PREMISE Cryptic species are evolutionarily distinct lineages lacking distinguishing morphological traits. Hidden diversity may be lurking in widespread species whose distributions cross phylogeographic barriers. This study investigates molecular and morphological variation in the widely distributed Caulanthus lasiophyllus (Brassicaceae) in comparison to its closest relatives. METHODS Fifty-two individuals of C. lasiophyllus from across the species' range were sequenced for the nuclear ribosomal internal transcribed spacer region (ITS) and the chloroplast trnL-F region. A subset of these samples were examined for the chloroplast ndhF gene. All 52 individuals were scored for 13 morphological traits, as well as monthly and annual climate conditions at the collection locality. Morphological and molecular results are compared with the closest relatives-C. anceps and C. flavescens-in the "Guillenia Clade." To test for polyploidy, genome size estimates were made for four populations. RESULTS Caulanthus lasiophyllus consists of two distinct lineages separated by eight ITS differences-eight times more variation than what distinguishes C. anceps and C. flavescens. Fewer variable sites were detected in trnL-F and ndhF regions, yet these data are consistent with the ITS results. The two lineages of C. lasiophyllus are geographically and climatically distinct; yet morphologically overlapping. Their genome sizes are not consistently different. CONCLUSIONS Two cryptic species within C. lasiophyllus are distinguished at the molecular, geographic, and climatic scales. They have similar genome sizes and are morphologically broadly overlapping, but an ephemeral basal leaf character may help distinguish the species.

中文翻译：

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Caulanthus lasiophyllus 中的两种加州芥末的神秘物种

前提隐性物种是进化上不同的谱系，缺乏明显的形态特征。隐藏的多样性可能潜伏在分布跨越系统地理障碍的广泛物种中。本研究调查了广泛分布的 Caulanthus lasiophyllus（十字花科）与其最亲缘关系的分子和形态变异。方法 对来自该物种范围的 52 个 C. lasiophyllus 个体进行了核核糖体内部转录间隔区 (ITS) 和叶绿体 trnL-F 区的测序。检查这些样品的一个子集的叶绿体 ndhF 基因。对所有 52 个人的 13 个形态特征以及收集地点的月度和年度气候条件进行评分。将形态和分子结果与最近的亲属-C 进行比较。anceps 和 C. flavescens-在“Guillenia Clade”中。为了测试多倍性，对四个种群进行了基因组大小估计。结果 Caulanthus lasiophyllus 由两个不同的谱系组成，这些谱系被八个 ITS 差异分隔 - 比区分 C. anceps 和 C. flavescens 的变异多八倍。在 trnL-F 和 ndhF 区域检测到较少的可变位点，但这些数据与 ITS 结果一致。C. lasiophyllus 的两个谱系在地理和气候上是不同的；但在形态上重叠。它们的基因组大小并非始终不同。结论 C. lasiophyllus 中的两个隐匿物种在分子、地理和气候尺度上是有区别的。