isthmensis, Rivulus Garman [S.] 1895:140 [Memoirs of the Museum of Comparative Zoology v. 19 (pt 1); ref. 1538] Río San José, Costa Rica. Holotype (unique): MCZ 27475. •Valid as Rivulus isthmensis Garman 1895 -- (Bussing 1980:332 [ref. 8732], Villa 1982:143 [ref. 36708], Bussing 1987:123 [ref. 22927], Huber 1992:265 [ref. 20639], Bussing 1998:176 [ref. 24179]). •Valid as Rivulus isthmensis Garman 1895, subspecies isthmensis Garman 1895 -- (Lazara 2001:277 [ref. 25711], Costa in Reis et al. 2003:537 [ref. 27061], Costa 2006:139 [ref. 28875] in subgenus Cynodonichthys). •Valid as Cynodonichthys isthmensis (Garman 1895) -- (Costa 2011:242 [ref. 31655], Angulo et al. 2013:995 [ref. 33194], Angulo et al. 2023:58 [ref. 40676]). Current status: Valid as Cynodonichthys isthmensis (Garman 1895). Rivulidae: Rivulinae. Distribution: Central America: Costa Rica and Nicaragua. Habitat: freshwater.