Gall-inducing insects are relatively host-specific compared with their non-galling relatives. In Australia, there have been at least four origins of gall induction among eriococcid scale insects, with the most species-rich genus, Apiomorpha, inducing galls only on species of Eucalyptus. Here we describe two recently discovered species of Apiomorpha that induce galls on eudesmid eucalypts in Western Australia: Apiomorpha gongylocarpae, sp. nov., which is very similar morphologically to A. pomaphora, and A. jucundacrispi, sp. nov., the adult females of which induce an unusual gall covered in woody protrusions that, when older, have a knobbly appearance. Using molecular, morphological and host-association data, we show that these two species form a monophyletic group with the only other species of Apiomorpha that feed on eudesmid eucalypts (A. hilli and A. pomaphora). We place all four species of eudesmid-feeding Apiomorpha in the A. hilli species group, thus revising the current placement of A. pomaphora by removing it from the A. malleeacola species group. This study highlights additional faunal diversity endemic to Western Australia, with two of the four species being restricted to the globally recognised biodiversity hotspot of the South West Australia Floristic Region.