A dicephalic yellow anaconda snake, Eunectes notaeus (Serpentes: Boidae), from Southern Pantanal, Brazil

We describe a case of dicephalism in a yellow anaconda snake, Eunectes notaeus, from southern Pantanal, Brazil. The specimen exhibits two heads and two long necks, which are united on the anterior third of the body. Two hearts, three lungs, two livers, and two stomachs are also present. The left heart is larger and more cranial than the right heart although they are in the normal position. Radiographs revealed approximately 64 vertebrae in the right neck, 57 in the left neck, eight in the fusion zone, 202 in the trunk, and 52 in the tail. According to the classification adopted in the present study the specimen herein described is a proarchodichotomous specimen. This is the first record of dicephalism in Eunectes. Further, this snake represents the 28th documented case of dicephalism within the family Boidae and the 1088th case in snakes.