To date, there are 74 described species of armoured scale insects (Hemiptera: Coccomorpha: Diaspididae) whose only known hosts are bamboos (Poaceae: Bambuseae) and 12 armoured scale insect genera that consist mainly or entirely of bamboo feeders. Fully 71 of the species and all 12 of the genera are native to Asia. Another region where bamboos dominate the forest understory is southern South America, which has high diversity and endemism of bamboos of the genus Chusquea Kunth. We have sampled armoured scale insects from Chusquea from eight different sites in Chile and three sites in Argentina. The most common species were Prodigiaspis riverae (Cockerell) and a morphologically similar undescribed species. We sequenced fragments of four genetic loci from both species: the D2 region of the large ribosomal subunit (28S), elongation factor-1 alpha (EF-1 alpha) and two mitochondria! regions, namely, a fragment of cytochrome oxidase I (COI) and a fragment spanning the parts of cytochrome oxidase I and II (COI-II). We conducted phylogenetic analyses of these sequences, together with previously published sequences of other Neotropical genera of the same tribe (Lepidosaphidini), including an undescribed species of the genus Prodigiaspis Ferris. The results show that the Chusquea-feeding species, including P riverae, comprise a clads that is closely related to the genus Pseudoparlatoria Cockerell and distant from the Prodigiaspis species. Here, we place them in the new genus Chusqueaspis Amouroux gen. nov., with a total of three species, two of which are described here for the first time: Chusqueaspis riverae (Cockerell), comb. nov.; Chusqueaspis patriciae Wei, Claps, Nonnark & Normark, sp. nov.; and Chusqueaspis gonzalezi Amouroux, Normark & Normark, sp. nov. We also describe a Prodigiaspis species as Prodigiaspis megalobus Normark & Normark, sp. nov. on Marila (Calophyllaceae). Illustrations of the adult females of each of the four species and a key to the species of the new genus are provided.