Genetic relationships among nominal subspecies of the lycaenid butterfly Ogyris amaryllis were investigated in eastern Australia. High levels of variation and population differentiation observed for allozyme markers were not consistent with subspecies boundaries. Partitioning of allozyme variation was explained better by arranging populations according to their larval host plant. Mitochondrial sequence data recovered a polyphyletic inland subspecies, with several peripheral subspecies showing reduced variation within this topology. Non-parametric topology tests rejected monophyly of the nominal subspecies and suggested that allopatric divergence is unlikely to account for the evolution of this complex. Genetic data, combined with information on distribution and ecology, are more consistent with a pattern of peripheral isolation associated with host-plant specialisation of coastal populations.