It is native to the vicinity of the River Mekong in southeastern Asia and may have more than 500 segments and grow to a length of 2.9 m (10 ft).

[3] The type specimen was one metre long and 8 mm (0.3 in) wide at the broadest point (segment 5).

[1] The type specimen was recorded as being from "Ban Leum on Mekong River, Annam".

This was mistakenly believed to refer to a village in Central Vietnam well away from the River Mekong, but it has been found that "Ban leum" means "[I] forget the place" in the local dialect, and the type locality is thought to be in Thailand or Laos.

The river forms a delta at that point and contains extensive mud and sand flats and embankments where the worms live.