N Vietnam, Cao Bang Prov., Tra Linh Distr., Quoc Toan Municipality, vicinity of Thang Heng and Lung Tao villages near Thang Heng Lake. Remnant closed evergreen primary broad-leaved forest on steep slopes and bluffs of limestone ridges and mesas near karst lake at 500-650 m a.s.l. On shady rocky slopes and bluffs.