Chironius flavolineatus, also known as Boettger's sipo, is a vine snake species in the family Colubridae, endemic to savannas and semiarboreal biomes in Brazil, and much of South America.

The Chironius flavolineatus's distinguishing trait is a yellow or cream white vertebral stripe that extends for nearly the entire length of the snake's body.

The back of the Chironius flavolineatus's head ranges in color from tan to brown and is distinct from the superior third of the body, which is black or dark gray.

The Chironius flavolineatus usually has a single posterior temporalis muscle, a divided cloacal shield, and white, unpigmented ventral and subcaudal scales.

The differences in eye diameter, which has been observed in other members of the Chironius genus that live in the Atlantic Forests, is often linked to male-exclusive activities such as searching for females.

This speculation has been reinforced in natural studies, which show Chironius flavolineatus members foraging on the ground before resting at night in above-ground vegetation.

Chironius flavolineatus is commonly found in areas that are between 100 and 400 meters above sea level in biomes such as semiarboreal forests and grass steppes.

[7] Courtship behavior was recorded in October during the rainy season, and data shows that mating in Chironius occurs at least in two periods of the year.