Wow Roy i think you've almost hit it on the head with that one. Google results for Lysiosquilla tredecimdentata are images of a mantis very similar to mine, orange eye stalks, band on the telson, anntenal scales are almost the same, and the antennas are almost exactly.
The only thing that is not right with this is the raptorial appendage - there are no tiger/zebra mantis markings at all, they are a pale blue to white colour and they have 8 spines - is it quite usual for something that 'normally' has 9 or 10 spines to have 8? Or could this simply be a different locale? Also roy do females usually have dactyl spines? My understanding is that males do the hunting and female tend the eggs (and the small shrimp that live in the burrow?) so the males would have spines. Of course this is only going of the L. maculata pair image on your site. This i find weird. it is definatly female i even took the animal out of the water to see if it was hiding its gonopods and it definatly has none.
Roy - there IS a red spine on the uropod, well more purple actually, and it was still left in the shed. i will take a photo of this. [done and will post]
This is definatly the closest to IDing the animal we have come but i still dont think the raptorial appendage colouration fits but like i said could this not just be locale? Have you got any of these in the labs roy?
One other thing - the L. tredecimdentata has speckled eyes, whereas this animal does not.
here are the images, one with flash one without, this moult is about 5 days old so please forgive the "freshness".
Thanks for your continuing help with this ID.
Thanks
James