I just saw now that Xanthosoma maximilianii is also stated as growing in dry tropical forest according to the monocot site!
That makes no sense!
I do wonder if Xanthosoma taioba is the now accepted name for Xanthosopa saggitifolium which would become synonym. Whatever I search on the web with X.taibo I get X.sagitifolium instead!
And strangely enough the Flora do Brasil does not list X.sagitifolium any longer and I'm am very sure it was listed some months ago where I searched last, the list was also longer then! They also have renewed their site!