scalaris, Rivulus Costa [W. J. E. M.] 2005:78, Fig. 10 [Neotropical Ichthyology v. 3 (no. 1); ref. 28192] Município de Costa Rica, stream tributary to the upper rio Sucuruí drainage, rio Paraná basin, 18°53'54.7"S, 52°58'44.2"W, Estado de Mato Grosso do Sul, Brazil, elevation 810 meters. Holotype: UFRJ 5968. Paratypes: MCP 36125 (5); UFRJ 2277 (5), 2278 (4, c&s), 5969 (19), 5970 (4). •Valid as Rivulus scalaris Costa 2005 -- (Costa 2006:162 [ref. 28875] in subgenus Melanorivulus, Costa 2008:86 [ref. 29717]). •Valid as Melanorivulus scalaris (Costa 2005) -- (Costa 2011:241 [ref. 31655], Nielsen et al. 2016:87 [ref. 34407], Volcan et al. 2017:92 [ref. 35156], Deprá et al. 2017:121 [ref. 35503], Costa 2018:25 [ref. 35717], Volcan et al. 2018:275 [ref. 35895]). Current status: Valid as Melanorivulus scalaris (Costa 2005). Rivulidae: Rivulinae. Distribution: Paraná River and upper Paraguay river basins, Brazil. Habitat: freshwater.