Boettger's Sipo

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. It is listed as least concern on the IUCN Red List since 2014. It is a member of the Genus Chironius which is composed of twenty-two other described snake species. It is nonvenomous, using camouflage or burrowing as a form of defense.

Description

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. On either side of the stripe, black sides that begin after the first row of scales lie anteriorly. 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. Chironinus flavolineatus also features 0-4 rows of keeled dorsal scales in its midbody and a static color pattern throughout its lifetime

Studies indicate that Chironius flavolineatus is sexually dimorphic. Adult females tend to be larger than males, with an average weight around 81 g (2.9 oz) and an approximate total length of about 1.16 m (3 ft 10 in). Adult males weigh approximately 60 g (2.1 oz) and reach a total length of around 1.10 m (3 ft 7 in). Males tend to have long tails and larger eyes than their female counterparts, while no dimorphism is seen in the head size of the sexes. The smaller size of males indicates that there is limited male to male combat for mating. 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. Females members of the Chironius flavolineatus only begin to reproduce when their body is large enough to carry their eggs. This likely creates the selective pressure that leads to females being larger than males throughout the species. The thin body and long tails of the Chironius flavolineatus indicate that they have arboreal tendencies when in savanna environments. 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.

Distribution & habitat

Chironius flavolineatus has no specific locality and has been reported in São Paulo, Amazonas, Rio Grande do Sul, Pernambuco, Rio Grande do Norte and many other regions in South America. It is found predominantly in Brazil, but is also found in Paraguay, Bolivia and Peru. 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.

Behavior and ecology