The specific name, fuscum, is Latin for "dusky" or "dark brown".

[4] It is found in Nepal and India (Jammu & Kashmir, northern West Bengal, Uttarakhand, Sikkim, Assam, eastern Arunachal Pradesh), possibly also in Bhutan.

[2] As the common name implies, the venter is black or dark brown.

The dorsum is also black or dark brown, and may have lighter longitudinal streaks.

Males have keeled scales on their sides in the anal region.