orbicularis, Tetragonopterus Valenciennes [A.] in Cuvier & Valenciennes 1850:138 [Histoire naturelle des poissons v. 22; ref. 1014] Essequibo River, Guyana. Lectotype: MNHN 0000-6343. Paralectotypes: MNHN 0000-4400 (1), 1987-1871 (1). Type catalog: Bertin 1948:23 [ref. 19577]. Lectotype selected by Reis 1989:62 [ref. 14219]. •Valid as Poptella orbicularis (Valenciennes 1850) -- (Ortega & Vari 1986:9 [ref. 9708], Taphorn 1992:302 [ref. 23654], Chang & Ortega 1995:7 [ref. 24302]). •Valid as Ephippicharax orbicularis (Valenciennes 1850) -- (Gómez & Chebez 1996:49 [ref. 23791]). •Valid as Brachychalcinus orbicularis (Valenciennes 1850) -- (Reis 1989:60 [ref. 14219], Reis in Reis et al. 2003:209 [ref. 27061], DoNascimiento et al. 2017:46 [ref. 35633], Garcia-Ayala et al. 2017:570 [ref. 35695], Meza-Vargas et al. 2021:17 [ref. 39298], Borstein et al. 2022:16 [ref. 39507], Taphorn et al. 2022:13 [ref. 41297], Garcia-Ayala et al. 2024:9 [ref. 40855]). Current status: Valid as Brachychalcinus orbicularis (Valenciennes 1850). Acestrorhamphidae: Stethaprioninae. Distribution: South America: Amazon and Orinoco river basins (Colombia, Brazil, Guyana, Peru and Suriname). Habitat: freshwater.