Just call him an EE (easter egger) don't call him Ameraucana.. since he has things that don't match any of the breed standard- yellow legs.. calling him that can get a whole bunch of folks coming down to give lectures, lol.. It's a very long lasting, widespread problem of the Araucana, Ameraucana and EE getting lumped together. (some get irritated at misspelling Ameraucana.. I;m not sure if that's the right spelling.. often I just play it REAL safe and shorten it to Amer... lol)
He could either be an EE with this kind of white, called dominant white.. OR he could really be an Leghorn- Amer or EE cross/mix. He matches both descriptions easily. If there are no white Amer/EE in their flock, the only whites being Leghorns, then it's very likely to be Leghorn cross/mix.
In any case.. calling him an EE will be completely safe for you to do so..
He could either be an EE with this kind of white, called dominant white.. OR he could really be an Leghorn- Amer or EE cross/mix. He matches both descriptions easily. If there are no white Amer/EE in their flock, the only whites being Leghorns, then it's very likely to be Leghorn cross/mix.
In any case.. calling him an EE will be completely safe for you to do so..