Author: Bleeker, 1854
Field Marks:
A moderate-sized, white-spotted Mustelus with relatively narrow internarial space, buccopharyngeal denticles covering almost entire oral cavity, unfringed dorsal fins, relatively small pectoral and pelvic fins, and 71 to 91 precaudal centra. It is the only white-spotted smooth- hound in the Indian Ocean and western North Pacific.
Diagnostic Features:
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 7.5% of total length, preorbital snout 6 to 7.8% of total length; internarial space fairly narrow, 2 to 2.9% of total length; eyes large, eye length 1.7 to 2.5 times in preorbital snout and 2.4 to 4.1% of total length; interorbital space narrow, 3.7 to 4.5% of total length; mouth fairly short, about equal to eye length and 2.5 to 3.7% of total length; upper labial furrows considerably longer than lowers and 1.9 to 2.5% of total length; teeth molariform and asymmetric, with cusp reduced to a low point; buccopharyngeal denticles covering almost entire palate and floor of mouth. Interdorsal space 19 to 23% of total length; trailing edges of dorsal fins denticulate, without bare ceratotrichia; first dorsal broadly triangular, with posteroventrally sloping posterior margin, its midbase closer to pelvic bases than to pectorals; pectoral fins moderate-sized, length of anterior margins 11 to 15% of total length, width of posterior margins 7.5 to 14% of total length; pelvic fins moderate-sized, anterior margin length 5.4 to 8.2% of total length; anal height 2.2 to 3.4% of total length; anal caudal space greater than second dorsal height, and 6.5 to 9% of total length; ventral caudal lobe not falcate in adults. Crowns of lateral trunk denticles lanceolate, with longitudinal ridges extending their entire length. Skeleton not hypercalcified in adults; palatoquadrates not subdivided; monospondylous precaudal centra 33 to 41, diplospondylous precaudal centra 35 to 54, precaudal centra 71 to 91. Colour uniform grey or grey-brown, above, light below, usually with numerous white spots but no dark spots or dark bars. Development ovoviviparous. Size moderate, adults 55 to 117 cm.
Geographical Distribution:
Western North Pacific: Southern Siberia, Japan, the Koreas, China, including Taiwan Island, Viet Nam. Western Indian Ocean: Kenya (P.C. Heemstra, pers. comm.).
Habitat and Biology:
An abundant, wide-ranging temperate and tropical bottomdwelling shark of continental waters, in the intertidal and subtidal regions, commonly close inshore, especially on mud and sand bottoms.
Ovoviviparous, without a yolk-sac placenta; number of young 1 to 22, mostly 2 to 6, average about 5, increasing markedly with size of mother. Gestation period about 10 months, with young born in spring. Adults mate in summer (June and July). Apparently fairly fastgrowing (based on growth curves, length-frequency data and growth rings and size increase of vertebrae) with maturity occurring between three and four years after birth (Taniuchi, Kuroda and Nose, 1983).
Eats mostly bottom invertebrates, with crustacea in about 85% of 412 individuals examined by Taniuchi, Kuroda and Nose (1983), fish 23%, polichaetes 18%, and sipunculoid worms 13%. Crustacean prey primarily brachuran crabs, including cancrids and portunids, but also anomuran crabs, ghost shrimp, true shrimp, and manis shrimp; fish include jacks, herring, filefish, morids and mackeral; eggs (of fish?) and bivalve molluscs are also eaten.
Size:
Maximum about 117 cm; males maturing at about 62 to 70 cm and reaching about 96 cm, females maturing between 62 and 70 cm, and reaching 117 cm; size at birth about 30 cm.
Interest to Fisheries:
An important species off Japan, fished with longlines and probably other gear; meat utilized for human consumption. Also fished off China, including Taiwan Island and the Koreas, and probably elsewhere where it occurs.
Remarks:
Until recently Red Sea, Indian Ocean and western North Pacific smooth-hounds were mostly referred to this species (cf. Fowler, 1941), but Dr P.C. Heemstra (1973 and pers. comm.) found that most valid records of the species were from the western North Pacific, from Japan, the Koreas and the Soviet Union to VietNam; an exception is material collected off Kenya, to be reported by Dr Heemstra. Red Sea and Indo-PakistaniSri-Lankan Mustelus are referable to M. mosis
Mustelus manazo is very close to other white-spotted Eastern Hemisphere smooth-hounds (all of which are allopatric to M. manazo), but differs from them in its smaller size. It additionally differs from M. asterias in having fewer vertebrae, from M. palumbes in having smaller fins, and from M. antarcticus and M. Ienticulatus in having a narrower internarial, more extensive buccopharyngeal denticles, and less falcate caudal fin.
Type material:
Syntypes: Rijksmuseum van Natuurlijke Historie, RMNH 7396, 350 to 460 mm. Type Locality: Nagasaki Market, Japan.