For the first time since 1947, a new species of cartilaginous fish has been described from Californian waters. The new species – Hydrolagus melanophasma – belongs to a group of sharks known as Chimaeras or ghostsharks.

Chimaeras are fairly closely related to the true sharks, but their evolutionary lineage branched off from the true sharks nearly 400 million years ago. Just like sharks, ghostsharks have cartilage skeletons instead of bony skeletons and they carry out internal fertilization using claspers. Unlike the true sharks however, males of the Chimaera group are fitted with retractable sexual appendages on the forehead and in front of the pelvic fins. Most known species also have a venomous spine in front of the dorsal fin.

The new species, the Eastern Pacific black ghostshark, was caught and preserved as early as the 1960s but hasn’t been formally named and described until know since its taxonomic relationships with other Chimaeras remained unclear. It is now placed in the genus Hydrolagus – the water rabbits – a genus named after the grinding tooth plates used by its members; plates somewhat similar to the teeth of a rabbit.

You can find out more about Hydrolagus melanophasma in the September issue of the journal Zootaxa. The article in which the new species was described is the result of the combined efforts of a team of scientists, including Academy Research Associates David Ebert and Douglas J. Long, graduate student Kelsey James from the Moss Landing Marine Laboratories, and Dominique Didier from Millersville University in Pennsylvania.