Venomous lizards Venomous lizards include the following: Gila monster (Heloderma suspectum), present in the southwestern US and Mexico Beaded lizard (H horridum) of Mexico The complex venom of these lizards contains serotonin, arginine esterase, hyaluronidase, phospholipase A2, and ≥ 1 salivary kallikreins but lacks neurotoxic components or coagulopathic enzymes.