It is identified that D. viscosa split into two intraspecific groups (group I, II) in the Pleistocene 1.1–2.1 Ma (million years ago) (95% Highest Posterior Density, HPD). These two intraspecific groups are distributed differently within Australia. Group I plants are strandline shrubs growing from north-eastern Queensland to the New South Wales border. This clade has a number of genetically divergent lineages (I:a,b,c,d,e,f,g,). It is identified that subclade Ib shared a last common ancestor with subclade Ia in the mid-Pleistocene, 0.5–1.2 Ma. The Group II plants of D. viscosa is present almost everywhere on the continent. Group II has at least three evolutionary lineages (II a, b and c), which distributions generally overlap. According to West these subspecies have morphological intergradation, particularly in the higher-rainfall regions of Australia, but not in the arid zone, where they generally overlap. There is also a hypothesis of ongoing gene flow between D. procumbens and D. viscosa’s Group II resulting from hybridization events of two populations in central regions of South Australia. The Group II members are believed to disperse in the mid-Pleistocene (0.5–1.2 Ma) from mainland Australia to New Zealand.