Taxonomy
The velvet belly was originally described as Squalus spinax by Swedish natural historian Carl Linnaeus, known as the "father of taxonomy", in the 1758 tenth edition of Systema Naturae. He did not designate a type specimen; the specific epithet spinax is in reference to the spiny dorsal fins. This species was later moved to the genus Etmopterus via the synonymy of Constantine Samuel Rafinesque's Etmopterus aculeatus with Squalus spinax.
The velvet belly is grouped with the Caribbean lanternshark (E. hillianus), fringefin lanternshark (E. schultzi), brown lanternshark (E. unicolor), broadbanded lanternshark (E. gracilispinis), combtooth lanternshark (E. decacuspidatus), and dwarf lanternshark (E. perryi) in having irregularly arranged, needle-shaped dermal denticles. Its common name comes from this shark's black ventral surface, which is sharply delineated from the rest of its body like a patch of velvet.
Read more about this topic: Velvet Belly Lanternshark