Taxonomic revision of the bamboo genus Schizostachyum (Bambusoideae: Melocanninae) in Thailand, with two new species and five new records, lectotypifications and nomenclatural corrections

There is ongoing discovery of new bamboo species and records in the Thai–Indo-Chinese region. As part of this work, the taxonomic documentation of the bamboo genus Schizostachyum requires improvement in its native distribution ranges, especially in Thailand. This study, for the first time, delivered a taxonomic revision of Thai Schizostachyum to provide an updated account of its species diversity. The circumscription of the genus Schizostachyum was interpreted in a broad sense includes Neohouzeaua, Teinostachyum and some species of Cephalostachyum, based on previous molecular phylogenetic studies. Species enumeration of Schizostachyum in Thailand is updated to include 15 species, of which, two are new species (S. kohchangense and S. nigrum) and four are official new records (S. cambodianum, S. chinense, S. helferi and S. strictum) for Thailand. Merely five species were previously reported from Thailand, which is only a third of the number of Thai Schizostachyum species documented in this study, of a global total of approximately 60 species. The taxonomic revision of Schizostachyum presented here provides a new key to species. Lectotypifications were made for species S. brachycladum, S. chinensis, S. grande, and S. zollingeri. An epitype was chosen to supplement the holotype of S. helferi. Morphological and nomenclatural notes are included to elucidate range of variation useful for more precise species identification and increase taxonomic stability, respectively. The analyses of conservation status assessments were performed to fulfill global-scale IUCN Redlist scheme.