Four new species, including two newly recorded genera of diatoms, are described from lentic habitats of Western Ghats, South India. The new species are Pleurosira indica, Spicaticribra kodaikanaliana, Urosolenia curvata and U. extensa. Pleurosira indica and Spicaticribra kodaikanaliana were collected from Kodaikanal Lake in Tamil Nadu and the two Urosolenia species are collected from Hirebhasker Dam in Karnataka, India. Pleurosira indica differs from other members of the genus by the irregularly arranged areolae and c-shaped depressions associated with the rimoportulae. Spicaticribra kodaikanaliana lacks the large central openings found in S. kingstonii, but is otherwise very similar to this North American taxon. The two new Urosolenia species, U. extensa and U. curvata, have distinct shapes to their valves, unlike other previously described species of the genus. All of these new species were observed with light and scanning electron microscopes, and we discuss their systematic positions.