Molecular phylogeny and taxonomic revision of the genus Diastatea (Campanulaceae: Lobelioideae)

Diastatea (Campanulaceae-Lobelioideae) is a genus of small, herbaceous annuals found mostly in Mexico. Differences in the number of recognized species in the historical treatments, and the lack of a phylogeny, suggested that a revision of the genus was necessary. Species boundaries and species level relationships were tested based on a sampling of nearly 50 individuals. Sequences of the chloroplast spacer regions, atpB-rbcL and ndhF-rpl32, as well as the ITS, were generated and then analyzed using maximum likelihood and Bayesian inference methods. The analyses of the combined dataset produced congruent topologies. Two strongly supported clades of Diastatea are newly recognized as subgenera in the taxonomic treatment. Diastatea Scheidw. subg. Diastatea and Diastatea subg. Angustifolia E.P.Johnson and T.J.Ayers can be distinguished morphologically by leaf shape and pubescence, hypanthium shape, and the presence or absence of a gibbous projection on the ventral side of the corolla. A morph...歧沙参属（*Diastatea*，桔梗科半边莲亚科Campanulaceae-Lobelioideae）是一类小型一年生草本植物类群，主要分布于墨西哥境内。历史分类研究中，关于该属公认物种数量的分歧，加之缺乏系统发育研究，表明该属亟需开展分类修订。本研究基于近50份个体的取样，对该属的物种界定及物种间亲缘关系进行了检验。研究扩增并测序了叶绿体间隔区atpB-rbcL、ndhF-rpl32以及核糖体内部转录间隔区（ITS，Internal Transcribed Spacer）的序列，随后采用最大似然法与贝叶斯推断法进行系统发育分析。联合数据集的分析得到了一致的拓扑结构。在本次分类处理中，歧沙参属的两个高支持率演化支被新确立为亚属：歧沙参原亚属（*Diastatea* Scheidw. subg. *Diastatea*）与狭叶歧沙参亚属（*Diastatea* subg. *Angustifolia* E.P.Johnson & T.J.Ayers），二者可通过叶形与毛被、花托筒形状，以及花冠腹面是否具囊状突起等形态特征加以区分。一项形态学……