wow... tough call. may be the one nearest to the right on the 1st pic, but if it is a male, that is a really nice male. you must have some very high grade red's and while that is an enviable bonus, it makes for the sexing harder.
I would not worry too much however about identifying the males vs. the females. If you have 10+ or more shrimp, mathematically there has to be 1-2 males at least among them and you really only need 1 male to start having your colony grow. As soon as you see berried females (3-4 weeks time unless they came pregnant) you will know there is at least one male among the bunch
best of luck and enjoy your shrimp! they look fantastic!