A new species of Lagenandra (Family: Araceae, Tribe: Cryptocoryneae), L. ayanae from south Western Ghats is described. The new species is related to L. kunkichirimuseumensis and L. dominicii by the foliar morphology and ecological preferences, but clearly distinct from the former by the tail in the limb, spadix appendix and reduced pistillate zone, and from the latter by the subvertically opening purple-coloured spathe limb and highly reduced pistillate part. The diagnostic morphological characters, distribution, and images of the new species are presented in this paper. A key to the known species of Lagenandra is also provided for facilitating the identification in the field.