LONGNOSE SAWTAIL CATSHARK
A shark with a long snout and a crest of saw-like dermal denticles
The Longnose Sawtail catshark (Galeus longirostris) is a little-known species of catshark, belonging to the family Scyliorhinidae. They can be found off the northwestern Pacific islands of Amami Ōshima, Ogasawara, and Izu at depths of 1,148-1,804 feet. They can reach a length of 2.6 feet. It is characterized by a long-flattened snout, a long space between the pelvic and anal fins, and a crest of enlarged dermal denticles along the dorsal caudal fin edge. Adults are plain dark gray above, while juveniles have a few faint dark saddles on the back and tail. There is not enough data to evaluate this shark.
Family: Scyliorhinidae – Catsharks
Common Name– Ground Sharks
Common Name– Catsharks
Status: IUCN Red List DATA DEFICIENT
Average Size and Length: Mature males have been measured at between 66-71 cm/2.2-2.3 feet. Mature females have been measured at 68-78 cm/2.2-2.6 feet. The maximum recorded has been 80 cm/2.6 feet.
Current Rare Mythical Sightings: The first known specimen of the Longnose Sawtail catshark was hooked on a bottom longline off the Ogasawara Islands in 1983. The new species was described by Hiroyuki Tachikawa and Toru Taniuchi in a 1987 issue of the Japanese Journal of Ichthyology, and given the specific epithet longirostris from the Latin longus (“long”), and rostrum (“snout”). A 68 cm long female caught off Amami Ōshima was designated as the type specimen. Within the genus, this species most closely resembles the Broadfin Sawtail catshark (G. nipponensis).
Teeth and Jaw: The mouth lining is greyish white. The mouth forms a wide arch and has well-developed furrows around the corners. The tooth rows number 60–70 in either jaw. Each tooth is small, with a narrow central cusp and 3–6 smaller lateral cusplets.
Head: The head is flattened. The snout is long and broadly rounded. The nostrils are large and divided by triangular skin flaps on their anterior rims. The large, horizontally oval eyes are equipped with nictitating membranes and have thin ridges underneath. There is a medium-sized spiracle behind each eye.
Denticles: There is a distinct crest of enlarged dermal denticles along the upper margin of the tail. The dermal denticles are small and overlapping, each with a median ridge and three marginal teeth.
Tail: The caudal peduncle is compressed from side to side, and leads to a low caudal fin with a small lower lobe and a ventral notch near the tip of the upper lobe. The tail is elongated.
Demographic, Distribution, Habitat, Environment and Range: The Longnose Sawtail catshark can be found in the northwest Pacific around the southern islands in Japan. They can be found on or near the bottom on the upper insular slopes between 1,148-1,804 feet. They are considered bathydemersal.
Aesthetic Identification: The Longnose Sawtail catshark is uniform grey dorsally in adults. There are a few obscure dusky saddle blotches at the dorsal fins and on the caudal fin in young. They are whiteish ventrally. The dorsal and pectoral fins are white-edged. The dorsal and caudal fins are without black tips. The body is stout. The five pairs of gill slits are short, with the fifth pair over the pectoral fin bases. The origins of the first and second dorsal fins lie over the latter half of the pelvic fins and the midpoint of the anal fin. The dorsal fins are roughly triangular with blunt apexes, with the first slightly larger than the second. The large, wide pectoral fins have rounded corners. The pelvic fins are of moderate size. The claspers of mature males are extremely long, reaching past the origin of the anal fin, and have patches of hooks on the underside. The base of the anal fin measures around 11–13% of the total length, about equal to the distance between it and the pelvic fins.
Biology and Reproduction: Unknown. No adult females have been recorded with egg cases or young.
Behavioral Traits, Sensing and Intelligence: Unknown.
Longnose Sawtail Catshark Future and Conservation: There is not enough data to evaluate, however they have been reported as common among their range. They are likely taken as bycatch by deepwater trawlers.
Longnose Sawtail Catshark Recorded Attacks on Humans: Not a threat to humans.