Unio suavidicus Lea, 1856
Lea, 1856. Proc. Acad. Nat. Sci. 8: 95.
Lea, 1857. Jour. Acad. Nat. Sci. 3 [O. 6]: 309 [29], pl. 29, fig. 24.
Type(s): HOLOTYPE USNM_85727, Amazon R., S.A.

Diplodon (s.s.) suavidicus — Simpson (1900), Simpson (1914), Ortmann (1921), Haas (1932), Morretes (1949), Haas (1949), Haas (1969), Pereira et al. (2014)
Diplodon suavidicus — Haas (1930), Bonetto (1959), Figueiras (1965), Mansur & Valer (1992), Ramírez et al. (2003), ... Huang et al. (2019), Guerra et al. (2019), Mansur et al. (2020), Graf & Cummings (2021), Bieler (2021)
Diplodon rhombeus — Parodiz (1968)
Rhipidodonta suavidica — Simone (2006), Graf & Cummings (2007), Bogan (2010)
Diplodon suavidica — ITIS (2013)

Unio demararaensis Lea, 1859
Lea, 1859. Proc. Acad. Nat. Sci. 11: 152.
Lea, 1870. Synopsis Fam. Naiades: 36, Corridenda et Addenda.

Diplodon (s.s.) demararaensis [sic] — Simpson (1900)
Diplodon (s.s.) demeraraensis — Simpson (1914)
Diplodon suavidicus — Haas (1930), Bieler (2021)
Diplodon (s.s.) suavidicus — Haas (1969)

Unio demeraraensis Lea, 1859
Lea, 1859. Proc. Acad. Nat. Sci. 11: 152 [as ‘demararaensis’].
Lea, 1860. Jour. Acad. Nat. Sci. 4 [O. 7]: 253 [71], pl. 39, fig. 133.
Lea, 1870. Synopsis Fam. Naiades: Corridenda et Addenda.
(error for Unio demararaensis Lea, 1859)
Type(s): TYPE BMNH_1964141, Demerara.

Diplodon (s.s.) demararaensis [sic] — Simpson (1900)
Diplodon (s.s.) demeraraensis — Simpson (1914)
Diplodon rhombeus — Parodiz (1968)
Rhipidodonta suavidica — Simone (2006)
Diplodon demeraraensis — Graf et al. (2015), Santos-Neto et al. (2016), Bolotov et al. (2016), Wu et al. (2021)
Diplodon suavidicus — Bieler (2021)

Diplodon hartwrighti Ihering, 1910
Ihering, 1910. Abh. Senckenb. Naturf. Ges. 32: 135, pl. 12, fig. 8a-b.
Type(s): TYPE SMF_3924, Lagoa Alagadinha, St. Goyaz, Bras. Amazonas Geb.

Diplodon hartwrighti — Ihering (1910), Simpson (1914), Bonetto (1959)
Diplodon suavidicus — Haas (1930)
Diplodon (s.s.) hartwrighti — Morretes (1949)
Diplodon rhombeus — Parodiz (1968)
Diplodon (s.s.) suavidicus — Haas (1969)
Rhipidodonta suavidica — Simone (2006)

Diplodon kelseyi F. Baker, 1913
F. Baker, 1913. Proc. Acad. Nat. Sci. 65: 665, pl. 27, figs. 5-7.
Type(s): SYNTYPE ANSP_109371, Rio Jamauchim, Pará, Brazil.

Diplodon kelseyi — F. Baker (1913)
Diplodon suavidicus — Haas (1930)
Diplodon (s.s.) kelseyi — Morretes (1949)
Diplodon beskeanus [sic] — Parodiz (1968)
Diplodon (s.s.) suavidicus — Haas (1969)
Rhipidodonta suavidica — Simone (2006)

Diplodon flucki Morrison, 1943
Morrison, 1943. Nautilus 57: 14, pl. 5, fig. 5-9.
Type(s): HOLOTYPE USNM_521998, above Munduapo, Venezuela.

Diplodon flucki — Parodiz (1968), Graf & Cummings (2007), Lasso et al. (2009), Bogan (2010)
Diplodon (s.s.) flucki — Haas (1969)
Diplodon suavidicus — Graf & Cummings (2021)

Unio demarasensis Paetel, 1890
‘Lea’ Paetel, 1890. Cat. Conch.-Samml. 3: 150.
(error for Unio demeraraensis Lea, 1859)

Diplodon (s.s.) demararaensis [sic] — Simpson (1900)
Diplodon (s.s.) demeraraensis — Simpson (1914)

Unio demerarensis Parodiz, 1968
‘Lea’ Parodiz, 1968. Sterkiana 30: 4.
(error for Unio demeraraensis Lea, 1859)

Rhipidodonta demarcaraensis Simone, 2006
‘Lea’ Simone, 2006. Land. Freshw. Moll. Brazil.: 271.
(error for Unio demeraraensis Lea, 1859)