Morphological variations of Macromitrium sulcatum (Hook.) Brid. (Musci: Orthotrichaceae), with its four new synonyms supported by molecular data

Macromitrium sulcatum (Hook.) Brid. is widely distributed in sub-Saharan Africa, South Asia, Indochina, Southeast Asia and Yunnan province of China. Our examination of its type and ordinary specimens showed that the species highly varied in the outline, basal cells, apical cells and upper margins of its branch leaves. On the phylogenetic tree based on trnL-F, trnG and ITS2, seventeen samples formed a strongly supported clade, which were morphologically associated with the types of M. sulcatum and its previous synonyms including M. seriatum Paris & Broth., M. ceylanicum Mitt., M. belangeri Müll. Hal. and M. bequaertii Thér. & Naveau, as well as those of M. lorifolium Paris & Broth., M. muellerianum Mitt., M. pseudoramentosum Herzog and M. turgidum Dixon. In this study, we compared the types and ordinary specimens of these species and found that the variations of the later four species fall within the morphological variation range of M. sulcatum. Therefore, we treated them as new synonyms of M. sulcatum.