A Late Ordovician (latest Eastonian) trilobite fauna from mid-shelf deposits in the Gunningbland Formation near Gunningland, central-west New South Wales, includes at least 13 species, among them the illaenid Eastonillaenus goonumblaensis gen. et sp. nov., scutelluid Eokosovopeltis currajongensis sp. nov., lichid Amphilichas shergoldi sp. nov., remopleuridid Remopleurides cf. R. exallos Webby, asaphids Basiliella cf. B fortis (Webby) and Basiliella? sp., encrinurids Cromus cf. C. optimus (Webby, Moors & McLean) and Erratencrinurus (Prophysemataspis) sp., and cheirurids Sphaerexochus sp. and Sphaerocoryphe sp. The new illaenid genus Eastonillaenus groups species from the Upper Ordovician of New South Wales. The trilobites of the Gunningbland Formation are mostly allied to those from other, coeval faunas of the New South Wales island-arc complex, and amplify affinities of eastern Australia to the eastern Gondwanan Eokosovopeltis-Pliomerina Province. Basiliella karmbergensis sp. nov. is described from the shelfal Karmberg Limestone (Middle Ordovician, Yapeenian) in the Florentine Valley, central Tasmania; three Tasmanian species form a group of effaced Basiliella species uniquely lacking genal spines.