So, there seems to be some knowledge on this guy already, but here's a quick overview! Commonly known as the Diamondback squid, it is fairly large (about 100 cm Mantle length). The large muscualr fins (which seem to be the same length as the mantle) will help you ID it. It seems to have a wide distribution, and is commercailly fished.
Thysanoteuthis rhombus
Info at: Thysanoteuthis rhombus
Thysanoteuthis rhombus
Info at: Thysanoteuthis rhombus