gracilis, Gambusia Girard [C. F.] 1859:121 [Proceedings of the Academy of Natural Sciences of Philadelphia v. 11; ref. 27410] Matamoros, Tamaulipas, Atlantic slope of Mexico. Syntypes: ANSP 6973 (1), MCZ 1309 (1), MNHN [ex USNM 3506] (1), ?USNM 3506 (7, not found). Type catalog: Böhlke 1984:143 [ref. 13621], Parenti et al. 1999:7 [ref. 24072]. Subjectively invalid; secondarily preoccupied by Xiphophorus gracilis Heckel 1848, replaced by Gambusia humilis Günther 1866. •Synonym of Gambusia affinis (Baird & Girard 1853) -- (Rosen & Bailey 1963:95 [ref. 7067], La Rivers 1994:532 [ref. 23389], Parenti et al. 1999:7 [ref. 24072], Lucinda in Reis et al. 2003:558 [ref. 27061], Meyer 2015:54 [ref. 34698], Huber 2019:63 [ref. 36941]). 2°Homonym. Current status: Synonym of Gambusia affinis (Baird & Girard 1853). Poeciliidae: Poeciliinae. Habitat: freshwater, brackish.