Author: Pietschmann, 1908
An unspotted, moderate-sized Mustelus with a short head and snout, broad internarial space, fairly small eyes, narrow interorbital, upper labial furrows equal to or slightly shorter than lowers, low-crowned teeth with weak cusps, buccopharyngeal denticles covering anterior half of buccal cavity, lateral trunk denticles usually lanceolate and with complete ridges, unfringed dorsal fins, 73 to 80 precaudal centra, and a semifalcate ventral caudal lobe. It is the only smooth-hound with the above characters where it occurs.
Body fairly slender. Head short, prepectoral length 17 to 21% of total length; snout moderately long and bluntly angular in lateral view, preoral snout 5.7 to 7.1% of total length, preorbital snout 6.2 to 7.7% of total length; internarial space broad, 2.4 to 3.2% of total length, eyes fairly small, eye length 2.3 to 3.1 times in preorbital snout and 2.1 to 3.5% of total length: interorbital space narrow 3.6 to 4.5% of total length; mouth fairly long, somewhat greater than eye length and 2.5 to 3.7% of total length; upper labial furrows equal or slightly shorter than lowers and 0.8 to 1.4% of total length; teeth molariform and asymmetric, with cusp reduced to a low point, cusplets absent except in very young sharks; buccopharyngeal denticles covering anterior half of palate and mouth floor. Interdorsal space 18 to 22% of total length; trailing edges of dorsal fins denticulate, without bare ceratotrichia; first dorsal somewhat falcate, with posterior margin abruptly vertical from apex, its midbase about equidistant between pectoral and pelvic bases; pectoral fins moderate-sized, length of anterior margins 12 to 14% of total length, width of posterior margin 8.3 to 11% of total length; pelvic fins moderately large, anterior margin length 6.8 to 8.4% of total length; anal height 2.7 to 3.4% of total length; anal caudal space greater than second dorsal height, 6.1 to 8.1% of total length; ventral caudal lobe more or less falcate in adults. Crowns of lateral trunk denticles lanceolate or weakly tricuspidate, with longitudinal ridges extending their entire length. Skeleton not hypercalcified in adults, except for slight expansion of scapulocoracoid tips; palatine processes of palatoquadrates subdivideo at symphysis, with a short separate medial segment on each side; monospondylous precaudal centra 29 to 35, diplospondylous precaudal centra 40 to 48, precaudal centra 73 to 80. Colour uniform grey or grey-brown, above, light below, no white or dark spots or dark bars. Development viviparous. Size moderate, adults 65 to 101 cm.
Western North Pacific: Japan, the Koreas, China, (including Taiwan Island), Viet Nam.
Habitat and Biology:
A common western Pacific temperate and tropical inshore bottom-dwelling shark, found down to at least 51 m depth.
Viviparous, with a yolk-sac placenta; number of young 5 to 16 per litter, with larger adults having larger litters of young. In Japanese waters the gestation period is 10 months, with fertilization occurring in July and birth occurring in April and May.
Probably eats bottom-dwelling invertebrates. especially crustaceans.
Maximum at least 101 cm, adult males maturing between 62 and 71 cm and reaching at least 87 cm, females maturing at about 80 cm and reaching about 101 cm; size at birth about 28 cm.
Interest to Fisheries:
Regularly fished off Japan, China and Taiwan Island (Province of China).
The name Mustelus kanekonis is often used for this species, but Heemstra (1973) determined that it is a synonym of M. griseus. In its western North Pacific range the only other smooth-hound is M. manazo, an ovoviviparous, white-spotted, smaller species with longer upper labial furrows and other differences.
Holotype: Specimen of 633 mm formerly in Naturhistorisches Museum, Vienna, apparently lost (Heemstra, 1973). Type Locality: Japan.