I'm gonna say female. I can kind of see the "lip" shaped lighter color slit in between the book lungs. Also, the angle is not horizontal which would mean make. I'm going to say female, but I'm no expert at ventral sexing. I've just done a bunch of research and been comparing pictures to try to practice.
@MikeC I would have to imagine so because out of all the species they carry, this is one of like 3 or so that they were selling as sexed females. (i don't think they often go ventrally but I'm purely speculating) the first time it molts I'll be able to tell for sure but in the meantime I was just checking