Pterocymbium R. Br (Sterculioideae, Malvaceae), a genus new to China and suggestions for conservation

Abstract

The genus Pterocymbium R. Br. is new to China, and the remarkable discovery is reported in the present study. P. macranthum Kosterm., a winged-boot tree published in 1962, has recently been spotted in the border regions of China and Laos. The main detailed anatomical characteristics of the flower are photographed, and supplementary descriptions of the species are made based on fresh materials, herbarium collections, and available literature. Historically, the tree is only recorded in Southcentral Myanmar to Northern and Southwestern Thailand. The new record in the present study extends the known geographical range of P. macranthum to the northern edge of the Asian tropics and contributes to the knowledge of the tree flora both in China and Southeast Asia. Aided by drones, the population size of China has been rapidly assessed, and ca. 1000 individuals were recognized from high-resolution photos in ca. 2000 ha area. Herbaria were prepared and deposited in the herbarium of Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences (HITBC).