I've seen a bunch of really nice Harlequin pictures in the Photography forum at RC, especially by gregr. Yours seems to lack the large claws that really make them the efficient predators of starfish they are, unless it's still a baby and they grow out later. Even with that, the resemblance is passing, do you think?
Here's a slideshow of MtnDewMan's harlequins:
http://reefkeeping.com/issues/2002-07/reefslides/