The taxonomic status of Dichaea tenuifolia Schltr. is revised, the species is lectotypified and D. undulifolia Dodson from Ecuador is reduced in synonymy under the former taxon. Populations of Costa Rican Dichaea with thin-textured leaves and smooth ovary, previously included under D. tenuifolia, are recognized as a distinct species, hereafter described and illustrated as D. viridula Pupulin. Dichaea viridula may be distinguished from its closest relative, D. tenuifolia, by the shorter inflorescence, the flowers approximately half in size, the elliptic-lanceolate sepals (vs. narrowly oblong-ligulate), the petals only slightly narrowed at the base, the thick margins of the lip claw, the much shorter apical lobe of the lip, the green sepals and petals, and the white lip.