摘要
Mitrastemonaceae (帽蕊草科) 為亞洲-美洲間斷分布的全寄生性植物類群，科下僅具Mitrastemon一屬。Mitrastemon屬先後有六個學名被發表，一個為美洲分布的M. matudae，其他則分布於亞洲。因亞洲物種間的鑑別特徵較不明確，且具有連續變異的疑慮，因此目前普遍接受將亞洲分布之物種合併為M. yamamotoi一種的分類處理。然而在臺灣發現的個體仍有較大的形態差異，並可依形態區分為M. kanehirae與M. kawasasakii兩個物種，且此一分類觀點仍廣泛被臺灣的分類學者使用，也使得臺灣與其他亞洲各地分類標準不一的窘境。 因此本研究欲以主成分分析比較形態特徵，並以nrITS、rrn16、rrn23與nad1等作為分子標記進行分子譜系分析，檢視現今帽蕊草科下的分類觀點是否合適。分子譜系的結果顯示，美洲與亞洲的帽蕊草科植物為兩個不同的支序，而亞洲的族群又可分成兩個高支持度的單系群，意即亞洲族群已具有遺傳分化。形態主成分分系結果也吻合分子譜系之結果，因此本研究不支持現今將亞洲分布之物種合併為M. yamamotoi一種的分類處理。 依據分子與形態證據，並對應已發表學名之形態，應將帽蕊草科帽蕊草屬分為三個物種：M. matudae (松田氏帽蕊草)、M. yamamotoi (帽蕊草) 以及M. kawasasakii (川上氏帽蕊草/臺灣奴草)。原先於臺灣植物誌第二版中，被視為特有種、於臺灣狹隘分布的M. kanehirae (多鱗帽蕊草/菱形奴草) 為M. yamamotoi之同物異名，而同樣被視為特有種的M. kawasasakii則不僅分布於臺灣，即臺灣現有之兩種帽蕊草科植物皆非臺灣特有種。
並列摘要
Mitrastemon is a genus of root holoparasitic plant with amphi-Pacific distribution. Based on the molecular phylogenetic analysis, Mitrastemon was separated from Rafflesiaceae and formed a monotypic family within Ericales: Mitrastemonaceae. There were six species of Mitrastemon published, one from central America (M. matudae) and the others from Asia. Because the characters to identify these species are uncertain and there might be continuous variations, these species from Asia were combined to a single species: M. yamamotoi. However, there are obviously morphological variation amount the individuals found in Taiwan, and these individuals are identified to two species, M. kanehirae and M. kawasasakii. This conflict of taxonomic treatments leads to the problems of identification of this taxon. Therefore, we will test whether the taxonomic treatments of genus Mitrastemon nowadays is suitable or not by principal component analysis (PCA) of morphological traits and molecular phylogenetic analaysis. Phylogenetic tree using nrITS, rrn16, ptITS, rrn23 and nad1 as markers, samples from central America and Asia are separated into two clades, and there are two monophyletic groups within the samples from Asia. The result of PCA match to the result of molecular phylogeny. That is, there are distinct variation between species found in Asia. Thence, this work rejects the taxonomic treatment that combined all species as M. yamamotoi in Asia. In conclusion, according to the morphological traits and molecular phylogeny, there are three species confirmed within the genus Mitrastemon: M. matudae, M. yamamotoi, and M. kawasasakii. M. kanehirae should be synonymized under M. yamamoto. Both M. kanehirae and M. kawasasakii are not endemic species in Taiwan.
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