Recent collecting in the remote Pilbara region of Western Australia has revealed substantial increases in the apparent distributions of species of the genus Quistrachia, and the discovery of new forms, raising questions about the morphological taxonomy. To resolve these questions, we examined mtDNA sequences in all known species of Quistrachia, the unidentified new forms and other members of the subfamily Sinumeloninae. Phylogenetic analysis confirmed the monophyly of Quistrachia, including one of the new forms. The two other new forms represent new genera within the Sinumeloninae. Monophyly of each species was confirmed, with the exception of Q. legendrei, in which populations from the Dampier Archipelago and those from the adjacent Burrup Peninsula are in separate clades. Based on phylogeny and levels of divergence within other species in the genus, the Burrup populations appear to be conspecific with Q. turneri. This is supported by anatomical comparisons, but not by shell morphology, which may well reflect the evolutionary plasticity of shell form. Given the patchiness of searches for land snails in the largely inaccessible Pilbara region, additional species almost certainly remain to be discovered. Our study shows the value of including molecular analyses in determining the taxonomic status of new forms.