Unio parallelopipedon Lea, 1834
Lea, 1834, Trans. Amer. Phil. Soc. 5 [O. 1]: 60 [172], pl. 8, fig. 20.
Type(s): HOLOTYPE USNM_85928, Paraná R., Prov. Corrientes, S. America.

Unio parallelopipedon — Lea (1834), Hanley (1843), Hupé (1857), Adams & Adams (1857), Sowerby (1868)
Unio (s.s.) parallepipedon — d’Orbigny (1835)
Margarita (Unio) parallelopipedon — Lea (1836), Lea (1838)
Unio parallelipipedon — d’Orbigny (1846), Corsi (1900)
Margaron (Unio) parallelopipedon — Lea (1852), Lea (1870)
Unio (Diplodon) parallelepipedum — Mörch (1853)
Unio parallelepipedon — Küster (1861)
Diplodon (s.s.) parallelipipedon — Simpson (1900), Simpson (1914), Morretes (1949)
Diplodon (s.s.) parallelopipedon — Ortmann (1921), Figueiras (1965), Bonetto (1965), Rumi et al. (2008), Pereira et al. (2014), Torres et al. (2018)
Diplodon parallelipipedon parallelipipedon — Haas (1930), Parodiz (1968), Mansur (1970), Quintana (1982)
Diplodon parallelipipedon — Haas (1940), Simone (2006)
Schleschiella parallelepipedon parallelepipedon — Modell (1950)
Diplodon parallelopipedon parallelopipedon — Bonetto (1954)
Diplodon parallelopipedon — Bonetto (1959), Schade (1965), Graf & Cummings (2007), Bogan (2010), IUCN (2011), Mansur et al. (2020), Graf & Cummings (2021), Bolotov et al. (2022), Torres et al. (2024)
Diplodon (s.s.) parallellopipedon parallellopipedon — Haas (1969)

Unio acutirostris Lea, 1866
Lea, 1866, Proc. Acad. Nat. Sci. 18: 34.
Lea, 1868, Jour. Acad. Nat. Sci. 6 [O. 12]: 270 [30], pl. 35, fig. 84.
Type(s): HOLOTYPE (MONOTYPY) USNM_85930, S. America.

Unio acutirostris — Lea (1866)
Margaron (Unio) acutirostris — Lea (1870)
Diplodon (s.s.) acutirostris — Simpson (1900), Simpson (1914)
Unio (Sphenonaias) acutirostris — Martens (1900)
Diplodon (s.s.) parallelopipedon — Ortmann (1921), Bonetto (1965), Figueiras (1965)
Diplodon parallelipipedon acutirostris — Haas (1930)
Schleschiella parallelepipedon acutirostris — Modell (1950)
Diplodon parallelipipedon parallelipipedon — Parodiz (1968), Mansur (1970)
Diplodon (s.s.) parallellopipedon acutirostris — Haas (1969)
Diplodon parallelipipedon — Simone (2006)
Diplodon parallelopipedon acutirostris — IUCN (2011)

Unio trifidus Lea, 1860
Lea, 1860, Proc. Acad. Nat. Sci. 12: 89.
Lea, 1863, Jour. Acad. Nat. Sci. 5 [O. 10]: 386 [22], pl. 54, fig. 295.
Type(s): HOLOTYPE USNM_85352, Buenos Ayres, Argentina.

Unio trifidus — Lea (1860)
Margaron (Unio) trifidus — Lea (1870)
Diplodon (s.s.) trifidus — Simpson (1900), Simpson (1914), Ortmann (1921), Morretes (1949), Bonetto (1965), Rumi et al. (2008)
Diplodon parallelipipedon acutirostris — Haas (1930)
Schleschiella parallelepipedon trifida — Modell (1950)
Diplodon trifidus — Bonetto (1954), Parodiz (1968)
Diplodon (s.s.) parallellopipedon acutirostris — Haas (1969)
Diplodon parallelipipedon — Simone (2006)
Diplodon parallelopipedon — IUCN (2011)

Unio digitiformis Sowerby, 1868
Sowerby, 1868, Conch. Icon. 16: pl. 65, sp. 333.
Type(s): HOLOTYPE BMNH_1965199, India.

Unio digitiformis — Sowerby (1868)
Margaron (Unio) osbeckii — Lea (1870)
Nodularia (s.s.) digitiformis — Simpson (1900), Simpson (1914), Preston (1915)
Oxynaia pugio — Haas (1924)
Lanceolaria digitiformis — Haas (1969)
Diplodon parallelopipedon — Bolotov et al. (2022)

Unio parallepipedon d’Orbigny, 1835
‘Lea’ d’Orbigny, 1835, Mag. Zool. 5(61-62): 34.
(error for Unio parallelopipedon Lea, 1834)

Unio parallepipedon — d’Orbigny (1835)
Diplodon (s.s.) parallelopipedon — Figueiras (1965)
Diplodon parallelipipedon parallelipipedon — Mansur (1970)
Diplodon parallelipipedon — Simone (2006)

Diplodon parallelipipedon d’Orbigny, 1846
‘Lea’ of Authors.
d’Orbigny, 1846, Voyage dans l’Amérique Méridionale 5: 609.
Simpson, 1900, Proc. U.S. Nat. Mus. 22: 884.
Corsi, 1900, Anais Mus. Nac. Montevideo 2: 447.
Simpson, 1914, Descr. Cat. Naiades: 1274-1275.
Haas, 1930, Senckenbergiana 12: 189.
Morretes, 1949, Arqu. Mus. Paranaense 7: 18.
Parodiz, 1968, Sterkiana 30: 8.
Mansur, 1970, Iheringia 39: 83.
Quintana, 1982, Rev. Mus. Argentino Zoológicas 11: 128.
Simone, 2006, Land. Freshw. Moll. Brazil.: 260.
(error for Unio parallelopipedon Lea, 1834)

Diplodon parallelipipedon — d’Orbigny (1846)
Diplodon (s.s.) parallelopipedon — Figueiras (1965)
Diplodon parallelipipedon parallelipipedon — Mansur (1970)

Diplodon parallelepipedum Mörch, 1853
‘Lea’ Mörch, 1853, Cat. Conch. Yoldi 2: 47.
(error for Unio parallelopipedon Lea, 1834)

Diplodon parallelepipedum — Mörch (1853)

Unio parallelepipedon Küster, 1861
‘Lea’ of Authors.
Küster, 1861, Conchyl. Cab. 9(2): 220.
Modell, 1950, Arch. Moll. 79(4/6): 141.
(error for Unio parallelopipedon Lea, 1834)

Unio parallelepipedon — Küster (1861)

Unio bonplandii Lea, 1870
‘Valen’ Lea, 1870, Synopsis Fam. Naiades: 63. [nomen nudum]

Unio bonplandii — Lea (1870)
Diplodon (s.s.) parallelipipedon — Simpson (1900), Simpson (1914)
Schleschiella parallelepipedon parallelepipedon — Modell (1950)
Diplodon parallelipipedon — Simone (2006)

Unio paralelepipedus Martens, 1894
Martens, 1894, S.-Ber. Ges. Naturf. Freunde zu Berlin 1894: ??.
(error for Unio parallelopipedon Lea, 1834)

Unio paralelepipedus — Martens (1894)
Diplodon parallelipipedon parallelipipedon — Quintana (1982)

Diplodon fraus Ihering, 1907
Ihering, 1907, Ann. Mus. Nac. Buenos Aires 14: 461, pl. 18, fig. 129.
Type(s): NOMEN NUDUM SMF_3906, Parana, St. Entre Rios, Argentina.

Diplodon fraus — Ihering (1907)
Schleschiella parallelepipedon parallelepipedon — Modell (1950)
Diplodon parallelipipedon — Simone (2006)

Unio acutirrostris Figueiras, 1965
‘Lea’ Figueiras, 1965, Comm. Soc. Malac. Uruguay 1(8): 235.
(error for Unio acutirostris Lea, 1866)

Unio acutirrostris — Figueiras (1965)

Unio bomplandi Parodiz, 1968
‘Valenciennes’ Parodiz, 1968, Sterkiana 30: 3, 12.
(error for Unio bonplandii Lea, 1870)

Unio bomplandi — Parodiz (1968)

Diplodon jickelii Simone, 2006
‘Simpson, 1911’ Simone, 2006, Land. Freshw. Moll. Brazil.: 260.
(misidentified reference to Nodularia (sec. Cafferia) jickeli Simpson, 1900; error for Nodularia (sec. Cafferia) jickeli Simpson, 1900)

Diplodon jickelii — Simone (2006)

Taxonomic History (since 1900)

Diplodon (s.s.) parallelipipedon — Simpson (1900), Simpson (1914), Morretes (1949)
Unio parallelipipedon — Corsi (1900)
Diplodon (s.s.) trifidus — Simpson (1900), Simpson (1914), Ortmann (1921), Morretes (1949), Bonetto (1965), Rumi et al. (2008)
Diplodon (s.s.) acutirostris — Simpson (1900), Simpson (1914)
Unio (Sphenonaias) acutirostris — Martens (1900)
Nodularia (s.s.) digitiformis — Simpson (1900), Simpson (1914), Preston (1915)
Diplodon fraus — Ihering (1907)
Diplodon (s.s.) parallelopipedon — Ortmann (1921), Figueiras (1965), Bonetto (1965), Rumi et al. (2008), Pereira et al. (2014), Torres et al. (2018)
Oxynaia pugio — Haas (1924)
Diplodon parallelipipedon parallelipipedon — Haas (1930), Parodiz (1968), Mansur (1970), Quintana (1982)
Diplodon parallelipipedon acutirostris — Haas (1930)
Diplodon parallelipipedon — Haas (1940), Simone (2006)
Schleschiella parallelepipedon parallelepipedon — Modell (1950)
Schleschiella parallelepipedon trifida — Modell (1950)
Schleschiella parallelepipedon acutirostris — Modell (1950)
Diplodon parallelopipedon parallelopipedon — Bonetto (1954)
Diplodon trifidus — Bonetto (1954), Parodiz (1968)
Diplodon parallelopipedon — Bonetto (1959), Schade (1965), Graf & Cummings (2007), Bogan (2010), IUCN (2011), Mansur et al. (2020), Graf & Cummings (2021), Bolotov et al. (2022), Torres et al. (2024)
Unio acutirrostris — Figueiras (1965)
Unio bomplandi — Parodiz (1968)
Diplodon (s.s.) parallellopipedon parallellopipedon — Haas (1969)
Diplodon (s.s.) parallellopipedon acutirostris — Haas (1969)
Lanceolaria digitiformis — Haas (1969)
Diplodon jickelii — Simone (2006)
Diplodon parallelopipedon acutirostris — IUCN (2011)