I just got a nice sized order of Periplaneta americana in today and I noticed a few of them are quite dark. Does anyone know a better way than color variation to tell the difference between Periplaneta americana, fuliginosa, and brunnea? It would be great if a few P. brunnea or fuliginosa snuck their way into this shipment because they are much harder to find. Any help would be appreciated but either way, yay new roaches! 
The group:
A comparison of the two side by side, one certainly P.americana, the other...??? (sorry for this poor shot, the plastic wasn't clear)
Another shot of one of the oddballs:
Last one:
The group:
A comparison of the two side by side, one certainly P.americana, the other...??? (sorry for this poor shot, the plastic wasn't clear)
Another shot of one of the oddballs:
Last one: