callistus, Tetragonopterus Boulenger [G. A.] 1900:2 [Bollettino dei Musei di Zoologia ed Anatomia Comparata della R. Università di Torino v. 15 (no. 370); ref. 14722] Carandosiñho near Corumba, Rio Paraguay, Mato Grosso, Brazil. Syntypes: (numerous) BMNH 1900.4.14.63-68 (6), MSNG 37718 (2), MZUT 1365 (1). Type catalog: Tortonese 1940:138 [ref. 21559], Tortonese 1961:182 [ref. 10343]. •Valid as Hyphessobrycon callistus (Boulenger 1900) -- (Fernández & Butí 1996:252 [ref. 22775], Planquette et al. 1996:286 [ref. 22818], Almirón & Casciotta 1999:344 [ref. 24405], Lasso et al. 2001:95 [ref. 25928]). •Synonym of Hyphessobrycon eques (Steindachner 1882) -- (Weitzman & Palmer 1997:224 [ref. 22743], Weitzman & Palmer 1997:141 [ref. 24509], Britski et al. 1999:41 [ref. 24147], Lima & Malabarba in Reis et al. 2003:136 [ref. 27061], López et al. 2003:27 [ref. 27366], Casciotta et al. 2003:102 [ref. 28130], Hein 2009:2 [ref. 30362], Litz & Koerber 2014:15 [ref. 33622], Mirande & Koerber 2015:26 [ref. 35117], Koerber et al. 2017:41 [ref. 35267]). •Synonym of Megalamphodus eques (Steindachner 1882). Current status: Synonym of Megalamphodus eques (Steindachner 1882). Acestrorhamphidae: Megalamphodinae. Habitat: freshwater.