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Author: Günther, 1870

Field Marks:
Five pairs of lateral gill slits, long, narrow sawshark snout 26 to 29% of total length, largely lanceolate denticles, two spineless dorsal fins, and no anal fin.

Diagnostic Features:
Rostrum long, narrow, and narrowly tapering, length of preoral snout 26 to 29% of total length. Bases of rostral barbels about 1.1 to 1.2 times closer to mouth than rostral tip; distance from rostral barbels to nostrils about equal to distance from nostrils to first to fourth gill slits. About 15 to 26 large rostral teeth on each side of rostrum in front of rostral barbels, 9 to 17+ behind them. Distance from mouth to nostrils 1.1 to 1.2 times internarial space. Tooth rows 34 to 58 in upper jaw. Dorsal and pectoral fins covered with denticles inlarge specimens. Lateral trunk denticles largely unicuspidate. First dorsal origin behind free rear tips of pectorals by eye length or more.

Geographical Distribution:
Western North Pacific: Japan, the Koreas, northern China, Taiwan Island, possibly the Philippines.

Habitat and Biology:
A common sawshark of the western North Pacific continental shelves and upper slopes on or near bottom. Lives in coastal waters, on sand or mud bottoms. Ovoviviparous, number of young usually 12. Feeds on small bottom organisms; said to use barbels along bottom and poke the bottom with its snout.

Size:
Maximum total length for adult females about 136 cm.

Interest to Fisheries:
Probably of limited importance, though in Japan its meat is considered of high quality and used to prepare "kameboko" for human consumption.

Remarks:
This species is very close to P. cirratus and was referred to that species by earlier writers. Günther (1870) distinguished the two species by differences in tooth counts, and by comparison of the distance between rostral barbels and nostrils (equal to distance between nostrils and fourth gill slits in cirratus, nearly equal to that between nostrils and first gill slits in japonicus). However, the proportional character fails in that some japonicus examined have the barbel-nostril interspace equal to that from the nostrils to fourth gill slits, and tooth counts overlap in the material examined and in literature counts. Use of tooth counts is also confounded by increases in tooth counts with growth in this and probably other sawsharks (a small Japanese sawshark 49.5 cm total length had 34 rows of upper teeth, a large one about 136 cm 57 rows, while intermediate-sized specimens had intermediate counts). Because of the limited material examined of P. cirratus, I am uncertain if rostral tooth counts and the position of the barbels on the snout (closer to the snout tip than mouth in cirratus, slightly closer to the mouth than the snout tip in japonicus) are valid differences between these species. The separation of the two species P. cirratus and P. japonicus is unsatisfactory at present, but I hesitate to merge them until more adequate samples than I have been able to examined can be compared.

Sawsharks from the Philippines may be this species or P. cirratus (see that species for a discussion).

Type material:
Syntype: British Museum (Natural History), BMNH 1862.11.1.37. Type Locality: Japan.

Japanese sawshark (Pristiophorus japonicus)