Abstract

The genus Rhynchotechum (Gesneriaceae) in Taiwan is revised based on a critical morphological study. Three species and one form are recognized. A new species, Rhynchotechum brevipedunculatum J. C. Wang sp. nov., is here described from Taiwan. After comparing with R. discolor in detail, R. discolor var. incisum (Ohwi) Walker can be distinguished from the former only in having incised leaves. Therefore, the taxon is reduced to the rank of form and a new combination, R. discolor forma incisum (Ohwi) Hatusima ex J. C. Wang comb. nov., is proposed here. Calyx-segments shape and inflorescence patterns are shown to be the most useful characters for the classification of Taiwan species. In addition, seed coat micromorphology under scanning electron microscope displays more or less interspecific variation. The meiotic chromosome numbers of all Taiwanese taxa are counted in this paper. All taxa, of which three are determined for the first time, have the same chromosome number (n=10). A key to the taxa of this genus in Taiwan along with description, taxonomic notes, and a line drawing are provided.

中文摘要

本文依據詳細之外部形態研究結果將台灣產同蕊草屬植物(Rhynchotechum Blume)處理為三種一型：短梗同蕊草(R. brevipedunculatum)，同蕊草(R. discolor forma discolor)，羽裂同蕊草(R. discolor forma incisum)以及蓬萊同蕊草(R. formosanum)，其中短梗同蕊草為新種。根據詳細之形態研究，發現羽裂同蕊草與同蕊草除葉形外並無其他差異，故將之處理為同蕊草之一型(R. discolor forma incisum (Ohwi) Hatusima ex J. C. Wang comb. nov.)。台灣產本屬植物在外部形態方面，以葉序、葉片形態、花序類型、萼片形態等為分類的重要特徵。以掃瞄式電子顯微鏡觀察台灣產本屬植物種皮細部形態，發現各分類群大致相同，但仍有種間差異存在。本研究並檢視減數分裂之染色體數目，發現台灣產本屬植物均為n=10，其中短梗同蕊草，羽裂同蕊草以及蓬萊同蕊草之染色體數目為首次報導。

Keyword: Chromosome number, Revision, Rhynchotechum brevipedunculatum, Gesneriaceae, Taiwan.