UNTIL RECENTLY, scientists thought South America was home to just one kind of green anaconda, the world’s heaviest snake. But a study has revealed there are two species of the reptile: Eunectes murinus, the southern green anaconda that lives in Brazil, Peru, and Bolivia, and the newly named Eunectes akayima, or northern green anaconda. The latter is found in Ecuador, Venezuela, Trinidad, Guyana, Suriname, and Colombia. Nearly identical in appearance but with distinct genetics, both snakes also dwell in French Guiana, sometimes on opposite banks of the same river. Yet they never interbreed. According to study co-author Bryan Fry, a National Geographic Explorer and biologist at the University of Queensland in Australia, they’re more than 5 percent different genetically. To put that into context, we’re less than 3 percent different from…