Just my opinion, so take it with a grain of salt: I always felt unsure looking at pictures like this for sexing. It used to seem like many people had a good eye for it but I was never very confident either way. However on this one, I thought it looked like an obvious female with very dramatic tapering just past the vent and a short tail. I would vote a resounding female, but it seems like there's a lot of disagreement over this one with many people voting male. If you find out for sure what it is, be sure to let us know.