Abstract
Phylogenetic relationships among the members of the epiphytic genus Yakushimabryum H. Akiyama et al. and related genera (Pylaisiadelphaceae) were studied using cpDNA (rbcL, rps4, and trnL-F) gene sequences as well as morphological features. Present analyses (1) suggested the presence of three clades in the Pylaisiadelphaceae and Sematophyllaceae (Pylaisiadelphaceae s. str., Sematophyllaceae s. str. + Heterophyllioideae, and Clastobryum), and (2) confirmed the distinctive generic status of Yakushimabryum from other members of the family. One new genus Orientobryum H. Akiyama and two new species O. ovalifolium H. Akiyama and Y. brevigemmium H. Akiyama were recognized and described. In addition, a close inter-relationship of Pseudotrismegistia undulata (Broth. & Yasuda) H. Akiyama & Tsubota and Heterophyllium amblystegum (Mitt.) J. Yu et al. (= Mastopoma subfiliferum Horik. & Ando) was confirmed. Four new combinations, O. oligonema (Cardot & P. de la Varde) H. Akiyama (≡ Clastobryum oligonema Cardot & P. de la Varde), Y. subintegrum (P. Tixier) H. Akiyama (≡ Aptychella subintegra P. Tixier), Y. tonkinense (Broth.) H. Akiyama (≡ Clastobryum tonkinense Broth. & Paris), and Pseudotrismegistia amblystega (Mitt.) H. Akiyama (≡ Stereodon amblystegus Mitt.) were proposed.
