pygmaeus, Xiphophorus Hubbs [C. L.] & Gordon [M.] 1943:31, Pl. 1 (figs. 1-2) [Copeia 1943 (no. 1); ref. 10860] Río Axtla of Río Panuco system, at Axtla, San Luis Potosí, Mexico. Holotype: UMMZ 124365. Paratypes: UMMZ 108601 (1), 124366 (orig. 173, now 168, 5 c&s); USNM 214158 (29); ZMA [ex UMMZ] 109800 (5). Additional material: UMMZ 196924 [? ex UMMZ 12430] (1). Type catalog: Nijssen et al. 1982:72 [ref. 19236]. •Valid as Xiphophorus pygmaeus Hubbs & Gordon 1943 -- (Rosen & Bailey 1963:65 [ref. 7067], Rosen 1979:356 [ref. 22796], Espinosa Pérez et al. 1993:56 [ref. 22290], Rodriguez 1997:674 [ref. 23266], Morris et al. 2001:69 [ref. 25123], Meyer & Schartl 2002:59 [ref. 26066], Lucinda in Reis et al. 2003:574 [ref. 27061], Nelson et al. 2004:106 [ref. 27807], Lucinda & Reis 2005:44 [ref. 29205], Miller 2006:263 [ref. 28615], Scharpf 2007:24 [ref. 30398], Page et al. 2013:111 [ref. 32708], Meyer 2015:405 [ref. 34698], Huber 2019:151 [ref. 36941]). Current status: Valid as Xiphophorus pygmaeus Hubbs & Gordon 1943. Poeciliidae: Poeciliinae. Distribution: Upper Pánuco River basin, Atlantic slope of Mexico. Habitat: freshwater.