Aim
We aim to reconstruct the phylogeographical history of Musa acuminata subsp. banksii across New Guinea and Australia and to test whether its occurrence in Australia results from ancient natural dispersal or recent human-mediated translocation.

Location
New Guinea and northern Australia (Sahul Shelf).

Taxon
M. acuminata subsp. banksii (F.Muell.) N.W.Simmonds (Musaceae).

Methods
We generated genome-wide single nucleotide polymorphism (SNP) data using DArTseq for samples spanning the subspecies' range. Phylogenomic relationships were inferred using maximum-likelihood locus trees and quartet-based species-tree inference. Divergence times were estimated with time-calibrated analyses in BEAST, and spatial diffusion and lineage dispersal were reconstructed using continuous phylogeographical modelling (SERAPHIM).

Results
Our analyses place the ancestral area of M. acuminata subsp. banksii in the Bird's Head Peninsula approximately 4 million years ago (mya), consistent with the recent emergence of New Guinea. The Central Range of New Guinea likely acted as a major biogeographical barrier and channeled expansion through southern lowland corridors. Australian populations form a deeply divergent lineage that colonised the continent via the Torres Strait land bridge during the early Pleistocene. This colonisation event predates human arrival in the region by more than 2 million years.

Main Conclusions
The presence of M. acuminata subsp. banksii in Australia reflects ancient natural dispersal rather than human translocation. Australian populations represent a vicariant lineage with a distinct evolutionary history, highlighting northern Australia as an overlooked reservoir of wild banana genetic diversity. Our study illustrates how integrating phylogenomics, molecular dating, and spatial diffusion modelling can resolve long-standing biogeographical questions in regions shaped by dynamic geological and climatic processes.