Really, there is no way to know for sure. Now that you say how green he is, I'm starting to think that he may be some sort of hybrid. And the fact that a pet store sold him to you suggests also that it could be a hybrid. But there is no way to know for sure. I'd have to see some more pics of him before I could make my judgement though.
On the upside though, I bet you got a good deal on him at the pet store. Pet stores don't know crap when it comes to amphibians. I went to petco to buy a baby whites treefrog, and they wrote the slip up for a green frog (which cost about 1/4 the price!) So I bought 4 more.
But back to the subject... I'm not completely sure. If you find the cord, I'd be interested in seeing the other pictures, sounds like an interesting little specimen.
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1.1.0 Sunburst Veileds (Oscar and Lizzie)
1.1.0 Azureus darts
2.3.0 Mantids
1.0.0 Albino Pacman (Grumpy)
2.0.0 White's Tree Frogs
0.2.0 Cats (Oreo and Doodle)