Lethocerus maximus De Carlo, 1938: Anls. Mus. Arg. Cien. Nat., 209–210.
Material examined. Laguna Iberá RS: 3 ♂, Fernández Lagoon, 11.xii.2014.
General distribution. The Lesser Antilles, Colombia, Venezuela, Guyana, Suriname, French Guiana, Brazil, Ecuador, Peru, Bolivia, Paraguay, Argentina (Moreira et al. 2011b).
Habitat. Lethocerus maximus has been found in rivers, a reservoir, and it has been taken at lights (Nieser & Alkins-Koo 1991; Perez Goodwyn 2006; Armúa de Reyes & Estévez 2016; Almeida et al. 2019). This species was collected together with L. annulipes in the Paraná River (Argentina), in association with Salvinia sp. and Pontederia crassipes (Armúa de Reyes & Estévez 2016).
At the INR, specimens were collected from the margins of the Fernández Lagoon, exposed to sunlight and with submerged, emergent, and floating vegetation.
Remarks. This is the first record of L. maximus from INR. This species was previously recorded from Corrientes Province (Armúa de Reyes & Estévez 2016).