Barito River
"P. frontata" is endemic to Borneo, and restricted to the south-east of Borneo, below 3°N and east of Barito River. It was recorded in the east between the Kayan River and Banjarmasin in the south. Meanwhile, "P. f. nudifrons" was recorded from central Sarawak between the upper Rajang River and upper Batang Lupar, including Lanjak Entimau Wildlife Sanctuary.