Data from: Phylogeny of the Stachys coccinea (Lamiaceae) complex based on molecular and morphological data

One of the largest genera within the Lamiaceae, Stachys, is in extreme need of taxonomic revision due to its demonstrated phylogenetic polyphyly. Among the New World Stachys, a group of seven species belonging to the Stachys coccinea complex is widely distributed in Mexico, where four of the species in this complex are considered endemic. The members of this complex are characterized by having large and red, orange, or purple corollas. The observed morphological variation, however, may insufficiently circumscribe this number of species, and an assessment combining the use of morphological and molecular data is needed. Here, we evaluated the circumscription of the Stachys coccinea complex and relationships among its members using phylogenetic analyses of chloroplast (cp) DNA sequence data and numerical analysis applied to morphological data. We found that morphological variation in this complex insufficiently circumscribed members of the complex, possibly caused by plasticity of diagnostic morphological characters. In addition, the utilized cpDNA regions, which are commonly used in plant phylogenetic reconstruction (trnL intron, trnL-F spacer, and rps16 intron sequences), render relationships among most of the species in the complex unresolved. We propose that the Stachys coccinea complex be recircumscribed, reducing the number of members to three species: Stachys coccinea, S. lindenii, and S. albotomentosa, keeping the original circumscription of these species and including S. pacifica, S. manantlanensis, S. torresii, and S. jaimehintonii as varieties of S. coccinea.

唇形科（Lamiaceae）最大的属之一水苏属（Stachys）因被证实存在系统发育复系（phylogenetic polyphyly）而亟需开展分类学修订。在新大陆分布的水苏属类群中，隶属于红花水苏类群（Stachys coccinea complex）的7个物种广泛分布于墨西哥，其中该类群内有4个物种被认为是墨西哥特有种。该类群成员以具大型红色、橙色或紫色花冠（corollas）为典型特征。然而，现有观测到的形态变异尚不足以精准界定该类群的物种数量，因此亟需结合形态学与分子数据开展综合评估。本研究通过叶绿体（cp）DNA序列数据的系统发育分析，以及针对形态数据的数值分析，对红花水苏类群的物种界定及其成员间的系统发育关系进行了评估。研究结果显示，该类群的形态变异不足以准确区分该类群的各成员，该现象可能由诊断性形态性状的可塑性所导致。此外，本研究所用的、常用于植物系统发育重建的cpDNA区域（trnL内含子、trnL-F间隔区及rps16内含子序列），未能有效解析该类群多数物种间的系统发育关系。本研究建议对红花水苏类群进行重新界定，将其成员缩减为3个物种：红花水苏（Stachys coccinea）、林登水苏（S. lindenii）以及白毛水苏（S. albotomentosa），保留这三个物种的原始界定范畴，并将S. pacifica、S. manantlanensis、S. torresii与S. jaimehintonii归为红花水苏的变种。