species Megalonaias nervosa (Rafinesque, 1820): synonymy

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 LOST XXX_UNKNOWN, aux rapides de l’Ohio.

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

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

Megalonaias gigantea — Ortmann & Walker (1922), Ortmann (1924), Ortmann (1925), F.C. Baker (1928), Murray & Leonard (1962), ... 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 LOST XXX_UNKNOWN, Fox River of the Wabash.

Quadrula (sec. Crenodonta) heros — Simpson (1900)
Unio (s.s.) multiplicatus — Call (1900)
Quadrula heros — Ortmann (1909)
Crenodonta heros — Ortmann (1912)
Quadrula (sec. Crenodonta) (Group of Q. plicata) heros — Simpson (1914)
Megalonaias heros — Utterback (1915), Ortmann (1923)
Megalonaias gigantea — Ortmann & Walker (1922), F.C. Baker (1928), Murray & Leonard (1962), Morrison (1966), 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)
Unio (s.s.) multiplicatus — Call (1900)
Quadrula heros — Ortmann (1909)
Quadrula (sec. Crenodonta) (Group of Q. plicata) heros — Simpson (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

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

Quadrula (sec. Crenodonta) heros — Simpson (1900)
Quadrula (sec. Crenodonta) (Group of Q. plicata) heros — 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.
TOPOTYPE USNM_83903, Columbus, Georgia.

Quadrula (sec. Crenodonta) boykiniana — Simpson (1900)
Quadrula (sec. Crenodonta) (Group of Q. plicata) boykiniana — 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.
HOLOTYPE (MONOTYPY) USNM_83991 (by R.I. Johnson, 1974: 51), Sabinas R., Nuevo Leon, Mexico.

Quadrula (sec. Crenodonta) heros — Simpson (1900)
Unio (Crenodonta) digitatus — Martens (1900)
Quadrula (sec. Crenodonta) (Group of Q. plicata) heros — Simpson (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 ‘Lea’ of Authors

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

Quadrula (sec. Crenodonta) boykiniana — Simpson (1900)
Quadrula (sec. Crenodonta) (Group of Q. plicata) boykiniana — Simpson (1914)

Unio triumphans B.H. Wright, 1898

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

Quadrula (sec. Crenodonta) triumphans — Simpson (1900)
Quadrula triumphans — Simpson (1900)
Quadrula (sec. Crenodonta) (Group of Q. plicata) triumphans — Simpson (1914)
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

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

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

Plectomerus boykianus Conrad, 1853

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

Unio atrocostatus Reeve, 1864

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

Quadrula (sec. Crenodonta) heros — Simpson (1900)
Quadrula (sec. Crenodonta) (Group of Q. plicata) heros — 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

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

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

Unio eighti Paetel, 1890

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

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