fuscus, Leiocassis Popta [C. M. L.] 1904:186 [Notes from the Leyden Museum v. 24 (no. 4) (art. 6) (for Oct. 1902); ref. 3547] Upper Mahakam River, Borneo. Holotype (unique): RMNH 7555. Type catalog: Ferraris 2007:103 [ref. 29155]. •Valid as Leiocassis fuscus Popta 1904 -- (Burgess 1989:70 [ref. 12860], Kottelat et al. 1993:63 [ref. 23448]). •Valid as Pseudomystus fuscus (Popta 1904) -- (Mo 1991:140 [ref. 19952], Kottelat & Lim 1996:239 [ref. 23210], Ng & Rachmatika 1999:176 [ref. 23964], Ng & Tan 1999:359 [ref. 24159], Tan & Ng 1999:280 [ref. 24254], Ng & Siebert 2005:6 [ref. 28064], Parenti & Lim 2005:190 [ref. 28285], Ferraris 2007:103 [ref. 29155], Kim & Ng 2008:45 [ref. 29456]). •Valid as Nanobagrus fuscus (Popta 1904) -- (Ng 2008:98 [ref. 29540], Thomson et al. 2008:67 [ref. 29733], Ng 2010:60 [ref. 31047], Kottelat 2013:264 [ref. 32989], Sulaiman et al. 2018:35 [ref. 35802], Ng 2018:40 [ref. 35871]). Current status: Valid as Nanobagrus fuscus (Popta 1904). Bagridae. Distribution: Eastern Borneo to southern central Borneo. Habitat: freshwater.