Bivalvia | Unionida | Unionoidea | Unionidae | Ambleminae | Lampsilini | Medionidus
2 specimens + 1 GenBank voucher

Lea, 1857. Proc. Acad. Nat. Sci. 9: 171.
Lea, 1859. Jour. Acad. Nat. Sci. 4 [O. 7]: 203 [21], pl. 23, fig. 85.
Type(s): LECTOTYPE USNM_84142, Flint River, near Albany, Georgia.
Medionidus penicillatus — Simpson (1900), Simpson (1914), Frierson (1927), Clench & Turner (1956), Haas (1969), ... Graf & Cummings (2021), FMCS (2021), Hopper et al. (2023), FMCS (2025), Campbell & Lydeard (2026)

B.H. Wright, 1900. Nautilus 13(12): 138.
Type(s): SYNTYPE USNM_159965, Flint R., Baker Co., Ga.
Medionidus kingi — Simpson (1900), Simpson (1914)
Medionidus penicillatus — Frierson (1927), Clench & Turner (1956), Haas (1969), Burch (1975), R.I. Johnson (1977), Brim Box & Williams (2000), Williams et al. (2008), Williams et al. (2011), Williams et al. (2014)
Medionidus penicillatus — Simpson (1900), Simpson (1914), Frierson (1927), Clench & Turner (1956), Haas (1969), ... Graf & Cummings (2021), FMCS (2021), Hopper et al. (2023), FMCS (2025), Campbell & Lydeard (2026)
Medionidus kingi — Simpson (1900), Simpson (1914)