Permalink : http://hdl.handle.net/2115/86614

JaLCDOI : 10.14943/bull.fish.72.1.9

KEYWORDS : Body color;Placoid scales;Alar thorn patch;Clasper;Maturity;T/S Oshoro-maru;T/S Hokusei-maru

The softnose skate, Bathyraja diplotaenia (Ishiyama, 1952) (Rajiformes : Arhynchobatidae), was morphologically examined and described on the basis of 48 male (179.4-856 mm total length) and 45 female specimens (172.8-849 mm total length) to describe intraspecific variation with growth and distribution of placoid scales, alar thorn patch, and body color of the species. The results make clear that placoid scales on the dorsal side of the disc mostly disappear in specimens of 439.3-473.2 mm total length, the alar thorn patch appears in male specimens of 665-751 mm total length, and the body color changes in specimens of 363.6-653 mm total length. In addition, it reveals that the species starts to mature at about 500 mm total length and matures at about 750 mm total length based on growth of clasper length and presence of the alar thorn patch.