unimaculatus, Metynnis Steindachner [F.] 1908:326 [Anzeiger der Kaiserlichen Akademie der Wissenschaften, Wien, Mathematisch-Naturwissenschaftliche Klasse v. 45 (no. 17) (for 2 July 1908); ref. 18805] Lake at Rio Medonho, tributary of Rio Parnahyba north of Santa Filomena, Brazil [type locality incorrect, Mateussi et al. 2018:303 [ref. 35820], probably the lower Rio Tocantins basin]. Syntypes: (several) NMW 56451 (3). •Questionably a synonym of Mylossoma aureum (Spix & Agassiz 1829) -- (Taphorn 1992:285 [ref. 23654]). •Synonym of Mylossoma duriventre (Cuvier 1818) -- (Zarske & Géry 1999:188 [ref. 23984] as duriventris, Jégu in Reis et al. 2003:187 [ref. 27061], Litz & Koerber 2014:9 [ref. 33622], Mirande & Koerber 2015:15 [ref. 35117], Koerber et al. 2017:22 [ref. 35267]). •Valid as Mylossoma unimaculatum (Steindachner 1908) -- (Mateussi et al. 2018:299 [ref. 35820], Koerber et al. 2022:18 [ref. 39235], Ota et al. 2024:417 [ref. 40817]). Current status: Valid as Mylossoma unimaculatum (Steindachner 1908). Serrasalmidae: Colossomatinae. Distribution: South America: Tocantins-Araguaia system, Amazon basin (Brazil). Habitat: freshwater.