We describe a new species of the Gonocephalus megalepis group and provide new morphological and distribution data for the three other species of the group. The combination of a wide gap between the nuchal and dorsal crests, distinctly heterogenous scales on the flanks, a gular crest, two large tubercular scales ventral to the tympanum, and 97–125 scales around midbody will distinguish the new species from all congeners. The new species occurs above 1100 m on mountains of Sumatra's southern Bukit Barisan Range below 3°S latitude. Head scales of some specimens were infested by a green, filamentous symbiont, which we tentatively identify as an epizoic plant. Gravid females develop crimson stripes on their gular pouch as an apparent social signal.