D onilahensis has a lot more powder on the trunk, less stems, more spaces between the leaflets, thicker leaves, is a larger tree overall, and has different flowers (the ultimate difference). Otherwise they do look superficially the same... this tree was one of many bizzarre variations from D lutescens parents, and possibly there is some D onilahensis in the gene pool... they are redoing the Dypsis again soon, and D onilahensis may end up being lumped in with a lot of other popular species, too... like D baronii for example... and possible even D lutescens (guess even floral differences can be variable and require one to include very different individuals in the same species).