Unio (Leptodea) nervosa Rafinesque, 1820
Rafinesque, 1818. Amer. Mon. Mag. 3: 355 [as ‘Potamilus nervosus’]. [nomen nudum]
Rafinesque, 1820. Ann. Gén. Sci. Phys. 5 (13): 296, pl. 80, figs. 8-10 [also as ‘Elliptio nervosa’].
Rafinesque, 1864. [in] Binney & Tryon, reprint: 22, 41.
Type(s): TYPE LOST XXX_UNKNOWN, aux rapides de l’Ohio.

— Simpson (1900), Simpson (1914), Burch (1975)
Truncilla donaciformis — Ortmann & Walker (1922)
Lampsilis (Ligumia) nervosa — Frierson (1927)
Ligumia nervosa — Haas (1969)
Megalonaias nervosa — Morrison (1969), Oesch (1984), Turgeon et al. (1988), Cummings & Mayer (1992), Williams et al. (1993), ... Hauck et al. (2023), Ma et al. (2024), FMCS (2025), Cummings et al. (2025), Campbell & Lydeard (2026)
Megalonaias gigantea — Mathiak (1979), R.I. Johnson (1980)
Tritogonia nervosa — ITIS (2012)
M. nervosa — Marshall et al. (2018)

Unio crassus var. giganteus Barnes, 1823
Barnes, 1823. Amer. J. Sci. 6 (1-2): 119.
(intro'd as intra-sp. of Unio crassus Say, 1817)

— Simpson (1914)
Megalonaias gigantea — Ortmann & Walker (1922), Ortmann (1924), Ortmann (1925), F.C. Baker (1928), Murray & Leonard (1962), Haas (1969), Heard & Guckert (1970), Burch (1975), Gordon et al. (1979), Mathiak (1979), R.I. Johnson (1980), ITIS (2012)
Amblema (Megalonaias) gigantea — Frierson (1927), Haas (1930)
Megalonaias gigantea gigantea — Haas (1969)
Megalonaias nervosa — Morrison (1969), Oesch (1984), Vidrine (1993), Howells et al. (1996), Parmalee & Bogan (1998), R.I. Johnson (1999), Brim Box & Williams (2000), Contreras-Arquieta (2000), Williams et al. (2008), Watters et al. (2009), IUCN (2011), Pfeiffer et al. (2018)
Amblema gigantea — Davis & Fuller (1981)

Unio heros Say, 1829
Say, 1829. New Harm. Dissem. 2(19): 291, sp. 1.
Say, 1858. [in] Binney, Compl. Writings T. Say: 165, 225.
Type(s): TYPE LOST XXX_UNKNOWN, Fox River of the Wabash.

Quadrula (sec. Crenodonta) heros — Simpson (1900), Simpson (1914)
Unio (s.s.) multiplicatus — Call (1900)
Quadrula heros — Ortmann (1909)
Crenodonta heros — Ortmann (1912)
Megalonaias heros — Utterback (1915), Ortmann (1923)
Megalonaias gigantea — Ortmann & Walker (1922), F.C. Baker (1928), Murray & Leonard (1962), Haas (1969), Burch (1975), R.I. Johnson (1980)
Amblema (Megalonaias) gigantea — Frierson (1927), Haas (1930)
Amblema (sec. Megalonaias) heros — Thiele (1934)
Megalonaias gigantea gigantea — Haas (1969)
Megalonaias nervosa — Oesch (1984), Vidrine (1993), Howells et al. (1996), Parmalee & Bogan (1998), Brim Box & Williams (2000), ... Williams et al. (2014), Pfeiffer et al. (2018), Pfeiffer et al. (2019), Graf & Cummings (2021), Cummings et al. (2025)

Unio multiplicatus Lea, 1831
Lea, 1831. Trans. Amer. Phil. Soc. 4 [O. 1]: 70, pl. 4, fig. 2.

Quadrula (sec. Crenodonta) heros — Simpson (1900), Simpson (1914)
Unio (s.s.) multiplicatus — Call (1900)
Quadrula heros — Ortmann (1909)
— de Gregorio (1914)
Megalonaias heros — Utterback (1915)
Megalonaias gigantea — Ortmann & Walker (1922), F.C. Baker (1928), Burch (1975)
Amblema (Megalonaias) gigantea — Frierson (1927)
Megalonaias gigantea gigantea — Haas (1969)
Megalonaias nervosa — Oesch (1984), Howells et al. (1996), Parmalee & Bogan (1998), Brim Box & Williams (2000), Williams et al. (2008), Watters et al. (2009), Pfeiffer et al. (2018)

Unio undulatus Say, 1831
‘Barnes’ Say, 1831. Amer. Conch. 2: pl. 16.
(misidentified reference to Unio undulatus Barnes, 1823)

Quadrula (sec. Crenodonta) heros — Simpson (1900), Simpson (1914)
Megalonaias nervosa — Parmalee & Bogan (1998)

Unio boykinianus Lea, 1840
Lea, 1840. Proc. Amer. Phil. Soc. 1: 288.
Lea, 1842. Trans. Amer. Phil. Soc. 8 [O. 3]: 208 [46], pl. 13, fig. 22.
Type(s): TOPOTYPE USNM_83903, Columbus, Georgia.

Quadrula (sec. Crenodonta) boykiniana — Simpson (1900), Simpson (1914)
Amblema (Megalonaias) gigantea-boykiniana — Frierson (1927)
Crenodonta boykiniana — Clench & Turner (1956)
Megalonaias gigantea boykiniana — Haas (1969)
Megalonaias gigantea — Burch (1975)
Megalonaias boykiniana — Davis (1984), Turgeon et al. (1988), Williams et al. (1993), Rosenberg et al. (1994), Rosenberg et al. (1997), Graf & Cummings (2007), Cummings & Graf (2010), ITIS (2012)
Amblema plicata — Vidrine (1993)
Megalonaias nervosa — Mulvey et al. (1997), Brim Box & Williams (2000), Williams et al. (2008), IUCN (2011), Williams et al. (2011), Williams et al. (2014), Pfeiffer et al. (2018), Graf & Cummings (2021)

Unio eightsii Lea, 1860
Lea, 1860. Proc. Acad. Nat. Sci. 12: 306.
Lea, 1860. Jour. Acad. Nat. Sci. 4 [O. 8]: 367 [49], pl. 64, fig. 192.
Type(s): HOLOTYPE (MONOTYPY) USNM_83991 (by R.I. Johnson, 1974: 51), Sabinas R., Nuevo Leon, Mexico.

Quadrula (sec. Crenodonta) heros — Simpson (1900), Simpson (1914)
Unio (Crenodonta) digitatus — Martens (1900)
— de Gregorio (1914)
Amblema (Megalonaias) gigantea — Frierson (1927)
Megalonaias gigantea gigantea — Haas (1969)
Megalonaias nervosa — Howells et al. (1996), Parmalee & Bogan (1998), R.I. Johnson (1999), Williams et al. (2008), Watters et al. (2009), Pfeiffer et al. (2018), Cummings et al. (2025)

Unio baykinianus Küster, 1861
‘Lea’ of Authors.
Küster, 1861. Conchyl. Cab. 9(2): 181.
Paetel, 1890. Cat. Conch.-Samml. 3: 145.
(error for Unio boykinianus Lea, 1840)

Quadrula (sec. Crenodonta) boykiniana — Simpson (1900), Simpson (1914)

Unio triumphans B.H. Wright, 1898
B.H. Wright, 1898. Nautilus 11(9): 101.
Type(s): HOLOTYPE USNM_150554, Coosa Riv., St. Clair Co., Ala.

Quadrula (sec. Crenodonta) triumphans — Simpson (1900), Simpson (1914)
Quadrula triumphans — Simpson (1900)
Megalonaias triumphans — Ortmann (1923), Haas (1969)
Amblema (Megalonaias) triumphans — Frierson (1927)
Megalonaias nervosa — Parmalee & Bogan (1998), Brim Box & Williams (2000), Williams et al. (2008), Watters et al. (2009), Pfeiffer et al. (2018)

Unio undulata Valenciennes, 1827
Valenciennes, 1827. Receuil Observ. Zool. 2(11-12): 229, pl. 54, figs. 3-3b.
(misidentified reference to Unio undulatus Barnes, 1823)

Quadrula (sec. Crenodonta) undulata — Simpson (1900)
Megalonaias nervosa — Watters et al. (2009)

Plectomerus boykianus Conrad, 1853
‘Lea’ Conrad, 1853. Proc. Acad. Nat. Sci. 6: 260.
(error for Unio boykinianus Lea, 1840)

Unio atrocostatus Reeve, 1864
‘Lea’ Reeve, 1864. Conch. Icon. 16: pl. 4, sp. 13; errata [changed to ‘U. heros, Say’].
(error for Unio heros Say, 1829; misidentified reference to Unio atrocostatus Lea, 1845)

Quadrula (sec. Crenodonta) heros — Simpson (1900), Simpson (1914)
Amblema (Megalonaias) gigantea — Frierson (1927)
Megalonaias gigantea gigantea — Haas (1969)
Megalonaias nervosa — Parmalee & Bogan (1998), Watters et al. (2009)

Unio atrocostatus Sowerby, 1868
‘Lea’ Sowerby, 1868. Conch. Icon. 16: pl. 77, sp. 404.
(misidentified reference to Unio atrocostatus Lea, 1845)

Quadrula (sec. Crenodonta) undulata — Simpson (1900), Simpson (1914)
Amblema (s.s.) plicata-costata — Frierson (1927)

Unio eighti Paetel, 1890
‘Lea’ Paetel, 1890. Cat. Conch.-Samml. 3: 151.
(error for Unio eightsii Lea, 1860)

Quadrula (sec. Crenodonta) heros — Simpson (1900), Simpson (1914)
Megalonaias nervosa — Parmalee & Bogan (1998), Watters et al. (2009)