Monomorium bicolor is an abundant ant in The Gambia. It had been collected there before in around 1926 in Banjul (formerly Bathurst), and in 2007 in Kololi and on Jinack Island. It is distributed from Angola north to Sudan and from Somalia across to Senegal.
M. bicolor seems to be present in a variety of habitats, as it was found on trees, on the ground in open areas, on buildings and once scavenging from a dead fish, but was only found nesting in the ground.
M. bicolor is very similar to Monomorium dictator, but differs by being generally larger, though also variable in size, and lacking abundant setae on the anterior half of the first gastral tergite. It should have at least two erect setae on the anterior margin of the first gastral tergite, but these were lacking in all Gambian specimens. Five out of the nine specimens examined had distinct pits where the setae should have been, but all lacked setae. Nevertheless, there is no doubt that they are M. bicolor, so the hairs have perhaps rubbed off or Bolton (1987) defined the species too narrowly.