Only four specimens of the elusive four-inch (ten-centimeter) pink handfish have ever been found, and all of those were collected from areas around the city of Hobart (map), on the Australian island of Tasmania.

Though no one has spotted a living pink handfish since 1999, it's taken till now for scientists to formally identify it as a unique species.

The new-species determinations were made based on a number of factors, including number of vertebrae and fin rays, coloration, the presence of scales and spines, and proportional body measurements, according to review author Daniel Gledhill of Australia's Commonwealth Scientific and Industrial Research Organisation, or CSIRO.

All of the world's 14 known species of handfish are found only in shallow, coastal waters off southeastern Australia, the review notes.

Even among the previously known species, the fish are poorly studied, the review authors add, and little is known about their biology or behavior.

(See pictures of some of the hundreds of new sea species recently found off Tasmania.)