Mya variabilis Maton, 1811
Maton, 1811, Trans. Linn. Soc. London 10: 327, pl. 24, figs. 4-7.
(renamed Hyria matoni Gray, 1825)

Mya variabilis — Maton (1811), Dillwyn (1817), Wood (1825)
Hyria corrugata — Lamarck (1819)
Hyria matoni — Gray (1825)
Diplodon rotundus — Wagner (1827)
Margarita (Unio) variabilis — Lea (1836), Lea (1838)
Unio rotundus — Moricand (1838)
Unio variabilis — Hanley (1843), d’Orbigny (1846), Sowerby (1868), Corsi (1900)
Margaron (Unio) variabilis — Lea (1852), Lea (1870)
Unio (Obovaria) variabilis — Adams & Adams (1857)
Diplodon (Cyclomya sec. Bulloideus) variabilis — Simpson (1900), Simpson (1914)
Diplodon (Bulloideus) variabilis — Haas (1931), Thiele (1934), Haas (1969)
Diplodon variabilis — Bonetto (1959), Schade (1965), Parodiz (1968), Graf & Cummings (2021)
Diplodon (Rhipidodonta) variabilis — Parodiz & Bonetto (1963), Figueiras (1965), Bonetto (1965), Pereira et al. (2014), Torres et al. (2018)
Rhipidodonta variabilis — Simone (2006), Graf & Cummings (2007), Bogan (2010), Mansur et al. (2020), Torres et al. (2024)
Diplodon (Rhipidiodonta) variabilis — Rumi et al. (2008)

Unio bulloides Lea, 1859
Lea, 1859, Proc. Acad. Nat. Sci. 11: 187.
Lea, 1860, Jour. Acad. Nat. Sci. 4 [O. 7]: 264 [82], pl. 42, fig. 144.
Type(s): HOLOTYPE USNM_85776, Rio de la Plata, S.A.

Unio bulloides — Lea (1859), Küster (1861), Sowerby (1868)
Margaron (Unio) bulloides — Lea (1870)
Diplodon (Cyclomya sec. Bulloideus) bulloides — Simpson (1900), Simpson (1914)
Diplodon (Bulloideus) variabilis — Haas (1931), Thiele (1934), Haas (1969)
Diplodon bulloides — Bonetto (1959)
Diplodon (Rhipidodonta) variabilis — Bonetto (1965), Figueiras (1965)
Diplodon variabilis — Parodiz (1968)
Diplodon (Bulloideus) bulloides — Haas (1969)
Rhipidodonta variabilis — Simone (2006)

Mytilus membranacea Maton, 1811
Maton, 1811, Trans. Linn. Soc. London 10: 329, pl. 24, figs. 11-12.

Mytilus membranacea — Maton (1811)
Anodon rotundus — Wagner (1827)
Unio (s.s.) matoniana — d’Orbigny (1835)
Margarita (Anodonta) membranacea — Lea (1836)
Margarita (Unio) membranacea — Lea (1838)
Unio membranacea — Hanley (1843)
Anodonta membranacea — d’Orbigny (1846)
Unio membranaceus — Philippi (1848), Küster (1862)
Margaron (Unio) membranaceus — Lea (1852), Lea (1870)
Anodonta membranaceus — Hupé (1857)
Unio (Obovaria) membranaceus — Adams & Adams (1857)
Glabaris (s.s.) membranaceus — Simpson (1900)
Anodonta latomarginata — Corsi (1900)
Anodontites (s.s.) membranaceus — Simpson (1914)
Rhipidodonta variabilis — Simone (2006)

Hyria matoni Gray, 1825
Gray, 1825, Ann. Phil. 9: 138.
(new name for Mya variabilis Maton, 1811)

Hyria matoni — Gray (1825)

Unio matoniana d’Orbigny, 1835
d’Orbigny, 1835, Mag. Zool. 5(61-62): 35.
Type(s): BMNH_1854-9-4-50, Rio de la Plata, Buenos Aires, Argentina.

Unio matoniana — d’Orbigny (1835)
Unio (s.s.) matoniana — d’Orbigny (1835)
Margarita (Unio) membranacea — Lea (1838)
Unio membranacea — Hanley (1843)
Unio variabilis — d’Orbigny (1846), Corsi (1900)
Unio membranaceus — Philippi (1848), Küster (1862)
Margaron (Unio) membranaceus — Lea (1852), Lea (1870)
Unio (Iridea) matoniana — Conrad (1853)
Diplodon (Cyclomya sec. Bulloideus) variabilis — Simpson (1900), Simpson (1914)
Diplodon (Bulloideus) variabilis — Haas (1931), Haas (1969)
Diplodon (Rhipidodonta) variabilis — Bonetto (1965), Figueiras (1965)
Diplodon variabilis — Parodiz (1968)
Rhipidodonta variabilis — Simone (2006)

Unio membranacea Hanley, 1843
Hanley, 1843, Illustr. Descr. Cat. Rec. Bivalve Shells: 202, pl. 22, fig. 6.
(reference to Mytilus membranacea Maton, 1811)

Unio membranacea — Hanley (1843)
Unio variabilis — Sowerby (1868)
Margaron (Unio) membranaceus — Lea (1870)
Glabaris (s.s.) membranaceus — Simpson (1900)
Diplodon (Cyclomya sec. Bulloideus) variabilis — Simpson (1900), Simpson (1914)
Anodontites (s.s.) membranaceus — Simpson (1914)
Diplodon (Bulloideus) variabilis — Haas (1931), Haas (1969)
Diplodon (Rhipidodonta) variabilis — Bonetto (1965), Figueiras (1965)
Diplodon variabilis — Parodiz (1968)
Rhipidodonta variabilis — Simone (2006)

Unio subtrapezius Philippi, 1847
Philippi, 1847, Z. Malak. 4: 96.
Philippi, 1848, Abbild. Beschr. Conch. 3: 80, pl. 5, fig. 3.

Unio subtrapezius — Philippi (1847), Philippi (1848), Küster (1862)
Margaron (Unio) membranaceus — Lea (1852), Lea (1870)
Unio plexus — Conrad (1853)
Glabaris (s.s.) membranaceus — Simpson (1900)
Anodontites (s.s.) membranaceus — Simpson (1914)
Lampsilis (Cyrtonaias) saladoensis — Frierson (1927)
Diplodon variabilis — Parodiz (1968)

Unio locellus Lea, 1866
Lea, 1866, Proc. Acad. Nat. Sci. 18: 34.
Lea, 1868, Jour. Acad. Nat. Sci. 6 [O. 12]: 264, pl. 33, fig. 79.
Type(s): HOLOTYPE USNM_85189, Buenos Ayres, Argentina.

Unio locellus — Lea (1866)
Margaron (Unio) locellus — Lea (1870)
Diplodon (s.s.) locellus — Simpson (1900), Simpson (1914)
Diplodon delodontus wymanii — Haas (1930)
Diplodon (Rhipidodonta) variabilis — Bonetto (1965), Figueiras (1965)
Diplodon burroughianus burroughianus — Parodiz (1968)
Diplodon (s.s.) delodontus wymanii — Haas (1969)
Diplodon burroughianus — Mansur (1970)
Rhipidodonta variabilis — Simone (2006)

Mya variavilis Corsi, 1900
‘Matón’ Corsi, 1900, Anais Mus. Nac. Montevideo 2: 448.
(error for Mya variabilis Maton, 1811)

Mya variavilis — Corsi (1900)

Diplodon subquadratus Marshall, 1922
Marshall, 1922, Proc. U.S. Nat. Mus. 61(2437): 3, pl. 2, figs. 6, 8; pl. 3, figs. 8-10.
Type(s): HOLOTYPE (ORIG. DESIG.) USNM_335774, Paysandu, Uruguay.

Diplodon subquadratus — Marshall (1922)
Diplodon (Cyclomya) paranensis funebralis — Haas (1931)
Diplodon subcuadratus — Bonetto (1959)
Diplodon (Rhipidodonta) variabilis — Bonetto (1965), Figueiras (1965)
Diplodon variabilis — Parodiz (1968)
Diplodon (Rhipidodonta) paranensis funebralis — Haas (1969)
Rhipidodonta variabilis — Simone (2006)

Diplodon subcuadratus Bonetto, 1959
‘Marshall’ Bonetto, 1959, unknown publication: 55.
‘Marshall’ Bonetto, 1965, Anais Congr. Lat.-Amer. Zool. 2: 47.
(error for Diplodon subquadratus Marshall, 1922)

Diplodon subcuadratus — Bonetto (1959)

Taxonomic History (since 1900)

Diplodon (Cyclomya sec. Bulloideus) variabilis — Simpson (1900), Simpson (1914)
Unio variabilis — Corsi (1900)
Glabaris (s.s.) membranaceus — Simpson (1900)
Anodonta latomarginata — Corsi (1900)
Diplodon (Cyclomya sec. Bulloideus) bulloides — Simpson (1900), Simpson (1914)
Diplodon (s.s.) locellus — Simpson (1900), Simpson (1914)
Mya variavilis — Corsi (1900)
Anodontites (s.s.) membranaceus — Simpson (1914)
Diplodon subquadratus — Marshall (1922)
Lampsilis (Cyrtonaias) saladoensis — Frierson (1927)
Diplodon delodontus wymanii — Haas (1930)
Diplodon (Bulloideus) variabilis — Haas (1931), Thiele (1934), Haas (1969)
Diplodon (Cyclomya) paranensis funebralis — Haas (1931)
Diplodon variabilis — Bonetto (1959), Schade (1965), Parodiz (1968), Graf & Cummings (2021)
Diplodon bulloides — Bonetto (1959)
Diplodon subcuadratus — Bonetto (1959)
Diplodon (Rhipidodonta) variabilis — Parodiz & Bonetto (1963), Figueiras (1965), Bonetto (1965), Pereira et al. (2014), Torres et al. (2018)
Diplodon burroughianus burroughianus — Parodiz (1968)
Diplodon (Bulloideus) bulloides — Haas (1969)
Diplodon (s.s.) delodontus wymanii — Haas (1969)
Diplodon (Rhipidodonta) paranensis funebralis — Haas (1969)
Diplodon burroughianus — Mansur (1970)
Rhipidodonta variabilis — Simone (2006), Graf & Cummings (2007), Bogan (2010), Mansur et al. (2020), Torres et al. (2024)
Diplodon (Rhipidiodonta) variabilis — Rumi et al. (2008)