N.Vietnam, Bac Kan Prov., Cho Don Distr., Ban Thi Municipality, village Phia Khao, around point 22º16'10''N, 105º31'01''E at elevation 700-850 m a.s.l. (Tang Gia mountain). Primary broad-leaved evergreen closed forest on very steep slopes and cliffs near and on tops of rocky ridge composed with solid marble-like stratified limestone. Epiphyte on high trees. Flowers: tepals dull olive-yellowish, lip from deep violet-purple to dull olive-yellowish with brown-purple marks. Common.