The 2-foot-long, striking black-and-yellow snake with horn-like scales above its eyes has been named Matilda's horned viper, the society said in a release Monday.
The discovery has been published in journal Zootaxa but the authors of the research study say they are keeping the exact location of the new species a secret since the snake could be of interest to illegal pet collectors.
The snake's habitat of just a few square miles is already severely degraded by logging and charcoal manufacture, they said.
The species is expected to be classified as critically endangered, and researchers say they have already established a small captive breeding colony.
The species has been named Atheris matildae after the daughter of study co-author Tim Davenport, director of society's Tanzania program, the release said.