nigricauda, Otocinclus Boulenger [G. A.] 1891:234, Pl. 25 (fig. 3) [Proceedings of the Zoological Society of London 1891 (pt 2); ref. 17039] Rio Grande do Sul, Brazil. Syntypes: BMNH 1891.3.16.53-62 (10, now 9). Type catalog: Ferraris 2007:248 [ref. 29155]. •Valid as Otocinclus nigricauda Boulenger 1891 -- (Isbrücker 1980:84 [ref. 2303], Schaefer 1991:6 [ref. 18926]). •Valid as Microlepidogaster nigricauda (Boulenger 1891) -- (Malabarba 1989:150 [ref. 14217], Burgess 1989:439 [ref. 12860]). •Valid as Hisonotus nigricauda (Boulenger 1891) -- (Isbrücker 2001:28, 30 [ref. 25653], Aquino et al. 2001:9 [ref. 25673], Isbrücker 2002:18 [ref. 27178], Britski & Garavello 2003:592 [ref. 27131], Schaefer in Reis et al. 2003:323 [ref. 27061], Almirón & Azpelicueta 2006:93 [ref. 28713], Casciotta et al. 2006:150 [ref. 28758], Britski & Garavello 2007:414 [ref. 29429], Ferraris 2007:248 [ref. 29155], Carvalho et al. 2008:515 [ref. 29799], Chiachio et al. 2008:610 [ref. 30127], Carvalho & Reis 2009:35 [ref. 30193], Koerber 2011:6 [ref. 31122], Garvalho & Reis 2011:3 [ref. 31240], Koerber 2014:9 [ref. 33621], Litz & Koerber 2014:24 [ref. 33622], Roxo et al. 2015:138 [ref. 33763], Mirande & Koerber 2015:41 [ref. 35117], Zawadzki et al. 2016:381 [ref. 34367], Roxo et al. 2016:236 [ref. 34426], Bertaco et al. 2016:418 [ref. 34561], Nión et al. 2016:31 [ref. 35565], Calegari et al. 2017:244 [ref. 35203], Roxo et al. 2018:[12] [ref. 35900], Giora & Wingert 2023:45 [ref. 41026], Loureiro et al. 2023:118 [ref. 40506]). Current status: Valid as Hisonotus nigricauda (Boulenger 1891). Loricariidae: Hypoptopomatinae. Distribution: SouthAmerica: Paraná/Paraguay River basin, Uruguay River basin (Argentina, Brazil and Uruguay). Habitat: freshwater.