Species of plebejum group comprises seven extant small species of giant water bugs. This group is currently reported from Honduras to southern South America. Two new species are described as a result from a revisional study of this group: Belostoma estevezae Ribeiro & Alecrim, sp. nov., from Mato Grosso State, Brazil, and B. nessimiani Ribeiro & Alecrim, sp. nov., from Amazonas State, Brazil. The prosternal keel of B. estevezae, sp. nov., is similar to that of B. nicaeum Estévez & Polhemus, 2007, while the male genitalia structures of B. nessimiani, sp. nov., is similar to those of B. parvum Estévez & Polhemus, 2007. A key to the species of plebejum group with new species included is also provided.
Nepomorpha; Giant water bugs; Taxonomy; Neotropics; Brazil