I"m not sure what the color spectrum of your lighting is, but the purple Antennal Scales and maxillipeds are unlike anything I've seen on your standard Gonodactylus chiragra. Still, if the animal comes from the Indo-Pacific, there aren't many other possibilities unless it is a new species. The red pleopods in the 4 th image are closer to what I would expect in a G. c female. To your eye in daylight, do the scales really look this purple?
The largest G. chiragra that I have ever collected was 95 mm and the largest reported in the literature (that I can find) is 104 mm - just a hair over 4 inches.
Roy