Additions to the orchid flora of Laos and taxonomic notes on orchids of the Indo-Burma region

The following nine new additions to the orchid flora of Laos PDR are reported based on surveys in the country conducted during the period 2012-2017: Bulbophyllum alcicorne, B. meson, Coelogyne suaveolens, Cyrtosia nana, Dendrobium phuketense, Oberonia rhizoides, Phaius columnaris, Thelasis khasiana and Zeuxine longilabris. The taxonomy of a further 15 orchid taxa (Bulbophyllum guttulatum, B. moniliforme, B. sarcophyllum, B. scabratum, B. seidenfadenii, B. tipula, Cleisostoma lecongkietii, Coelogyne ovalis, Dendrobium chapaense, D. crepidatum, D. wattii, Habenaria gibsonii var. foetida, H. malintana, Luisia zeylanica and Phalaenopsis pulcherrima) native to Laos or adjacent countries is reviewed, resulting in the synonymisation of 20 names. In addition, new combinations are made for Grosourdya vietnamica, Luisia sonii and Holcoglossum gaoligongense to bring them in line with recent changes in the classification of the orchid family.