豆科紫藤族狹義雞血藤屬與近緣群之譜系分類研究

Abstract

廣義雞血藤屬 (Callerya s. l.) 隸屬於豆科 (Fabaceae) 中蝶形花亞科 (Papilionoideae)，其屬內物種多為木質藤本植物，分布於中國南部至澳洲東部。過往分子研究顯示雞血藤支系 (Callerya clade) 不為單系群，包含紫藤屬 (Wisteria)、絹絲花屬 (Afgekia)、Endosamara屬及Millettia japonica。近期分子譜系研究將本群植物拆分為許多小屬，新定義狹義之雞血藤屬 (Callerya s. str.) 則限縮為分布於中國中南部、臺灣、中南半島及印度北方之種類，以中國為該屬之分布與多樣性中心。本群植物較重要的分類文獻為Schot (1994) 以外部形態特徵所進行之分類處理，將中國產部分雞血藤物種合併為灰毛雞血藤 (Callerya cinerea)，並認為該物種為種複合群 (species complex)。本複合群內物種之譜系關係在前述的分子研究中尚未釐清，此外，許多形態相似物種之學名處理仍存在不少爭議。本研究對狹義雞血藤屬與鄰近類群進行分類研究，選取料材來自中國、臺灣、泰國、越南、印度及澳洲之植物樣本，以核酸內轉錄間隔區 (internal transcribed spacer, ITS) 序列建構親緣關係樹，另外以MIG-seq方法及外部形態特徵觀察，對狹義雞血藤屬內種複合群相關種類進行細部分析與分類探討。結果顯示，以核基因ITS片段建構之親緣關係樹支持先前分類處理，但此分子標記無法釐清灰毛雞血藤複合群內之親緣關係。MIG-seq序列建構之譜系關係樹顯示，狹義雞血藤屬由6個具有高支持度的支系所組成，且灰毛雞血藤複合群物種的地理分布範圍和親緣關係間具有相關。形態特徵觀察部分，結果顯示花序、苞片及小苞片形態能作為灰毛雞血藤複合群內之鑑別特徵。本研究以分子親緣分群結果，並結合形態特徵觀察，確認狹義雞血藤屬內包含7個物種，為C. bonatiana、C. cochinchinensis、C. nitida、C. dielsiana、C. cinerea、C. dorwardii及一新種C. wuningensis。

Callerya Endl. (Callerya s.l.), a genus belongs to the largest subfamily Papilionoideae in Fabaceae, comprised mostly woody liana species distributing from southern part of China to eastern Australia. Previous phylogenetic studies unambiguously revealed that the Callerya clade was not monophyly, but consisted of species from Callerya, Wisteria, Afgekia, Endosamara, and Millettia japonica. Based on phylogenetic evidence, the latest revision of the Callerya clade divided genus Callerya into ten genera and reduced Callerya into a smaller and narrower genus. Since then, Callerya s. str. only comprised species from south-central China, Taiwan, indochina to northern India, with China served as biodiversity hotspot of the genus. Schot carried out a significant revision work in 1994. According to morphological characteristics, Schot united nine Chinese species that shared series of variations into a variable species, Callerya cinerea, and recognized the Callerya cinerea species complex. In the previous study, the phylogenetic relationships within taxa of C. cinerea complex still remained unclear. Also, scientific names of species with akin morphologies were still in debate. To reconfirm the recent taxonomic treatment, internal transcribed spacer (ITS) sequences from samples of southern China, Taiwan, Thailand, Vietnam, Indonesia and Australia are used to construct the phylogenetic relationships within the Callerya clade. Furthermore, in an effort to unmask phylogenetic relationships among complex species, MIG-seq and morphological observation are performed. Phylogeny of nrITS sequences supports previous treatment, but fails to distinguish the relationships within complex taxa. Analysis of MIG-seq results reveals that Callerya s. str. comprises six robust clades. Phylogeny also indicates that three complex species (C. dielsiana, C. cinerea, C. dorwardii) have different distribution ranges. Additionally, types of inflorescence, shapes of floral bract and stipule can be used to discriminate taxa within C. cinerea-complex. In conclusion, the morphological and phylogenetic results suggest that Callerya s. str. comprises seven species, including C. bonatiana, C. cochinchinensis, C. nitida, C. dielsiana, C. cinerea, C. dorwardii and one new species C. wuningensis.