What I meant is, if you caught it yourself, then you would know where you caught it and you could use a field guide to figure what species you have. Example - if I caught a gray treefrog in my back yard, I would know it was H. versicolor, because that is the only species of gray treefrog here in New England.
If its male and you happen to hear it call, then maybe you could identify it, providing you know what one or the other sounds like. I do believe I search of the internet can provide some help here. If not there are CD's for sale.
Of course if you bought in a store and the frog never sings, well then its a big mystery.