| Summary: | 碩士 === 國立臺灣大學 === 植物病理與微生物學研究所 === 96 === Taxonomy and biology of the lichen genus Usnea in Taiwan were studied based on morphological, chemical, cultural traits, and molecular analyses. We studied over 300 specimens collected from the Central Mountain Range, Snow Mountain Range, Jade Mountain Range, Ali Mountain Range and Coastal Mountain Range from 2006 to 2008. Twenty-two species were recognized, including U. aciculifera, U. baileyi, U. bismolliuscula, U. ceratina, U. cornuta, U. diffracta, U. fragilescens, U. glabrata, U. himalayana, U. longissima, U. malmei, U. masudana, U. nidifica, U. orientalis, U. pangiana, U. pectinata, U. pseudogatai, U. rubicunda, U. rubrotincta, U. shimadai, U. sinensis, and U. trichodeoides. More than 40 lichen substances were found by high performance liquid chromatography (HPLC). The chemical constitutions supported the identification of Usnea species. It was found that U. longissima had the highest usnic acid contents (3.31%). In cultural studies, the best temperature for the growth of U. orientalis was 20℃ (1.14-1.87 mm / month), and it grew better on 4% agar than on 2% agar. Adding usnic acid to the cultural media did not affect the growth of U. orientalis. Molecular analyses based on sequences of ITS (internal transcribed spacer) of ribosomal RNA genes supported the separation of U. rubicunda and U. rubrotincta. Usnea himalayana and U. nidifica could be considered conspecific due to the fact that their intermediate forms exist among our collections and that their DNA sequences were highly similar. The results also showed that U. orientalis-U. pygmoidea probably represent species pairs of teleomorph-anamorphs connection. Usnea species in Taiwan frequently grow on plants of Pinaceae (22%), Rosaceae (15%) and Betulaceae (12%). Their altitudinal distribution was within the range 800-3400 m. Usnea himalayana, U. longissima, and U. trichodeoides are distributed at higher elevations, whereas U. baileyi, U. bismolliuscula, U. pectinata, U. rubicunda, and U. rubrotincta are at lower elevations.
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