Monomorium Mayr is a speciose, cosmopolitan genus of myrmicine ants that has had a challenging systematic history, comprising numerous lineages whose relationships are problematic. This study employed an extensive sampling of mostly Australian taxa, along with exemplars of other genera of Solenopsidini, to examine relationships among the continent’s Monomorium fauna. Sequences from elongation factor 1α F2, wingless and cytochrome oxidase subunit 1 (COI) were analysed using Bayesian and maximum likelihood methods. The resultant phylogeny resolved Australian Monomorium into two major clades separated by exemplars from other genera; one comprised predominantly species with 11-segmented antennae (corresponding to Monomorium s. str. in a recent study of Myrmicinae) along with three Paleotropical species. The second clade included Australian species with 12-segmented antennae, two New Zealand species and two from New Caledonia. Two Australian cryptobiotic species were resolved as sister to Clade 2. COI analysis indicated that some species (M. fieldi Forel, M. leave Mayr and M. leae Forel) possibly represent cryptic species complexes. The New Zealand M. antipodum Forel was recovered as a valid species, and is closely related to an eastern Australian population. We resurrect the genus Chelaner Emery for species in the second clade (with 12-segmented antennae) and outline morphological characters to separate Chelaner from Monomorium s. str. Fifty-three species of Chelaner are treated as either stat. nov. or stat. rev.