It is endemic to southern Tanzania and is only known from the Kihansi–Ulanga River floodplain from elevations of 200–500 m (660–1,640 ft) above sea level.

[1][3] It is named after Allen Rees, a principal game warden for the Tanzanian Wildlife Department[4] who collected the type series.

[2] The holotype, an adult male, measures 57 mm (2.2 in) in snout–urostyle length.

Three adult female paratypes measure 55–60 mm (2.2–2.4 in) in snout–urostyle length.

It is present in the poorly protected Kilombero Game Controlled Area.