Lesulas have "giant blue backsides," according to John Hart, one of the researchers who was able to identify the monkeys as a new species. "Bright aquamarine buttocks and testicles. What a signal! That aquamarine blue is really a bright color in forest understory." Another species, known as the owl-faced monkey, shares this characteristic, and the two were thought to be closely related, but the lesula has "significantly larger incisors" as well as different sounds emitted and a different type of coat. Genetic research shows that the two species split from a common ancestor over two million years ago.
Hart discovered the monkey living as a sort of pet at the house of a little girl named Georgette. In the village, the monkey was simply known as "Georgette's lesula." The little girl is now 18 years old, and although the "animal was very attached to her," it disappeared a few years back.