rhodostomus, Hemigrammus Ahl [E.] 1924:405, fig. [Wochenschrift für Aquarien- und Terrarienkunde v. 21 (no. 18); ref. 15433] Rio Tapajoz, near Santarem, Pará, Brazil. Lectotype: ZMB 22626 [apparently not 22616]. Paralectotypes: USNM 273367 [ex ZMB 22626] (2); ?ZMB 20804 (1), 32434 (3). Types mentioned: Paepke 1995:92 [ref. 21847], Zarske & Géry 1995:111, Fig. 7 [ref. 22674] but as 22616. Lectotype selected by Zarske & Géry 1995:112 [ref. 22674]. Type locality described in more detail by Ramsperger 1924:810 [ref. 35915]. The specific name is an adjective. •Valid as Hemigrammus rhodostomus Ahl 1924 -- (Taphorn 1992:224 [ref. 23654], Zarske & Géry 1995:118 [ref. 22674], Lima & Oyakawa in Reis et al. 2003:133 [ref. 27061], Bertaco & Carvalho 2005:147 [ref. 28675], Marinho et al. 2008:59 [ref. 29547], Carvalho et al. 2010:253 [ref. 30862], DoNascimiento et al. 2017:49 [ref. 35633]). •Valid as Petitella rhodostoma (Ahl 1924) -- (Bittencourt et al. 2020:7 [ref. 37634], Lima 2024:249 [ref. 40817]). Current status: Valid as Petitella rhodostoma (Ahl 1924). Acestrorhamphidae: Megalamphodinae. Distribution: South America: Amazon and Orinoco river basins, Brazil, Colombia and Venezuela. Habitat: freshwater.