Diagnosis |
This medium-sized species (to at least 62 cm DW) is distinguished by the following set of characters: disc weakly rhomboidal; preorbital snout moderately elongate with weak apical lobe, snout angle 113-119°; rounded pectoral-fin apices, angle 96-98°; small, protrusible orbits; relatively broad mouth, its width 0.9-1.2 in internasal width; distance between first gill slits 2.5-2.6 times internasal distance; distance between fifth gill slits times 1.5-1.7 times internasal distance, 27-29% of ventral head length; broad pelvic-fin base, 13-17% DW; in juveniles, the tail behind sting is subcircular with deep longitudinal ventral groove and prominent mid-lateral ridge, in adults, it is weakly depressed; 1-2 (usually 1) small, broadly heart-shaped to seed shaped suprascapular denticles, primary denticle band and thorns absent; secondary denticle band irregularly sub-oval, relatively narrow (its maximum width across scapulocoracoid barely exceeding its width at spiracles), with well-defined lateral margins, narrowly tapering near tail base; fully developed band and covering entire dorsal surface of tail by 33 cm DW; dorsal surface mainly uniformly coloured (occasionally with dark flecks in specimens smaller than 25 cm DW), disc margin sometimes paler dorsally; ventral disc uniformly whitish, not black edged; in adults, darker dorsal surface of tail sharply demarcated from paler ventral surface; in neonates and juveniles, dark tail with conspicuous white saddles, its distal portion usually almost uniformly dark; pectoral-fin radials 124-129; 108-111 total vertebral count (excluding 1st synarcual centra), 43-44 monospondylous centra, 65-68 pre-sting diplospondylous centra (Ref. 90168). |