Aceros subrificollis occurs in south-east Myanmar, west, south-west and extreme southern Thailand and northern Peninsular Malaysia. All previous records from northern Myanmar, India and Sumatra were the result of misidentifications. Historically described as relatively common to very abundant in Myanmar, there have been no recent records and it appears to have undergone a rapid decline, at least in the Sittang valley. In 1993, the Thai population was estimated at