Genus Gollum Compagno

Gollum Compagno, 1973, Proc. California Acad. Sci., ser. 4, 39(14): 264. Type species: Triakis attenuata Garrick, 1954, by original designation.

Definition. Distinctive carcharhiniform sharks with a firm to soft and very slender body; short, bell-shaped head; long, flattened snout, horizontal length 7–9% TL; small spiracles, 4–10 times in eye length; angular mouth with very small multicuspidate teeth (81–114 rows in jaws); dental bands comb-like near jaw angle; moderately elongate labial furrows (lower furrow subequal to or greater than length of incurrent aperture of nostril); short anterior nasal flaps (subequal to length of excurrent aperture of nostril); broad internarial space, 1.5–1.9 times nostril width; no dermal gill rakers or large oral papillae; first dorsal fin not long-based and keel-like; interdorsal ridge present; first dorsal-fin base well forward of the pelvic-fin base; second dorsal fin taller and more upright than first dorsal fin; anal-fin origin well behind second dorsal-fin origin; free rear tip of anal fin under or slightly forward of second dorsal-fin insertion; no precaudal pits; caudal peduncle relatively elongate, 8–10% TL; dorsal caudal margin short, 19–23% TL, not undulated, instead with a raised scaly ridge; enlarged lateral scales of caudal ridge semicircular, horizontally directed; coloration simple, darker dorsally than ventrally; monospondylous centra 44–53, diplospondylous centra 107–113, total centra 151–166.

Species. Gollum attenuatus (Garrick, 1954), G. suluensis sp. nov.

Remarks. The erection and initial placement of Gollum in the family Proscylliidae followed Compagno (1973), and was subsequently assigned to a new subgenus Golluminae (Compagno, 1988). However, in more recent studies (Compagno 1999; Compagno et al., 2005a, 2005b) it has been relocated to the related carcharhiniform family Pseudotriakidae . Gollum differs from the three proscylliid genera (i.e. Eridacnis Smith, Proscyllium Hilgendorf and Ctenacis Compagno) in having a deep notch on the lateral margin of the snout forward of the nostrils giving the head a bell-shaped appearance (rather more evenly rounded) when viewed dorsolaterally, and lacking gill rakers and oral papillae (Compagno, 1988). It shares the family Pseudotriakidae with the monotypic genus Pseudotriakis Capello, which differs from Gollum in having a soft stocky body (firmer and more slender), a very long, keel-like first dorsal fin (relatively taller and much shorter based), and a much shorter caudal peduncle.