The discovery of Eastern Pacific black ghostshark Hydrolagus melanophasma is notable for a number of reasons. It is the first new species of cartilaginous fish—i.e fish whose skeletons are made entirely of cartilage, such as sharks, rays, and skate—to be described in California water since 1947. It is also a representative of an ancient and little-known group of fish.
The first individual of the new species was collected sometimes in the 1960s, however it went unnamed for decades because its taxonomic relationships were hazy Currently, there are nine preserved specimens of the species, as well as video footage of a living Eastern Pacific black ghostshark taken by a deep-water submersible in the Sea of Cortez..
 This is an Eastern Pacific black ghostshark (Hydrolagus melanophasma), a new species from California and Baja California. Photo courtesy of: MBARI. |
Ghostsharks are not sharks, but are one of the oldest and strangest groups of fish in the world. While they go by a number of names—chimaeras, ratfish, and rabbitfish—the ghostsharks closest living relatives are sharks, from which they branched off some 400 million years ago.
There are a few key attributes that make the ghostshark different from their more famous relatives. For example, male ghostsharks sport retractable sexual appendages on their forehead and in front of their pelvic fins. Ghostsharks also possess only a singlge pair of gills and grinding teeth plates that resemble rabbit’s incisors, hence the nickname ‘rabbitfish’. While ghostsharks are abundant and diverse in the fossil record, today they are mostly consigned to deep waters where they have long avoided scientific attention. In 2006 two new species of ghostsharks were discovered off the Galapagos Islands.
The Eastern Pacific black ghostshark haunts the deep waters from the coast of Southern California, along the western coast of Baja California to the Sea of Cortez.
The official description of the new species was published this month in Zootaxa.
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