Following recent paper published in Taxon "Fixing stray traditions in gingers: The identity and nomenclatural history of Zingiber neesanum and other entwined names (wiley.com)
" dealing with and resolving century old confusion of the names Z.neesanum (J.Graham) Ramamoorthy and Z.macrostachyum Dalzell. which had a long ambiguous history with incorrect application of name Z. neesanum for white flowered Zingiber found widely in Central and Southernmost Western Ghats. The lack of fieldwork in type locality and historical confusion also lead to publication of a new name Z. diwakarianum R.Kr.Singh, now to be treated as a heterotypic synonym of true Z. neesanum. Authors of this paper confirmed through extensive field visit in type locality that true Z.neesanum (J.Graham) Ramamoorthy originally described as Alpinia neesana J.Graham from Maharashtra (Khandala & Mahabaleshwar) have cadmium yellow flowers and is endemic to Northern Western Ghats (so far known from only 8 districts of Maharashtra) while widespread and much variable white flowered Zingiber with purplish streaked labellum that was for long treated as Z.neesaum represents other species first named as Z. macrostachyum Dalzell which however is illegitimate name as was not validly published (having no type designated in protologue), thus newly described Z. anamalayanum Sujanapal and Sasidh. forms to be first validly published name for white flowered Zingiber widely distributed in Central and Southern Western Ghats.
As the paper is not freely available so I have added a brief summary and one can go through the abstract on the above given link.