Acaciacapsus, gen. nov. is described as a new plant bug genus, with eight new included species: A. amadeus, sp. nov.; A. appha, sp. nov.; A. aureolus, sp. nov.; A. bournda, sp. nov.; A. emeraldensis, sp. nov.; A. lolworthensis, sp. nov.; A. millstreamensis, sp. nov.; and A. woodwardi, sp. nov. Differential diagnoses and descriptions are given for all species, including salient characters, and the male and female genitalia. An identification key is provided to species. Male genitalia are illustrated, and a habitus photograph is provided for each species. Female genitalia are illustrated for two species. The genus is putatively an Acacia specialist, and has cryptozoic yellowish colouration. The species are primarily found in arid and semi-arid regions of non-monsoonal regions of Australia. The collection events are digitised and their distributions mapped. Aphylogeny of species is given. Modifications are given to male genitalic homologies and are discussed in reference to other Australian orthotylines.