What is this legspan??? If it is at the 4.5'' or close to that mark then it's 100% obvious female. Males have a blackish smoldering color mark that is very obvious for male. Males at the 4.5'' mark would be mostly pen-ultimate for A. seemanni, which is the time where all male T.'s are the easiest to ventral sex since they are one molt away from maturity. If this specimen is a male I would be too surprised, because I've seen so many females and males at this size to easily tell them apart. As someone who bred this species before, I believe this one to be female, and if I'm wrong I'll but this male at maturity for a future breeding with my female if it's in the US.
@Snakes Female, if it's past 5'' then it's certainly female
@spodermin@Drea Time for an education on A. seemanni sexing for you new folks in the hobby. A. seemanni are very easy to vent sex if you know what your looking at. For starters, if you look inbetween the book lungs, you probably noticed the furrow like @spodermin spotted out. But what fools people is that females can also have this "dark furrow". What you really need to look at for A. seemanni is not just the "furrow" because you'll be missing a piece to the puzzle. What other factors you need to look at is the booklungs, male A. seemanni have close-in book lungs as they get older and reach close to maturity. There are more factors, but we'll settle on this case. Here's a link to confirmed females if you still wanna argue.
@Snakes since it's 5'' it would be a pen-ultimate male, therefor "his" supposed booklungs will be close together and not distant from each other. But it's not as you see in this photo. (Conclusion Music Intensifies) Female
@spodermin I'll be waiting for that molt to verify, then the $5 sent on paypal to me