Cosmocerca microhylae sp. nov., recovered from the rectum of a red narrow-mouthed frog, Microhyla rubra (Jerdon, 1854) (Anura: Microhylidae), collected from Bolpur in the Birbhum district of West Bengal, India, is described and figured. This species is similar to C. acanthurum, C. banyulensis, C. cruzi, C. japonica, C. kalesari, C. novaeguineae, C. ornata, C. paraguayensis, C. parva, C. podicipinus and C. travassosi in having 5 pairs of plectanes supporting preanal papillae but differs from these species by smaller size, absence of somatic papillae in females and having only one pair of adanal papillae in males and one pair postanal papillae in females. Cosmocerca microhylae sp. nov. represents 27th species assigned to the genus, and 4th species from India.