alexandri, Cynolebias Castello [H. P.] & López [R. B.] 1974:35, Fig. [Tropical Fish Hobbyist v. 23 (no. 1); ref. 17] Parque Unzue, Gualeguaycú, Province de Entre Ríos, Argentina. Holotype: MACN 6438. Paratypes: MACN 2738 (7 or 9), 6425 (7), 6437 (4), 6439 (1). Type catalog: Braga & Piacentino 1994:98 [ref. 23697] as alexandrii. •Valid as Cynolebias alexandri Castello & López 1974 -- (Costa 1995:64 [ref. 22097], Costa 1999:301 [ref. 24229], Costa 1999:93 [ref. 24131]). •Valid as Austrolebias alexandri (Castello & López 1974) -- (Costa 1998:75 [ref. 23792], Lazara 2001:59 [ref. 25711], Costa 2002:917 [ref. 26505], Costa in Reis et al. 2003:527 [ref. 27061], López et al. 2003:69 [ref. 27366], Menni 2004:86 [ref. 28131], Calviño 2005:15 [ref. 28325], Perujo et al. 2005:2 [ref. 28452], Calviño 2006:183 [ref. 28679], Costa 2006:60 [ref. 28708], Costa 2009:188 [ref. 30417], Litz & Koerber 2014:29 [ref. 33622], Mirande & Koerber 2015:50 [ref. 35117], Calviño et al. 2016:8 [ref. 34699], Bertaco et al. 2016:423 [ref. 34561], Nión et al. 2016:42 [ref. 35565], Volcan et al. 2017:150 [ref. 35644], Loureiro et al. 2018:11 [ref. 36240], Loureiro et al. 2023:165 [ref. 40506]). •Valid as Matilebias alexandri (Castello & López 1974) -- (Alonso et al. 2023:9 [ref. 40292], Koerber et al. 2023:11 [ref. 40355], Koerber et al. 2023:4 [ref. 40368]). Current status: Valid as Matilebias alexandri (Castello & López 1974). Rivulidae: Cynolebiinae. Distribution: South America: Uruguay River basin (Argentina, Brazil and Uruguay). Habitat: freshwater.