macrosteus, Corydoras Regan [C. T.] 1912:219 [Annals and Magazine of Natural History (Series 8) v. 10 (no. 56); ref. 14865] Rio Piracicaba, São Paulo, Brazil. Lectotype: BMNH 1905.6.9.12. Paralectotypes: BMNH 1905.6.9.13-15 (3). Type catalog: Ferraris 2007:112 [ref. 29155]. Lectotype selected by Nijssen & Isbrücker 1980:208 [ref. 6910]. •Doubtful species -- (Isbrücker 2001:229 [ref. 26805]). •Synonym of Corydoras aeneus (Gill 1858) -- (Nijssen & Isbrücker 1980:207 [ref. 6910], Reis in Reis et al. 2003:294 [ref. 27061], Ferraris 2007:112 [ref. 29155], Litz & Koerber 2014:23 [ref. 33622], Mirande & Koerber 2015:39 [ref. 35117], Koerber et al. 2017:57 [ref. 35267]). •Possibly valid as Corydoras macrosteus Regan 1912 -- (Tencatt et al. 2023:21 [ref. 40180]). Current status: Uncertain as Corydoras macrosteus Regan 1912. Callichthyidae: Corydoradinae. Distribution: South America: Rio Piracicaba drainage, São Paulo, Brazil. Habitat: freshwater.