Bivalvia | Unionida | Unionoidea | Unionidae | Ambleminae | Quadrulini | Megalonaias

Lea, 1834. Trans. Amer. Phil. Soc. 5 [O. 1]: 28 [140], pl. 1, fig. 1.
Type(s): HOLOTYPE (MONOTYPY) USNM_83898, Canton China? [Central America].
Quadrula (sec. Crenodonta) nickliniana — Simpson (1900), Simpson (1914)
Unio (Crenodonta) nicklinianus — Martens (1900)
Quadrula nickliniana — Pilsbry (1910)
Amblema (Megalonaias) nickliniana — Frierson (1927)
Crenodonta nickliniama [sic] — Haas (1929)
Megalonaias nickliniana nickliniana — Haas (1969)
Megalonaias nickliniana — Contreras-Arquieta (2000), Graf & Cummings (2007), Bogan (2010), Graf & Cummings (2021), Czaja et al. (2023), Cummings et al. (2025), Campbell & Lydeard (2026)
Megalonaias nicklineana [sic] — ITIS (2012)
Megalonaias nervosa — Pfeiffer et al. (2018)

Morelet, 1851. Test. Nov. 2: 24.
Type(s): LECTOTYPE [AS HOLOTYPE] BMNH_93-2-4-2035 (by R.I. Johnson, 1971: 82), flumen Usumacinta, Peten, Guatemala.
Quadrula (sec. Crenodonta) digitata — Simpson (1900), Simpson (1914)
Unio (Crenodonta) digitatus — Martens (1900)
Amblema (Megalonaias) nickliniana-digitata — Frierson (1927)
Crenodonta digitata — Haas (1929)
Amblema digitata — Goodrich & van der Schalie (1937)
Megalonaias nickliniana digitata — Haas (1969)
Megalonaias digitata — Contreras-Arquieta (2000)
Megalonaias nervosa — Pfeiffer et al. (2018)
Megalonaias nickliniana — Cummings et al. (2025)

Martens, 1900. Biol. Centr.-Amer., Moll.: 492, pl. 29, fig. 2.
Type(s): HOLOTYPE (MONOTYPY) ZMB_39464, Rio de las Salinas, Guatemala.
Quadrula (sec. Crenodonta) stolli — Simpson (1900), Simpson (1914)
Unio (Crenodonta) stolli — Martens (1900)
Amblema (Megalonaias) nickliniana-digitata — Frierson (1927)
Crenodonta stolli — Haas (1929)
Megalonaias nickliniana digitata — Haas (1969)
Megalonaias nervosa — Pfeiffer et al. (2018)
Megalonaias nickliniana — Cummings et al. (2025)
‘Lea’ Küster, 1861. Conchyl. Cab. 9(2): 218.
(error for Unio nicklinianus Lea, 1834)
Quadrula (sec. Crenodonta) nickliniana — Simpson (1900), Simpson (1914)
Unio (Crenodonta) stolli — Martens (1900)
Megalonaias nickliniana nickliniana — Haas (1969)
‘Lea’ Haas, 1929. Senckenbergiana 11: 333.
(error for Unio nicklinianus Lea, 1834)
ITIS, 2012. ITIS: [web].
(error for Unio nicklinianus Lea, 1834)
Quadrula (sec. Crenodonta) digitata — Simpson (1900), Simpson (1914)
Quadrula (sec. Crenodonta) nickliniana — Simpson (1900), Simpson (1914)
Quadrula (sec. Crenodonta) stolli — Simpson (1900), Simpson (1914)
Unio (Crenodonta) digitatus — Martens (1900)
Unio (Crenodonta) stolli — Martens (1900)
Unio (Crenodonta) nicklinianus — Martens (1900)
Quadrula nickliniana — Pilsbry (1910)
Amblema (Megalonaias) nickliniana — Frierson (1927)
Amblema (Megalonaias) nickliniana-digitata — Frierson (1927)
Crenodonta stolli — Haas (1929)
Crenodonta digitata — Haas (1929)
Crenodonta nickliniama [sic] — Haas (1929)
Amblema digitata — Goodrich & van der Schalie (1937)
Megalonaias nickliniana nickliniana — Haas (1969)
Megalonaias nickliniana digitata — Haas (1969)
Megalonaias digitata — Contreras-Arquieta (2000)
Megalonaias nickliniana — Contreras-Arquieta (2000), Graf & Cummings (2007), Bogan (2010), Graf & Cummings (2021), Czaja et al. (2023), Cummings et al. (2025), Campbell & Lydeard (2026)
Megalonaias nicklineana [sic] — ITIS (2012)
Megalonaias nervosa — Pfeiffer et al. (2018)