3-4 inches is middle ground. Some of my frogs didn't croak for quite a long while after they were "mature". Black marks do not matter really, but the beard does. During breeding season, males' throats turn dark almost like a "beard." The frog should croak at this time too. But at this stage, it is hard to say. Sometimes the frog has to be properly triggered to begin calling, so who is to say if it has or has not been triggered correctly. I would go with a nice clean answer of "I really couldn't even begin to guess." Haha...Good luck to you.
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Andy Maddox
AIM: SurfAndSkimTx04
MSN: Poloboy32486@hotmail.com
Yahoo:surfandskimtx04
Houston Herp Key
The Reptizone