中国西南特有翅茎草属的种间界定——基于形态学和分子系统学分析

Species Delimitation of Pterygiella(Orobanchaceae),a Genus Endemic to Southwestern China on the Basis of Morphometric and Molecular Analyses

翅茎草属(Pterygiella)是中国西南地区特有的半寄生植物。翅茎草属4种植物形态差异不显著,种的界定依据较模糊;此外,杜氏翅茎草2变种的划分依据也存在疑问。本研究选取了翅茎草属4种13个居群,通过数量性状的主成分分析和质量性状的非加权组平均法聚类分析;结合叶绿体4个片段(即atpB-rbcL、trnD-trnT、trnS-trnG和psbA-trnH)和核基因组的ITS片段研究,对该属下的种类划分作了重新界定。研究表明:翅茎草属应包括3种,即翅茎草、杜氏翅茎草和圆茎翅茎草;川滇翅茎木应作为圆茎翅茎草的变种。对杜氏翅茎草指定了后选模式,该种仅包括茎无毛的个体,而茎疏被毛的个体应归入翅茎草中。基于以上研究结果,本文提出了一个新的翅茎草属分种检索表,并做了分类修订。

Pterygiella, a genus endemic to southwestern China, belongs to hemiparasitic rhinanthoid Orobanchaceae. Since P. bartschioides was segregated as an independent genus of its own, i.e. Xizangia, the genus was treated to include four species, P. duclouxii, P. nigrescens, P. cylindrica, and P. suffruticosa. However, the discriminative characters are obscure among these species, and the delimitation of the two varieties in P. duclouxii remains prob- lematic. To revise the taxonomy of the genus, thirteen populations from the four species were collected for both mor- phometric and molecular systematic analyses. Principal component analysis （PCA） and cluster analysis via un- weighted pair-group method with an arithmetic average （UPGMA） were used. In addition, four chloroplast se- quences （i. e., atpB-rbcL, psbA-trnH, trnD-trnT and trnS-trnG） and nuclear ITS region were studied. The results showed that Pterygiella includes only three species, namely P. nigrescens, P. cluclouxii, and P. cylindrica, while P. suffruticosa should be merged into P. cylindrica as a variety. The previous delimitation of the two varieties within P. duclouxii was probably caused by imperfect analysis of morphological characters. Thus, a leetotype was designated for P. duclouxii and the plants formerly treated as P. duclouxii that bear eglandular stem hairs should be put into P.nigrescens, while the individuals with glabrous stem should remain in P. duclouxii. A new key to the three species in the genus reflecting the results of this study was presented, and a taxonomic revision was given.