊人的速度丧失，但由于分类学知识的不足（即林奈的不足），这种丧失的速度很可能被低估。对于形态上不明确的分类群，这种知识差距更为广泛。分子技术和定界方法的进步促进了此类神秘物种的鉴定，但这些分类群中的大多数仍未被描述。为了研究分类学不确定性对理解生物多样性的影响，我们将物种的一般谱系概念应用于片脚类物种复合体Gammarus lacustris占据当代新兴的奇瓦瓦沙漠北部泉源的血统。我们使用基于验证的方法调查了物种边界，并使用一组微卫星标记检查了谱系的遗传结构，以识别独立进化的元群。我们的结果表明，每个泉水都包含一个在地理上与其他泉水隔离的遗传上不同的种群，这表明进化独立性和作为独立物种的地位。此外，我们观察到假定物种之间存在细微的种间形态变异。我们使用多条证据来正式描述四个新物种（Gammarus langi sp. nov.、G. percalacustris sp. nov.、G. colei sp. nov.和G. malpaisensis sp。十一月 ) 奇瓦瓦沙漠北部的特有种。在这些生态系统内的其他水生分类群中以及整个北美和其他地方的干旱景观中，隐性物种形成可能很高，这表明目前全世界沙漠泉中林奈短缺的程度被低估了。