Very nice Andy.
I see two very very nice examples there.Im not sure of the exact locality of this type of Marble but i reckon ive seen enough of them to have established that this is a smaller ray than my AAA Marbles and the earlier Marbles that were imported for instance.I've got a pair myself and the males fully mature and hasn't grown a cm in the past 18 months(he's 11" disc).We imported some 11" females a couple of years ago,these were already gravid and one gave birth to 4 fully developed pups that were tiny compared to my MM pups which are born with a 14cm disc,these pups were half that size.
I don't have scientific proof of any of this its just an observation.
How big is your gravid female? i guess no bigger than 14-15" disc?...oh and how big is dad also.
Good luck with the birth.