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Vertebrae: 132-139. Diagnosis: A small five-gilled sawshark distinguished from its congeners by having the following characteristics: the presence of two rows of enlarged pre-barbel pits on the rostral ventral surface; rostral barbels closer to mouth than snout tip; base of large rostral teeth with ridges; eyes very large, oval-shaped, emerald green in life; first dorsal fin broadly triangular, with rear tip extending behind pelvic fin midbases; lateral trunk denticles imbricated; colouration in life brownish gray laterally, becoming lighter ventrally; fin margins lighter along posterior edges; dorsal rostrum surface with two distinct longitudinal dark stripes; lateral rostral teeth dark-edged (Ref. 87357).
Description: Body slender, snout flattened, forming very elongated, blade-like rostrum, pre-barbel length 16.6-17.5% of total length (Ref. 87357). Head very narrow, subtriangular, strongly depressed over eyes, height greatest at gill opening, head width at mouth 6.2-7.9% of total length; head width at nostril 4.1-5.0 times in preorbital length (Ref. 87357). Trunk narrow, tapering toward caudal origin; subcircular in cross-section; pectoral-pelvic space 12.9-15.0% of total length (Ref. 87357). Head length 0.5 times trunk length; pectoral-pelvic length short, 12.9-15.0 of total length; dorsal-caudal space 7.8-9.2% of total length; caudal peduncle height 3.4-4.1 into dorsal caudal space, and width 0.8-1.0 in height; lateral keels present; no precaudal pits (Ref. 87357). Rostrum is very long, narrow, and tapering; pre-oral length 27.7-29.6% of total length; sides of rostrum slightly convex from tip to barbels and nearly straight between barbels and nostrils; ratio of pre-orbital length to rostrum width at nostrils 4.1-5.0; two parallel rows of 4-5 enlarged pits present on underside of pre-barbel snout; barbels closer to mouth than rostral tip, pre-barbel length 58.4-60.7% of pre-oral length; space from barbel to nostril 0.7-0.9 times space from nostril to first gill opening; barbels ending 0.2-0.5 eye length anterior to nostrils in adults, posterior to them by 0.3-0.7 of eye length in juveniles; large lateral rostral saw-teeth along sides of snout and head total 21-32, including 15-22 teeth in front of barbels and 6-10 teeth behind barbels; post-narial lateral rostral teeth extending 0.1-0.5 times eye length behind eye; adults have up to 4 smaller rostral teeth between large lateral rostral saw-teeth; juveniles with 1-3; prominent longitudinal ridges on bases of lateral and ventral rostral teeth; ventral rostral teeth anterior to barbels number 13-18, between barbels and nostril 5-7; a ventral rostral tooth in front of nostril but this not enlarged (Ref. 87357). Eyes oval, very large, lateral on head, length 3.5-4.6% of total length; distance to last rostral tooth 0.3-1.9; inter-orbital concave width 4.2-5.0% of total length; sub-ocular groove present; spiracles small, length 2.3-5.4 times eye length, crescent-shaped, slightly oblique; located just posterior to eye; gill openings small, lateral on head, closer to ventral surface than dorsal; each similar in length, evenly spaced except for fourth and fifth openings slightly closer to each other; fifth gill opening arches slightly around pectoral fin origin (Ref. 87357). Nostrils small, anterior nasal flap lobe-like and well-developed; excurrent apertures transversely oval, nearly circular, width 0.7-1.0% of total length, 3.2-4.0 in internarial width; distance from nostrils to mouth 1.1-1.3 times internarial space; distance from nostrils to barbels 1.1-1.4 times distance between nostrils and mouth corners (Ref. 87357). Mouth broadly arched, extending forward to below posterior third or fourth of eye, width 4.0-4.3% of total length; labial furrows short, upper and lower about equal in length; teeth with a single prominent acute cusp, in well defined rows, bases flattened and rounded; tooth row counts 31-36 on upper jaw and 29-34 on lower jaw; series of functional teeth about 3-4 (Ref. 87357). Lateral trunk dermal denticles closely imbricated, with flat mostly tricuspidate crowns; outer margins of dorsal and pectoral fins are densely covered with fine denticles in subadults and adults (Ref. 87357). Pectoral fins large, anterior margin weakly convex, anterior margin length 8.9-10.4% of total length, 32-38% of pre-oral length; posterior margin weakly concave, apex broadly rounded; inner margin nearly straight; height about equal to posterior margin length; free rear tip terminates anterior to origin of first dorsal fin; pectoral fin skeletal radials divided into 2-3 segments; propterygium with one radial, mesopterygium with 7 radials, metapterygium with 13 radials, and total radial count 21; pelvic fins large, anterior margin 5.0-6.2% of total length, length 1.4 times into first dorsal fin length, 1.2 times in second dorsal fin length; anterior margin slightly convex, posterior margin nearly straight, broadly rounded at apex; inner margin nearly straight, length about equal to posterior margin length, free rear tip narrowly acute (Ref. 87357). First dorsal fin broad, triangular, anterior margin slightly convex, with broadly rounded apex anterior to insertion, posterior margin slanting posteroventrally; inner margin straight, free rear tip narrowly acute; origin about opposite pectoral free rear tips or in front of them by 0.5 times eye length or less; insertion over pelvic fin origins or slightly anterior to them by less than 0.25 times fin base, free rear tip extending far posterior and about opposite or slightly in front or behind pelvic fin insertions and behind pelvic midbases; second dorsal fin subequal to first, with base shorter but height as great or greater; origin behind pelvic insertions by distance about 0.4-1.0 times first dorsal base; caudal fin long, dorsal margin slightly convex, length 18.6-20.0% of total length, lower post-ventral lobe absent, upper post-ventral margin broadly rounded; terminal lobe well developed, caudal terminal margin slightly concave, apices angular (Ref. 87357). Total vertebral count 132-139; monospondylous precaudal count 42-45; precaudal count 90-93; intestinal valve turns 6-7 (Ref. 87357).
Colouration: In life, large, oval-shaped eyes emerald green; lateral trunk brownish gray dorsally, slightly darker above, becoming lighter below lateral line; ventral surface whitish with some darker mottling; dorsal, pectoral, and pelvic fins with light to white posterior fin edges; caudal fin terminal margin and upper post ventral margins white; anterior margin and apex of dorsal fins and dorsal caudal margin darker, more conspicuous in juveniles than adults; two distinct dark longitudinal stripes extend length of lighter coloured dorsal rostral surface; lateral rostral teeth dark-edged, ventral rostral teeth dark and conspicuous against light underside of snout (Ref. 87357). After preservation, these sharks are a uniform medium brown above, white below (Ref. 87357). |
