Slender smooth-hound journal "Transactions of the Royal Society of New Zealand". Garrick named the species "Triakis attenuata", in reference to its extremely slender ("attenuate") body. In 1973, Leonard Compagno proposed a separate genus for the slender smooth-hound: "Gollum", after the character in J. R. R. Tolkien's "The Lord of the Rings", "to whom this shark bears some resemblance in form and habits." He placed "Gollum" with the finback catsharks (Proscylliidae), but also noted its many anatomical similarities to the false catshark ("Pseudotriakis microdon"). At the time, Compagno chose to maintain "Pseudotriakis" as the sole member of the family Pseudotriakidae because of its
Slender smooth-hound numerous unique traits. More recently, he and other taxonomists have increasingly tended to group "Gollum" and "Pseudotriakis" together in the family Pseudotriakidae. This arrangement was corroborated by a 2006 phylogenetic study by Juan Andrés López and colleagues, which found that the two genera have a high degree of genetic similarity across four protein-coding genes and form a natural clade apart from "Proscyllium". An additional species of "Gollum" has now been described, and there is at least one additional species yet to be described. The range of the slender smooth-hound is restricted to the upper and middle continental slope around New