Regarding whether or not how to tell that it's actually a dwarf or not.

There aren't any actually dwarf retics. There are super dwarves and localities that grow smaller than the mainland retics. I believe, but may be wrong, that mainland retics are from the Sulawesi Island. Whereas some known "dwarf" retics are from Madu Island, Jampea Island, and Kayudi(not sure on spelling). Retics are strong swimmers and can can travel great distances at sea. This has lead them to inhabiting smaller islands with less resources for their huge sizes. At one point I saw a chart showing how different retics had slightly different head shapes. I think that was on a different forum though.

I hope this helped and that too much of what I said wasn't wrong.