monticolus, Xiphophorus Kallman [K. D.], Walter [R. B.], Morizot [D. C.] & Kazianis [S.] 2004:11, Figs. 1C-D, 4C [American Museum Novitates No. 3441; ref. 27790] Rio Cahuitepec, upper Rio del Sol, Rio Coatzacoalcos basin, Oaxaca, Mexico. Holotype: UNAL 15256. Paratypes: IBUN-AM 13101 (5), UANL 15257 (1). Plus non-type material. •Valid as Xiphophorus monticolus Kallman, Walter, Morizot & Kazianis 2004 -- (Lucinda & Reis 2005:44 [ref. 29205], Scharpf 2007:17 [ref. 30398], Meyer 2015:397 [ref. 34698], Huber 2019:149 [ref. 36941], Fricke et al. 2024:469 [ref. 41622]). Current status: Valid as Xiphophorus monticolus Kallman, Walter, Morizot & Kazianis 2004. Poeciliidae: Poeciliinae. Distribution: Southern North America: upper Río del Sol basin, Oaxaca (Mexico) endemic. Habitat: freshwater.