dissimilis, Leucosomus Girard [C. F.] 1856:189 [25] [Proceedings of the Academy of Natural Sciences of Philadelphia v. 8; ref. 1810] Milk River and Little Muddy River, tributary of the upper Missouri River, Montana, U.S.A. Syntypes: UMMZ 56282 [ex USNM 160] (1, lost); USNM 158 (2, plus 1 pair of pharyngeal arches as #2733), 159 (orig. 10, now 0, 1 pair pharyngeal arches as #2734), 160 (orig. 18, now 0). Type catalog: Gilbert 1998:72 [ref. 23395]. On p. 25 of separate. •Synonym of Couesius plumbeus (Agassiz 1850) -- (Lee et al. 1980:150 [ref. 22416], Gilbert 1998:72 [ref. 23395] as an unavailable name for a valid subspecies, McPhail 2007:66 [ref. 31199]). Current status: Synonym of Couesius plumbeus (Agassiz 1850). Leuciscidae: Plagopterinae. Habitat: freshwater.