We describe a new species of the Hemidactylus acanthopholis clade from Sirumalai, an isolated massif in the Dindigul district of Tamil Nadu state, India. Hemidactylus sirumalaiensis sp. nov. can be diagnosed from all members of the prashadi group by its medium body size (SVL <95 mm), the number of dorsal tubercles rows at mid-body, the number of enlarged tubercles in paravertebral rows, the number of femoral pores and poreless scales between series of left and right femoral pores on the femoral-precloacal row in males, the number of ventral scales across the belly at mid-body and subtle colour pattern differences. The new species is the fourth member of the acanthopholis clade and 8.5–13.4 % divergent in ND2 sequence data from other members of the clade. We also provide data on additional specimens from a new locality of Hemidactylus kolliensis, previously known only from the male holotype. Hemidactylus sirumalaiensis sp. nov. is the first endemic and only the other vertebrate species described from Sirumalai massif in the last 133 years. Most rupicolous Hemidactylus species from peninsular India outside the Western Ghats are known only from a few localities and are likely to be geographically restricted in distribution, and large areas of suitable habitat remain unsurveyed, suggesting many more allied species remain to be discovered.