Like you I have assumed it to be a male for a long time but since for the last couple of days he is digging places and rubbing himself to rock surfaces and biting them, I thought he might be a female. But he is very agressive like a male.
Here is a male that I have that looks quite a bit like yours. You can never be sure with jags though....I can't tell you how many "males" I have seen just up and start laying eggs....lmao!