Hypsiglena unaocularus

Description

Hypsiglena unaocularus, commonly known as the Islas Revillagigedo night snake or Clarión night snake, is a species of small colubrid snake endemic to Clarion Island, initially described from a single specimen collected by William Beebe in 1936. During the next several decades, scientists were unable to detect any trace of the snake in their field studies. After an intensive search in 2013, a team of scientist identified 11 snakes that matched the original description of the species. They conducted a series of DNA tests to confirm that the Islas Revillagigedo nightsnake, formerly viewed as the subspecies Hypsiglena torquata unaocularis, is genetically distinct from related mainland snakes and should be recognized as a full species. While never formally declared extinct, this species remained absent from scientific literature due to two main factors: its home on Clarion is extremely remote and only accessible by military escort, significantly restricting the number of biologists who can access this area, and the snake’s secretive, nocturnal behavior and dark coloration make it difficult to detect in the field. Because of the lack of follow-up sightings, scientists long presumed that Beebe had provided an incorrect locality for his specimen.