Chlorocebus is a genus of medium-sized primates of which seven species are currently recognized.
The seven species look very similar and were therefore formerly classified as a single species.
These seven species are:

1. Green Monkey (Chlorocebus sabaeus), found in West Africa;
2. Tantalus Monkey (Chlorocebus tantalus), found in Ghana to Sudan and south into Uganda;
3. Vervet Monkey (Chlorocebus pygerythrus), found in southern and East Africa.
4. Bale Mountains Vervet (Chlorocebus djamdjamensis), found only in Ethiopia;
5. Grivet (Chlorocebus aethiops), found in Ethiopia, Sudan, Djibouti and Eritrea;
6. Dryas Monkey (Chlorocebus dryas), found only in the Congo Basin; and
7. Malbrouck (Chlorocebus cynosuros), found in DR Congo, Angola and Zambia.

The one occurring in Gambia is the Green Monkey (Chlorocebus sabaeus).

1st photo: Kololi Beach area, Gambia, 16 August 2008
2nd & 3rd photo: Lamin Lodge area, Banjul area, Gambia, 21 August 2006