megalostomus, Hysteronotus Eigenmann [C. H.] 1911:171, Pl. 6 (fig. 1) [Annals of the Carnegie Museum v. 8 (no. 1) (art. 3); ref. 1226] Rio das Velhas, Brazil. Holotype: FMNH 54889 [ex CM 3551]. Paratypes: (6, CM) CAS 60471 [ex IU 13171] (4), FMNH 54890 (2). Type catalog: Henn 1928:68 [ref. 12305], Ibarra & Stewart 1987:49 [ref. 12367]. •Valid as Hysteronotus megalostomus Eigenmann 1911 -- (Weitzman & Menezes 1998:186 [ref. 23843], Weitzman in Reis et al. 2003:225 [ref. 27061], Thomaz et al. 2015: Add. 5 [ref. 33893], Menezes et al. 2016:496 [ref. 34593], Quintela et al. 2023:6 [ref. 40727]). Current status: Valid as Hysteronotus megalostomus Eigenmann 1911. Stevardiidae: Stevardiinae. Distribution: South America: upper São Francisco River basin, Minas Gerais and Bahia (Brazil). Habitat: freshwater.