I hope yours drops a nice load of venom squirtin' babies...but I had one that looked just like that for years that never did. It was huge when I got it, I'm still not sure if she was just really heavily fed before I got her, or if she was gravid and I just failed to create the correct conditions for her. I also wonder if attaining big bulk is just natuaral for this species, as many wild caughts I've seen look like that.
Is it possible she managed to dump some abortive embryos without you noticing? With most WC species you can assume that most females are gravid due to the long gestation period. Thus, I would be more prone to theorize that A.bicolor is prone to aborting than somehow naturaly achieving and maintaining that degree of distension.
It's certainly plausible, but she was in a fairly small terrarium without much in the way of decoration, so it would have been hard to hide. Plus, she never got any smaller in the time I had her. I had her for about three years before she died, so I suppose it's possible that she perished as a result of not being able to give birth. Of course, as a wild caught, there's know way to know how old she was. My impression (based on various forums and message boards) is that buthids in general are not especially long lived.
My feeling is that she was not gravid, but mearly fat. Hmmm...post mortem disection would have answered some of these question, perhaps...too late now
Maybe she was parasitized? There are certainly vertebrate parasites that cause distension -- I wonder if there is an invert equivelent. Or maybe she was just fat, which brings up other questions as to their metabolic rates in times of plenty. What temperature did you have her at? As for the death, most Buthids aren't that long lived, that's for sure. P.transvaalicus is among the more long-lived from my understanding, but if you got her as a mature specimen then three years isn't that bad at all. She may well have been five years or more.
The temperature may have been an issue, as I have only recently began to give my scorpions supplemental heat (see my response to Kenny in annother post). However, since I don't have AC, during the summer months, the room temps were quite high, often in the 90's and rarely dropping below 85f. Even in the winter, temps rarely drop below 72f, and on the higher shelves it's closer to 80. I also tend to feed my desert scorps rather sparingly, maybe one or two crickets a week at most, so I don't think I was overdoing that aspect.
The parasite idea is interesting. On a side note, I once had a talk with a biologist who also had connections with the hobby (I say this just to indicate that this wasn't just hobbyist lore) who told me that imported centipedes were usually infested with various protozoans that tended to stunt their growth. He found that if he injected a feeder cricket with Flagl prior to feeding it to a centipedes, he could effectively kill off the parasites. He claimed that centipedes so treated went on to grow to much bigger sizes than their untreated bretheren.
I wonder if this type of treatment would be effective on other invertebrates. Not necasarily to make them grow larger (as scorpions stop molting at adulthood anyway), but as a treatment when we have cause to suspect parasitism.