Triakis attenuata Garrick, 1954 The slender smooth-hound or gollumshark (Gollum attenuatus) is a species of ground shark in the family Pseudotriakidae.

An extremely slim, plain brownish shark reaching 1.1 m (3.6 ft) in length, the slender smooth-hound can be identified by its broad, flattened head with a long, distinctively bell-shaped snout.

The growing embryo is mainly sustained by this yolk sac during gestation, though it may be additionally supplied with histotroph ("uterine milk") produced by the mother.

The International Union for Conservation of Nature (IUCN) has assessed the slender smooth-hound as Least Concern; it is taken as fishery bycatch but not in great numbers, and furthermore large portions of its range see minimal fishing activity.

The first known specimen of the slender smooth-hound was a 93 cm (37 in) long adult male collected by the trawler Maimai in December 1953, at a depth of 220 m (720 ft) off Cape Palliser on New Zealand's North Island.

It was preserved by the crew as a curiosity and given to ichthyologist Jack Garrick, who described it in a 1954 issue of the scientific journal Transactions of the Royal Society of New Zealand.

[3] 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.

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.

[2] The range of the slender smooth-hound is restricted to the upper and middle continental slope around New Zealand, including submarine features to the north such as the Three Kings Ridge, the Challenger Plateau, and the Wanganella Bank.

Generally swimming near the sea floor, this shark inhabits both soft and rocky-bottomed habitats in terrain ranging from plateaus to steep slopes.

The upper and lower jaws contain 96–99 and 108–114 rows respectively of small, very closely spaced teeth; each tooth has a narrow upright central cusp flanked by smaller cusplets on both sides.

The crown of each denticle is mounted on a short stalk and bears three horizontal ridges leading to marginal blade-like teeth, with the central tooth particularly long.