Murdannia sanjappae, a new species of dewflower plant of the dayflower family from Rutland Island, South Andaman Islands, India, is described and illustrated. This novel species is similar to M. tenuissima in not having any staminodes, but differs from it by having oblong-lanceolate leaves with cordate base, distinct peduncle, pedicel with 2–3 articulations, ovate petals, and 24–30-seeded capsules.