Chironius laurenti

Chironius laurenti is a nonvenomous snake of the family Colubridae, placed in the genus Chironius, whose members are commonly called sipos or savanes. It was described in 1993 by the herpetologists James R. Dixon, John A. Wiest Jr. and José M. Cei from type specimens recovered along the Mamoré River in the Beni department of Bolivia, and it is named after the Belgian herpetologist Raymond Laurent. It is a large snake: the longest male found measured 2.15 metres in total length, including the tail, and the longest female 1.78 metres. Adults have an olive, grayish or gray-brown head, and the back varies from grayish through olive to brown, with the front of the body usually grayer and the rear two thirds of the body and tail browner. The scales under the tail are an unmarked yellow, there are 2 to 10 keeled scale rows in males and 2 to 6 in females, and 32 to 36 maxillary teeth are present. Its known range covers Beni, Cochabamba and Santa Cruz in Bolivia and Mato Grosso in Brazil; the Reptile Database also lists Acre in Brazil, calls the species partly arboreal and egg laying, and notes that a 2026 study restricted the name to populations of the Madeira River basin.