[2] McCosker later requested for Dominique Didier, a biology professor at Millersville University, to assist with describing the new species.

[3] It was described by Lewis A. K. Barnett, Dominique Didier, Douglas Long, and David A. Ebert in October 2006,[4] and the finding of the species was published in the scientific journal Zootaxa.

[2][3] Didier said, "Determining Hydrolagus mccoskeri was a new species of ratfish wasn't difficult, but going through all the verification steps required a great deal of time.

"[3] The holotype of the species is a juvenile female, found by John McCosker, R. Grant Gilmore, and Bruce Robinson on November 17, 1995, southeast of San Cristóbal Island.

Due to the rough, rocky habitat of the species, trawling, the traditional way of collecting fish for study, was unsuitable.

Other characteristics of the species include a small head, a round snout, large green eyes, and nostrils linked to its mouth with a flap-covered groove.

[5] The Galápagos ghostshark has been observed to occur on steep slopes,[4] in areas containing stones and boulders with dispersed sand and silt.

The International Union for Conservation of Nature (IUCN) said that the species requires further studying of its population and threats before receiving an assessment.