Northern Vietnam, Ninh Binh Prov., Nho Quan Distr., Cuc Phuong Municipality, Cuc Phuong National Park, Dang locality, about 1 km WNW of Dang Forest Control point, 20°16′28′'N, 105°40′57′'. Secondary closed evergreen seasonal broad-leaved lowland forest on limestone hills at elev. about 400 m a.s.l. Epiphyte on open places on tops of hills. Flowers dirty yellowish with purple tint, lip dull yellowish with dirty purple-violet markings. Occasional.