A new species of Erythrodes Blume (Orchidaceae), E. triantherae C. L. Yeh et C. S. Leou, from Lanyu of Taiwan is described and illustrated. It is characterized by the column which is adorned with 1-3 anthers, i.e. additional 2 or 1 stamens often present on the ventral side of column and in the lip which is much shorter (4.5-5.5 mm long) and only saccate at base, not long spurred. Results of a preliminary observation on the variation of anther number, and on the development of fruits have also been noted. We also provide a new key to the species of Erythrodes in Taiwan.