Anterior margin of disc with double curvature; mouth subterminal; spiracles very small, subcircular and ventral to the plane of the pectoral fins; denticles very sparse on body surface; tail whip-like and long, can be as long as DW in adults when intact; caudal spine absent. Body colour bluish black with purplish hues above; blackish margin along anterior disc becoming broad and very distinctive at level of concavity; dorsal fin with a distinct white tip (becoming faint in adults); ventral surface mostly white.