Bothrops jararaca—known as the jararaca[4] or yarara[5]—is a highly venomous pit viper species endemic to South America in southern Brazil, Paraguay, and northern Argentina.

[6] The drugs known as angiotensin converting enzyme (ACE) inhibitors, used for the treatment of hypertension and some types of congestive heart failure, were developed from a peptide found in the venom of this species.

[4] The head scalation includes 5–12 intersupraoculars that are weakly keeled, 7–9 supralabials (usually 8) of which the second is fused with the prelacunal to form a lacunolabial, and 9–13 sublabials (usually 10–12).

The dorsal ground color is overlaid with a series of pale-edged, dark brown subtriangular or trapezoidal markings on either side of the body, the apices of which reach the vertebral line.

They are ambush predators and equipped with good camouflage; juveniles use caudal luring to attract and capture prey, making movements with the tip of the tail, which is white and appears very similar to an insect larva.

In Brazil, it is referred to as caissaca, jaraca, jaracá, jararaca, jararaca-do-rabo-branco, jararaca-do-campo, jararaca-do-cerrado, jararaca-dormideira, jararaca-dominhoca and malha-de-sapo.

[9] The lethal dose for a 60 kg adult human is 70 mg.[10] Typical envenomation symptoms include local swelling, petechiae, bruising and blistering of the affected limb, spontaneous systemic bleeding of the gums and into the skin, subconjunctival hemorrhage and incoagulable blood.

The systemic symptoms can potentially be fatal and may involve hemostatic disorders, intracranial hemorrhage, shock, and kidney failure.

[8] Thrombotic microangiopathy has also been reported, a 56 year old woman was transferred from a primary hospital seven hours after being bitten by a Bothrops jararaca in the distal left leg.