Actually, Alocasia amazonica is not listed in ITIS, ThePlantList.org, TROPICOS, WCPR.
Alocasia x amazonica is listed as an invalid synonym of Alocasia x mortfontanensis André, Rev. Hort. 63: 174 (1891) which itself is under review and an unplaced name.
The originial publication details list it as an "artificial hybrid or cultivar" of A. longiloba × A. sanderiana.
Your reference to Exotic Rainforest clearly states "Alocasia Amazonica
This plant is a hybrid and not a species.
The name is not scientific but is instead a horticultural common name"
http://www.exoticrainforest.co...
I think your best bet is to list it simply as
Alocasia hybrid 'Poly'; Then as Sue suggests. list all the common names such as A. x amazonica and A. amazonica, as well as the cultivar "Polly" - since it's being sold under all those names. Then move any photos or details from the incorrect entries and delete the plant listings for A amazonica and A. x amazonica since they don't exist botanically.
You may want to comment on this mess!
